Archive by Author | marckuchner2014

Our Third Paper: The Advanced Users’ Story

By Katharina Doll, Johanna J.S. Finnemann, Hugo A. Durantini Luca, Joshua Hamilton, and Michiharu Hyogo

As Steven from the science team wrote in his blog post, our third paper has been accepted for publication. Nine citizen scientists from the advanced user team are listed as co-authors.  Today we want to show you the work we did for this paper.

Our contributions for this paper fall into three parts: the image analysis of Robo-AO follow-up images, the classification of M dwarf debris disk candidates presented by Theissen and West (2014), and finding references related to our disk candidates.

1. Analysis of Robo-AO images

As already explained in the glossary and earlier in this blog, only objects with significant Infrared excess in WISE images are pre-selected to be classified.  It is mainly because the circumstellar disks shine brightly in these spectrums. However, there is a major problem: several close-together objects can blend together in infrared, making it look like the sort of infrared excess the disks we are searching for exhibit.. Moreover, there are other astronomical objects which also shine brightly in Infrared spectrum of light such as background stars (located nearby) or much further away, galaxies, interstellar gas and dusts, and AGNs/QSOs outside our own galaxy. The Robo-AO and Dupont telescopes have a better resolution than the flipbooks shown on the classification interface, so we’re able to see contaminating objects that don’t show up when you classify on the main site (and therefore submit something as a “good candidate”).

We learned how to work with software (DS9, which professional astronomers also use) to look at the files from the telescopes and determine any contaminants.  We’ll show you several sample images that we used:

Case 1   Close by Background Objects


Example image of a disk candidate with a close-by background object.

Here is an example image of an object (Zoo ID AWI0000kk6) with a bright object located very close by. It needed follow-up observing because it is already known as a binary system (and had been flagged in the Talk comments).

Case2:    Faint Fuzzy object


Example of a disk candidate with a faint, fuzzy background object.

Another example image (Zoo ID AWI000028h) with a faint fuzzy object located in the corner of the image. This object (located at 11 o’clock from the main target) is likely an extragalactic object like a galaxy or an AGN.

Case 3: Good object in Follow-up Images


Example of a good object with no apparent contamination or confusion.

2. Classification of disk candidates published by Theissen & West (2014)

As Steven explained in his blog post on the paper, members of the advanced user team looked at previously published disk candidates by Theissen & West (2014). Using their WISE IDs, we used the IRSA Finder Chart tool to generate images in the same wavelengths as in the flipbooks on the main site (SDSS, DSS, 2MASS, WISE). Joshua Hamilton added red circles on all images so that we could use the same method on these objects as we do on normal Disk Detective objects.


Theissen & West’s disk candidates found in the IRSA Finder Chart. Red circles displayed were added by a super user, Joshua Hamilton.

We found out that most of the disk candidates from Theissen & West (2014) disk candidates are not present in Disk Detective because they have a low signal-to-noise ratio in WISE 4 (the last image you see in a flipbook), and in addition most are contaminated in our criteria. For example, all were extended in W4 images and thirteen of them consists of multiples.

As you can see in the example above, more than one object is visible in SDSS images, and the bright blue fuzzy objects extend outside the red circle in WISE images . Hence we concluded this object does not satisfy our criteria of our classification process.  

3. Finding references

Lastly, we contributed by finding references related to our disk candidates. About a week before the paper was first submitted, Marc Kuchner, the principal investigator, had asked the super users to look for any interesting references related to the disk candidates of this paper just in case.  We used tools such as SIMBAD and VizieR (which Marc explained here and here on the blog) and searched information regarding each of those candidates.  VizieR provides us with access to a number of astronomical catalogs. Each of these catalogs consists of a major survey mission and it includes astronomical information regarding the object such as distance(parallax), luminosity, and spectral type.   

Let’s show you an example of how it was done.  First we typed in coordinates for each candidate, in this case AWI00062lo, which is shown in one of the figures above.

In the figure, we see the coordinates of the candidate, AWI00062lo.  After we enter this, we are able to see a number of astronomical catalogs related to this object.  

In this figure below, you can see a part of the VizieR site that shows two catalogs inside blue circles.


Example of how catalogs are displayed within VizieR.

Two catalogs shown are Gaia DR2 and FON Astrographic Catalog.  One of these catalogs, Gaia DR2, is especially important because this survey mission measured positions and distances of 1 billion stars with unprecedented precision. The parallax value which determines the distance of a star is provided by Gaia (8.8526 milli-arcseconds =  112.9 parsecs in this case).

Through this simple process, we found a significant catalog in VizieR, Oh et al. (2017), which contains data on some of our candidates including AWI00062lo.  In the Oh et al. (2016) survey, new comoving pairs are searched in the Tycho-Gaia solution. 

This has assisted us to compare our results with Oh et al. (2017): For example, only 1.37% of stars in Oh et al. (2017) are members of comoving pairs while 11% of our candidates are in such pairs.  These results support the hypothesis of Zuckerman (2015) which stated that there is a high frequency of warm debris disks exist within binary systems of young stars.   We also cross-checked with other reference catalogs on VizieR.

4. Who are we?

Finally, a brief look at who we are and what we do in our daily lives.

Joshua – I am from the mid-Michigan area where I work as the Director of Youth Ministry at a large Catholic parish. I have a degree in Media and Information from Michigan State University, which inadvertently came in very handy for this paper. What I love most about Disk Detective is that someone like me, with very little professional training in astronomy, can collaborate on incredible scientific research with people from around the world. Though we are all different, we all share on thing in common: our love of discovery and science. For this paper, I used my design software skills to build a precise overlay for the Theissen and West Paper images that we wanted to study. I took 175 Theissen and West images that they had classified as good disk candidates and overlaid the red circle that you’d normally see when classifying on the Disk Detective website. This allowed us to analyze their images just we do our own and by doing this analysis, we found that many of the “good candidate” disks from their paper were contaminated by multiple objects within the red circles.

Hugo – I am from Cordoba, province of Cordoba, Argentina. Computer technician and a few other things. Aside of citizen scientist now I’m part of the GAF (Grupo de Astrometría y Fotometría / Astrometry and Photometry Group) of Cordoba. My years of experience working with computers were always handy to work with Disk Detective and when we started to work in this paper that was not exception. Several of my experiences with Disk Detective are captured in our blog, but it’s fantastic the range of experience what the projects ended making possible for me. If have the answer the questions about what I do for the project, I think what the best answer is “a bit of everything” since I help with things what can range from website classifications, vetting or literature checking to recording and uploading the hangouts videos, managing the Spanish Disk Detective twitter account and side projects.

The image analysis with DS9 was my first time using that software. The learning curve for the analysis was a bit steep but not difficult. I think that the image analysis with DS9 was the first analysis done for paper 3 or at least one of the first biggest part what we as superusers worked on. I remember how we learned to differentiate between real objects and fake signals in the images, fun process what included sometimes using the rainbow color scheme in DS9 that changes black for fluorescent pink, great for contrast, not so great for the eyes.

I also ended in charge of putting together and organizing the spreadsheets where the superuser group was putting their conclusions in the different batch of objects. If some old notes are correct, in some point also helped downloading and uploading again the batch of objects in smaller chunks to help other users with slower internet connections. Making the notes to learn the difference between ghost and real objects was interesting. Some artifacts were easy to tell apart from real objects, but others not so much. Discussing our findings, doubts and ways to work with DS9 was a great experience overall.

Michiharu – I am from Tokyo, only super user from Japan.  I have lived outside my country for more than two decades.  I have completed masters degree in Astronomy 8 years ago while I was in Australia. I also have completed another masters degree in Information Technology.   I am currently looking for a physics lecturer position in one of the universities in Tokyo. Although the Disk Detective project is not quite related to a research topic I studied while completing masters degree, I have basic knowledge regarding astrophysics and therefore I have been able to learn science behind this project and how to contribute very quickly without major problems.  My main tasks for this project are a normal classifications of DSS, 2MASS, and WISE images, and vetting of those objects classified as good objects in the classification stage, which includes literature reviews, to help further select sample targets for the observations. On top of all these tasks, I worked on image analysis on the ROBO-AO images with several other super users using the DS9 imaging software to look for possible contaminants, for this paper.   

Katharina – I am from the greater Munich, Bavaria region in Germany and currently work as a research assistant in legal history at university. I have degrees in law and business studies. Being a member of the advanced user group is therefore a great opportunity for me to contribute to a completely different field of research! For this paper, I worked on vetting objects classified as good objects and on analysing Robo-AO images for background contaminants using DS9.

Johanna – A cognitive neuroscientist by training, my passion for science has always extended beyond my primary research area. I believe that while boundaries that mark off one field of science from another can of course be useful, they remain artificial constructs and can also get in the way of connecting people and ideas. It’s for that reason that I’ve enjoyed becoming a member of the Disk Detective team; it is an extraordinary opportunity to make meaningful contributions to an area of science without the formal training/qualifications that are so often indispensable. I’ve learned a lot and not just about astronomy but also about serious involvement of the public in science (something my field is still struggling with!) and I hope that I can in turn also use my experience in data science and understanding human cognition and perception to advance the project.

My involvement in this paper (the vetting of the Theissen & West images) was one of the first things I did after joining the advanced user team and it was great to feel involved right from the start – even while I was still finding my feet. Deciding on analysis pipelines to improve the false positives/false negatives is once again a much broader scientific issue and so it was interesting to apply it to our specific problem in identifying the pitfalls of certain classification criteria.

Lily – I am from Singapore. I graduated with a bachelor’s degree in Library and Information Studies. Apart from being a citizen scientist, I am also an amateur photographer. My astronomy journey started in 2003, I have enrolled in a couple of online astronomy courses as well as taking part in several online citizen science projects. When Disk Detective launched in 2014, I quickly registered.  Throughout my time with DD, I have participated in several of its projects; ROBO-AO Imaging of Debris Disks was one of them. My task was to identify possible companion objects and artifacts to a nearby debris disk candidate, and record their locations. I am honored to be part of the team. The knowledge that I have gained from the project is invaluable.

Do you want to join us? If you’ve done 300 classifications and you’d like to get more involved in our next paper, drop us a line at and ask to join the advanced user group.



Gaia and Virtual Reality

Disk Detectives,

This spring we did a big classification push to prepare for the second data release from the Gaia mission, which arrived on April 25, providing distances to more than a billion stars.   This data instantly converted a substantial fraction of our Disk Detective catalog from mystery objects into stars with known distances and spectral types.  Thank you for all your help getting ready for this event!   We’ve been hard at work since then on (at least) two projects involving Gaia Data Release 2 (DR 2) and Disk Detective data.  And here to tell you about one of them is Susan Higashio, a masters student at International Space University who has been spending her summer as an internal at Goddard Space Flight Center, working on Disk Detective data in Goddard’s new Augmented Reality/Virtual Reality lab.




Susan Higashio, at Goddard’s AR/VR lab, exploring Disk Detective discoveries using Virtual Reality. Photo credit: Matt Brandt

Greetings, Disk Detectives!

It’s Susan here and I’m thrilled to be a summer intern with Dr. Marc Kuchner on Disk Detective this summer! When I found out that I would be working at NASA Goddard, I was SUPER stoked; not only because it was NASA, but being from the West Coast of Canada, I was really looking forward to visiting the East Coast of America for the first time! Truth be told, I felt a little (A LOT!) intimidated being in the Astrophysics department here at NASA—especially because my background is NOT Astrophysics—but I quickly learned that one of the great things about citizen science is that with a little hard work and dedication, anyone can be a citizen scientist!


Positions of the Stars with Disks You Discovered: A Screen Shot from Goddard’s VR Lab.

Thanks to all you Disk Detectives for classifying all those stars with debris disks and accretion disks! Now, I’m working on a Virtual Reality (VR) project with these Disk Detective objects. They are loaded into VR with the Gaia DR2 Release, and the Disk Detective objects that you’ve classified light up in the VR system.

In addition to being great fun, VR is a really great way to see stars from different perspectives.  When we evolve their positions backwards and forwards in time, the Disk Detective objects help reveal groups of stars that move together, or “young moving groups”! Stars within a moving group formed from the same event so they are about the same age, originate from the same area in space and move in the same direction at about the same speed. Many of the Disk Detective objects I am looking at are young, relatively speaking, (we’re talking tens of millions of years old, compared to our sun, which is about 4.56 billion years old) and so moving groups can be studied to learn about how our solar system may have formed and evolved over time. There are many known moving groups (e.g., a list of young moving groups can be found here) and stars found in Gaia DR2 that we can see in VR might belong to a known group, or maybe even be part of a new one. Wouldn’t it be exciting if some Disk Detective stars made up a new moving group?


In the 6 weeks that I have been here, I have learned so many new things. I’ve learned how to make calculations to plot H-R diagrams with stellar isochrones, which are helpful to estimate the approximate age of objects, as well as position/proper motion vector diagrams which illustrate the movement of objects over time. These diagrams can be used to plot any interesting Disk Detective objects to see if they move together over time and possibly see if they might form a moving group. I have also been spending time in the VR lab to search for additional stars that move with together with some interesting Disk Detective objects that I have had my eye on. This is not as easy as it sounds!

It’s not all work here though! I’ve had the pleasure of meeting Disk Detective citizen scientists, Josh Hamilton and his wife, Sarah, when they came to visit NASA Goddard. Marc took us all, including Steven Silverberg and another citizen science intern Michaela Allen, on a tour of the integration and test facility. It was really cool that the James Webb Space Telescope had been in the clean room just months earlier and information about the telescope is still on display.


Disk Detective Citizen Scientists Josh and Sarah Hamilton (left) visiting the highbay at NASA Goddard Space Flight Center with Susan Higashio (middle), Steven Silverberg and Backyard Worlds: Planet 9 intern Michaela Allen (right). Photo credit: Marc Kuchner.

I have long dreamed of working at NASA, and because of Disk Detective and citizen science, this has been an unforgettable experience and a dream come true! Many thanks to Marc, without whose support and guidance I would not be here on this internship; to Professor Hugh Hill at ISU, who was formerly at NASA Goddard and who still has many friends here; as well as many other people who I have learned so much from during my stay here so far: Steven Silverberg and the Disk Detective team, Sarah Logsdon, Michaela Allen, and Peter Pokorny; along with the VR team: Matt Brandt, Tom Grubb, and interns Stewart Slocum, Tyler Cahill, and Hayden Hotham, to name a few. I am really looking forward to spending the rest of the summer here and continuing my work with Disk Detective and all of you citizen scientists. Thank you for your hard work and keep on classifying those objects!


My Year In Astronomy, by Citizen Scientist Hugo Durantini Luca

Today we have a guest post from Disk Detective citizen scientist Hugo Durantini Luca., from Cordoba, Argentina, who just returned from another trip to the Complejo Astronómico El Leoncito (CASLEO) observatory to make follow-up observations of our disk candidates.   I think Hugo is going to end up a professional astronomer if he keeps this up!   –Marc 

My Year in Astronomy

First of all, and to avoid repetitions, if you have not read my other post in this blog, you can take a look here:  This post is a continuation of that experience, my love for Astronomy has only get bigger since back them.

2016 and 2017 have been a without a doubt a couple of interesting years for me regarding astronomy, but 2017 takes the prize in my opinion. Even if not in the way that I originally planned or imagined, a lot of the things that I thought back in 2015 started to take form.

While the work in Disk Detective was progressing, 2016 was dedicated to expanding my practical knowledge in Astronomy thanks to the different workshops of the Grupo de Astrometría y Fotometría / Astrometry and Photometry Group (GAF) at the Observatorio Astronómico Córdoba (OAC). I learned some basics about astronomical instruments and more advanced concepts about image processing to be able to make scientifically valuable reports of astrometry and photometry.


Town of Tolar Grande  (Credit: Hugo Durantini Luca)

In 2017 the travel opportunities started to appear again and, of course, I tried to make the most of them, with two travels to CASLEO in the San Juan province for Disk Detective observations, one to the Observatorio Astronómico Tolar (OAT) in the Salta province, and a couple of good experiences in La Estación Astrofísica de Bosque Alegre (EABA) in my own province. Except for CASLEO, the rest were related to my participation in the GAF and IATE.

CASLEO feels after three trips like a very familiar places, so much that even after observing 100 stars this year alone for Disk Detective, I never get tired and always looks forward to return again. Plus, working along Luciano Garcia from the OAC is always a pleasure and a great learning experience. Without a doubt, working with spectrographs never ceases to be interesting.


CASLEO observatory in winter (credit: Hugo Durantini Luca)

This year I enjoyed the opportunity of exploring the landscapes of CASLEO in two different seasons of the year, and along the trip of 2015, now I have almost a complete picture almost complete of how they change throughout the year. What never changes is the enjoyable environment which welcomes our arrival—another reason to return.


CASLEO observatory in springtime (credit: Hugo Durantini Luca)

My trip to Salta and the OAT was the longest distance I have traveled and my longest stay away from home in a very long time, but a wonderful experience for multiple reasons. Not only I never visited before the north of my country, with a visit to the National University of Salta included, I was traveling to collaborate in the project of a new astronomical observatory that is starting to work at the same time that I keep my formation as Telescope Operator and advancing in my Astronomy career with help of exceptional people.

The trip to the OAT, located in the small town of Tolar Grande is, let’s say… a bit longer compared with the trip to CASLEO (1200 vs 750 kilometers), but the landscape alone makes the trip worthwhile. Even with the OAT in a stage of construction, we already were able to capture CCD images with enough quality to make a few first contributions: exoplanet transit reports and others events.  The potential of the site is huge.


Macon mountain range outside Tolar Grande (credit: Hugo Durantini Luca)

Tolar Grande is a town with a bit more than 200 inhabitants, but the calm that possesses you along with an incomparable night sky that surpassed the experience of seeing for the first time the Milky Way at CASLEO. 

Bosque Alegre (EABA) in Cordoba was another great experience this year, was able to interact with both telescopes while we were doing observations for the June transit of transneptunian object MU69. The 1.54 meter telescope is the same one that participated of the kilonova discovery that traveled the world with the news of the first gravitational wave event with a confirmed optical counterpart (is worth to mention that the OAT also tried to contributed there), but in this case I worked with the Perrine Telescope (76 cm).

I could keep writing pages upon pages describing in detail all the experiences, but that is not the idea of this post. The idea was to present a small summary of my experiences and current activities, whose initial seeds started in Disk Detective and then started to branch off in ways that I was unable to imagine. Citizen science is without a doubt an invaluable tool for common people to get involved with subjects what they love, maybe at first only like a hobby, maybe later like the start of a career in the scientific world.

Never stop chasing your dreams, and in the case of Astronomy, looking to the skies!

With thanks to Marc Kuchner, Steven Silverberg, Alissa Bans and Milton Bosch from Disk Detective, to the people of the Space Telescope Science Institute–Bernie Shiao, John Debes and Geoff Wallace–and the people of the OAC / GAF / IATE–Diego García Lambas, Carlos Colazo, Matías Schneiter, Cecilia Quiñones, Rodolfo Artola, Carla Girardini, Raul Melia and others. Without them I would not be writing these words, with so many projects in my mind that I hope to get done.



Dome to be installed in the Astronomical Observatory of Tolar / Observatorio Astrómico Tolar (OAT)  credit: Hugo Durantini Luca

Odds and Ends

Howdy Disk Detectives,

Just thought I’d give you an update on some goings on since our last blog post.

First of all—the project is now 59% complete!  That’s fantastic.  Keep up the good work, everybody!   The James Webb Space Telescope is set to launch next fall, and start taking science data in the spring of 2019.  Let’s try to finish up all the classification work by then!  I bet we can.


Disk Detective Milton Bosch visits NASA Headquarters.

Second of all, Goddard Space Flight Center held a “Citizen Science/Crowdsourcing Week” this summer, and Disk Detective’s own Dr. Milton Bosch came out to participate.  Milton also spent a day visiting NASA headquarters, talking to scientists and managers about how citizen science can help NASA.  The goal of the week was to encourage more scientists at Goddard and the rest of NASA to launch citizen projects and use crowdsourcing in their research. It was a huge success! There were nine talks on citizen science and crowdsourcing, and Milton met with 16 different scientists from all our scientific divisions at Goddard. We are planning to do it again next year; let us know if you might want to come down to Greenbelt, MD and participate!

Third of all, I can report that our ALMA proposal did not get selected.  But it was a near miss–and we are going to try again!  We submitted a proposal called “Sub-millimeter Observations of Long-lived Accretion Disks'”asking to measure submillimeter radiation from dust around WISE J080822.18-644357.3, the record-breaking disk we discovered plus a few other similar object. The review panel ranked the proposal in the second quartile and gave us a few tips on how to improve it for next round.

In other news, a handy new catalog of disks has appeared online: This catalog shows what we dream of at Disk Detective: disks that have been “resolved” by telescopes.  “Resolved” means that an image of the disk shows more than a dot of light; it actually has the shape of a disk, maybe even a disk with some structure.  Anyway, if you want to see some of the awesome images that keep us disk researchers motivated, take a peek at

Behind the scenes, the science team is busy working on papers about our follow-up observations from the FAST spectrograph, Robo AO, and the duPont telescope.  The advanced users group is vetting objects of interest for future proposals and looking for new moving groups.  And we’re finding lots of interesting disks!

Stay tuned for more news—and keep up the good searching!

Marc Kuchner






We won an award!

Good news, everyone: the Disk Detective team won an award from NASA!

Disk Detective received a 2016 Robert H. Goddard Honor Award for Exceptional Achievement in Outreach by a team.


We won this award for “providing an outstanding example of how NASA can serve the public by including them in the process of astronomical discovery.” If that’s not a perfect description of Disk Detective, I don’t know what is.

Marc accepted the award on behalf of the team. However, he wasn’t the only one there; also in attendance were Steven Silverberg (i.e., me, from the science team), and Katie Lowe, a member of the advanced user group who lives in Baltimore and came down to Goddard Space Flight Center for the day.


It’s thanks to the contributions of everyone–especially our citizen scientists–that we were able to win this award. Thanks to all of you for your contributions to the project, and keep up the good work!  (The project is about 55% complete.)

Steven Silverberg


Another Expedition to Chile!

Steven Silverberg from our science team recently traveled to Chile again, as he did in October 2015. Here’s his story on our most recent observing run.

Last December, Disk Detective applied for and was granted time at Cerro Tololo Inter-American Observatory, the Southern Hemisphere counterpart to Kitt Peak National Observatory in Arizona. I traveled to Chile last month to conduct the observations.

Due to an issue with flights, I unfortunately missed our planned first night on the telescope. However, I was able to get up to the mountain for nine nights of observations with the 0.9-m telescope, as well as half a night with the 4m Victor Blanco Telescope.

vlu7pehThere are quite a few telescopes on the mountain. In addition to the 5 telescopes that belong to CTIO (the 4m Victor Blanco, and the 1.5m, 1.3m, 1.0m, and 0.9m telescopes run by the SMARTS consortium), there are a slew of other projects hosted on the mountain. The collection of domes makes for a rather impressive site–especially when viewed from the lodge at dawn.

ye75siuSunrises were a thing of absolute beauty coming over the mountains, from anywhere in the complex. This was from the lodge.

yunhg8iMy first nine nights on the mountain were spent with this telescope, the 0.9-m. While not the biggest telescope, it proved quite capable for our mission: monitoring AWI0005x3s (from Paper 2) for flares and other stellar activity. The activity we detect in these observed light curves could give us more information as to its age, and could provide information on how the star and its disk might interact.

gg21nneThe next mountain over (or what seems like it) is Cerro Pachon, home to the SOAR telescope, another telescope run by CTIO. This mountain is also where the Large Synodic Space Telescope (LSST) is currently under construction. Seeing our “neighbors” from the summit of Cerro Tololo was quite nice.

night_4_completeThe most notable result from our initial analysis is the light curve from night 4, where we observed this flare. It is rather impressive, both for its duration (~1.8 hours) and its brightness (3 times the non-flare brightness at peak). This flare, any others we find in the light curve, and any other interesting features we find in the light curve will be the subject of a future Disk Detective paper.

tstoennSunrise on the morning of night 5 was particularly beautiful from on top of the mountain.

The view from the dining hall at the lodge was rather spectacular, as well. You can see what appears to be an ancient riverbed in the valley.

Sunsets could be particularly delightful, too. This one’s beauty comes from some rather annoying clouds, but these fortunately never came into play for our target of interest. We had fairly good observing weather throughout the run.

nikeke3In addition to our time with the 0.9m telescope, we also had time on the 4.1m Victor Blanco Telescope, using the COSMOS instrument. We used this spectrograph to get what we believe is the first optical spectrum recorded of AWI0005x3s. That would give us more accurate information on its spectral type (and temperature), age (to confirm membership in Carina), and potentially radial velocity (also to confirm Carina membership).

All in all, traveling to CTIO was a fantastic experience. I gained some valuable practical experience for future observing runs, and we got what should be some quite good science out of the observations. Keep checking back here, and you should see more on what we learned from our observations soon.

Our Second Paper and a New Kind of M Dwarf Disk

Our second paper just got published! Steven Silverberg, the lead author on the paper, tells up more:

More kudos to us! Our second paper was published by The Astrophysical Journal Letters over the weekend. It will be going up on astro-ph later today. In it, we discuss a potential new kind of disk we’ve found, around an M dwarf.

M dwarfs are really valuable targets to look for. They’re smaller and less massive than the Sun, which makes it easy to find planets around them with the most common detection methods used, radial velocity and transit searches. There are more of these stars in the solar neighborhood than any other kind of star, too. Our nearest neighbor star, Proxima Centauri, is an M dwarf; you may recognize the name from the recent discovery that it has a planet orbiting it <with link to story on it from somewhere>. Since we expect disks to appear about as often as planets appear, we would expect to see lots of M dwarf disks, too, but we haven’t observed that many. The largest survey of M dwarf debris disks to date only found ~175 new disks, and most of those were quite old, over 1 billion years old. Young disks are in some ways more interesting, since any planets around the star would be young enough and therefore warm enough to observe via direct imaging (like the planets around Beta Pictoris).

One method we have of determining the age of a star is seeing if it is a member of a Young Moving Group (YMG). These are groups of stars whose position and motions through the galaxy, along with age indicators in their spectra, suggest that they were born in about the same place at about the same time. Using the online tool BANYAN II by Jonathan Gagne, we can test the likelihood that a star is a member of a moving group, based solely on its observable astrometics (its coordinates, its parallax, its proper motion, and its velocity directly toward or away from us). And you all have found…


…the oldest M dwarf in a YMG! You first met this object at AWI0005x3s, and flagged it as good. We ran its astrometry data through BANYAN II, and found that it has a 93.9% chance of being a member of the ~45 Myr-old Carina association. Very cool, right?

Well, that’s not all. Because it’s a very unusual disk, too.

As stars form, their circumstellar material is mostly gas and dust that settles into a YSO disk. As time goes on, the gas usually accretes onto the star, forms gas giants, or is blown out of the system, leaving the dust behind as a debris disk. Since there’s more material, the gas disk is usually hotter and more massive than the dusty debris disk. This usually occurs in the first 20 Myr or so of the system’s existence.

This star, however, shows a large infrared excess in both the W3 and W4 bands, which suggests that it’s warm (~263 K) and massive. That implies that there’s still a lot of gas in the system, but there’s not enough data yet to tell us *why* that is. It could be an unusually old YSO disk, or it could be something we’ve never seen before.


To help us get a sense of what the system might look like from an artist’s perspective, we enlisted the help of one of our Disk Detectives, Jonathan Holden. Jonathan put together this rather stunning depiction of what this system might look like, that we’ll be using in press releases about this discovery.

You’ll also notice that there are eight citizen scientists listed as co-authors on the paper: Joseph R. Biggs, Milton Bosch, Katharina Doll, Hugo A. Durantini-Luca, Alexandru Enachioaie, Phillip Griffith, Sr., Michiharu Hyogo, and Fernanda Piniero. These fellow Disk Detectives on the Advanced User team helped collect the kinematic data from online astronomical catalogs that we used to test each object with BANYAN II. If you’ve done more than 300 classifications and you would like to join the group, email us at

Great work, everyone! Two papers accepted in the space of four months is excellent progress for the project, and there’s more on the way. Stay tuned, and keep classifying!

Our First Paper and the First Debris Disk with a White Dwarf Companion!

Congratulations, us!  Our first paper was accepted for publication in the Astrophysical Journal. The journal will copy-edit it and typeset it nicely.  But in the meantime, you can read a draft online here at the astro-ph archive. If you spot any errors, please let us know. The paper describes how the project works (you’re probably familiar with that) and announces 37 new disk candidates, including what looks like…

HD74389.diagram the first debris disk around a star with a companion white dwarf!  You met this star, HD 74389,  as subject AWI00000wz and several of you (including Artman40 and  Dolorous_Edd) immediately recognized it as a good candidate, roughly two years ago.  Well, amazingly, this critter is the first of its kind.  Stars with white dwarf companions are common; some of the brightest stars in the sky have white dwarf companions, like Sirius and Procyon.  And this star is an “early A” type star, meaning its about twice as hot as the Sun. Debris disks around “A” stars are fairly common; maybe 15-20% of A stars host debris disks.  But for some reason, nobody had ever found a star with BOTH a debris disk and a white dwarf companion.

One possible reason for why these objects are rare is that the birth of a white dwarf is somewhat violent.  In astronomy, we generally assume that the all the stars in a binary or triple system formed at the same time. More massive stars live shorter lives; they turn into white dwarfs (or neutron stars or black holes) sooner.  So that means the white dwarf in this system probably came from a star slightly more massive than the A star that has the debris disk, maybe a B type star.  This B star lost most of its mass–more than the mass of the sun–into a wind that shines for a while as a planetary nebula. This wind can blow away the small dust grains that are the part of debris disks that we actually see with our telescopes.


Sirius, the brightest star in the sky, is an A star with a white dwarf companion.  Add to this picture another companion star AND a debris disk and you’ve got HD 74389. (HST/Kuchner & Brown 1999)

However, there are three stars known that have extrasolar planets orbiting them that have white dwarf companions.  So maybe this wind isn’t all that harsh on planetary systems.   Alternatively, some theorists have suggested that the wind from an evolved star can form a new disk around the star’s companion. So maybe this disk we saw is a kind of second-generation debris disk.

To make things even weirder, HD 74389 also has an M dwarf companion; it’s what’s sometimes called a hierarchical triple, meaning that the M dwarf and the A dwarf look like a somewhat close binary, and the white dwarf orbits much farther out.  The distance to this triple system is about 111 parsecs (360 light years), based on observations from the Hipparcos telescope.  Based on that distance and the separation between the images of the A star, the M dwarf and the white dwarf, we can estimate that the white dwarf orbits roughly 2200 astronomical units (AU) away from the A star with the disk.  The M star orbits much closer in, at about 400 AU.   For comparison, Pluto’s orbit around the Sun is about 39 AU.

Besides this exotic object HD 74389, our paper reports thirty two other new debris disk candidates that we found and it describes a new detection of 22 micron excess from a previously known debris disk host: the star HD 22128. About half of the new debris disks are close enough to the Sun that they are potential targets for imaging with coronagraphs to search for extrasolar planets that could be lurking within them.

The paper reports four more interesting objects that we discovered, classical Be stars HD 6612, HD 7406, HD 164137, and HD 218546.  A classical Be star is a funny kind of beast: a rapidly rotating star surrounded by a disk made of gas. Nobody knows quite how these objects form, but it seems most likely that the gas disks are ejected from the stars themselves.  These objects are not the kind of disks that are thought to host planetary systems, but they are fun to think about nonetheless. Here’s a handy review paper about Be stars you might like.

The paper lists the user names of everyone who helped classify one of the new disks–and you may have noticed the eight of the authors of this paper are citizen scientists: Joseph Biggs, Milton Bosch, Tadeas Cernohous, Hugo A. Durantini Luca, Michiharu Hyogo, Lily Lau Wan Wah, Art Piipuu, Fernanda Pineiro.  They are members of the Disk Detective Advanced Users Group who helped do some of the more in depth background research on the stars discussed in the paper. If you’ve done more than 300 classifications and you’d like to join this group, just send an email to

Nice work, everybody!  And we’re just getting started.  Stay tuned for more papers later this year.

My travel to CASLEO (The El Leoncito Astronomical Complex).

When you find a good candidate at Disk Detective, it goes into our queue to be researched and often to be re-observed.  Many of those good candidates that are in the Southern Hemisphere get re-observed from the CASLEO observatory in Argentina, where we split up their light with a spectrograph to find out what kinds of stars they are. 

Disk Detective Hugo Durantini Luca lives in the city of Cordoba, Argentina, much closer to the CASLEO observatory than most of us on the Disk Detective science team, but still a long journey away from it.  He traveled for more than eighteen hours across the country of Argentina to join a Disk Deective observing run. Hugo spent five days on the mountain with Luciano García (astronomer from Observatorio Astronomico de Cordoba) helping observe good candidates.  He wrote down some memories from the trip to share with us.  I think you’ll find them as inspiring and poetic as I did!

You can read about his experiences below, and even watch some short videos he took at the observatory:
Dentro de la Cúpula de CASLEO / Inside the CASLEO Dome
Afuera del Observatorio de CASLEO / Outside the CASLEO Observatory
Centro de Control de CASLEO / CASLEO Control Room

My Travel to CASLEO

by Hugo Durantini Luca

Reaching CASLEO requires a little patience. Even if you were to reach the city of San Juan by plane, you still have to endure traveling approximately 5 and half hours more to reach the observatory. The landscape is very interesting, especially if it’s your first time in the region, with the mountains presenting multiple colors and the sight of the Andes while you gradually approach to its foot.

Hugo at CASLEO

Disk Detective Hugo Durantini Luca in front of the Jorge Sahade Telescope dome at CASLEO.

After getting off the bus to San Juan, I was greeted almost immediately by Luciano García and we started our travel to the observatory after picking up some staff that also was going to the complex to start their work shifts. I don’t know if was because I just had made a 8 and a half hour trip, or if it was because of the landscape and the excitement, but the travel of almost 5 hours from the city to the complex felt pretty quick and we reached the place just in time for lunch.

After that, we checked in to our rooms and I was able to do a small tour to see with my own eyes the telescope along with the instrument what we were about to use: the REOSC Spectrograph. The sensation of seeing all the instruments and the control room in person was almost like going back to my childhood, even though I had previously checked all available information on the internet.

I must say that the first night was a bit hard, not only because at first we lost the first hour or so thanks to the clouds, but also because after we started the work and learned the basics of what we were about to do, fighting the urge to sleep and our biologic clocks was something that required a little technique.

To input the coordinates of the star that we wanted to observe and then to give the order to REOSC to initiate the exposure was a great privilege.  I was assigned this task for the whole run.  But even repeating this process over and over didn’t diminish the excitement of directly generating new data for our research.

Another amazing experience was to go outside of the telescope and be able to contemplate the Milky Way in a clean and clear sky.  I saw details that are impossible to see from the city due to light pollution, treasures that the people that have never left the city or studied astronomy don’t know they are losing.

Hugo_Casleo_yellowsignIt was really fun and illuminating for me to participate in all the nights, to watch how the instrument behaved according to the magnitude of the stars.  I learned how to add more or less time to obtain a good reading and how in some cases, there is no trick aside from perseverance. All this experience brought me closer to a better understanding of the work of an astronomer beyond all the commons fantasies that one can hold.

The second day was much easier than the first, at least in the sleep management department. Even if your body is still complaining about some things; one can feel how it adapts to the day to night change. The second night was when we ended doing most of our brightest stars because even if they can be a little difficult, there is less exposure time required.  I also had the chance, thanks Luciano, to explore and visit a few sites close to the complex. The landscape and autumn colors, views almost like paintings, and the lonely roads added to the unforgettableness of the trip.

All the CASLEO staff that we had the opportunity to interact with were extremely kind and it was like being at home almost all the time. Even though we were just there four days, by the end, I felt like I had been there for a long time.  The return trip was somewhat bittersweet. You miss home, but at the same time this experience has reinforced to the max my love for science and especially astronomy.

To pass days far away and entire nights collecting information can look like something disconnected from reality, but it’s actually the opposite. To gain consciousness of the scale of our Galaxy and our place in the universe is an experience that makes you humble, and being able to participate in building our knowledge and understanding of the universe fills me with a sense of obligation to others here in our own world.



Disk Detective FAQ auf Deutsch

Disk Detective Häufig gestellte Fragen

Wir sind stolz, euch heute die Antworten auf eure häufig gestellten Fragen zu Disk Detective (Frequently Asked Questions, FAQ) vorzustellen. Besonderer Dank gebührt Glenn, Katharina, Lily, Fer, Phillip, Maxim, Hugo, Doug, Michi, Ted und dem Rest der Gruppe der fortgeschrittenen Benutzer (Advanced User Group) für die Hilfe bei der Zusammenstellung (und für diese Übersetzung Katharina!). Here is the FAQ in English. Aquí está el FAQ en español.

“Die Frage ist nicht ob, sondern wie. Das Spiel hat begonnen.” – Sherlock Holmes

1. Wie entscheidet man, ob ein Objekt ein guter Kandidat ist?

Ein Objekt ist ein guter Kandidat, wenn es in den DSS-/Sloan- und 2MASS-Bildern rund erscheint, keine Anzeichen für mehrere Objekte im roten Kreis zeigt, im Fadenkreuz bleibt und nicht in den WISE-Bildern aus dem Kreis herausragt. Natürlich wusstest Du das schon durch das Lesen der Buttons – aber hier gibt es (unten) einige weitere Details dazu, was diese Buttons bedeuten.

2. Was ist die Grenze für “rund”?

Ein guter Kandidat macht einen runden Eindruck, während man die Bilder durchsieht, aber die Form kann in einigen Einzelbildern verzerrt aussehen. Wenn er hell ist, könnte er “sternenähnlich” aussehen und in den Bildern bei kurzer Wellenlänge von vier Spitzen umgeben sein. Sehen wir uns einige Beispiele an.

Hier ist ein Beispiel eines guten Kandidaten, bei dem die Form verzerrt wirkt. Entscheidend ist, dass die Form in unterschiedlichen Wellenlängen auf unterschiedliche Arten verzerrt ist. Das DSS2-Bild ist zum Beispiel verzerrt, sogar verpixelt. Aber im Feld sind auch andere Sterne und man kann sehen, dass sie alle ein wenig auf dieselbe Art verzerrt aussehen. Das sagt Dir, dass es ein kleines Problem mit der Optik gab, als das Bild aufgenommen wurde; nicht das Objekt selbst hat eine verzerrte Form.

Bright Star screenshot

Dieser helle Stern ist ein guter Kandidat, auch wenn das DSS2-Blue-Bild (oben) vier Beugungsspitzen zeigt.

Das hier ist ein sehr heller Stern, der ein guter Kandidat ist. Die meisten Objekte, die Du in Disk Detective sehen wirst, sind viel lichtschwächer als dieser! Bei kürzeren Wellenlängen (DSS Blue, Red und Infrarot) erscheint der Stern als große Scheibe mit einem Kreuz aus vier Spitzen. Diese Spitzen sind Sternenlicht, das an der Abstützung des Sekundärspiegels gebeugt wurde. Sie haben nichts damit zu tun, wie der Stern tatsächlich aussieht.

Hier ist ein weiterer guter Kandidat. Du wirst bemerken, dass die Form in einigen Wellenlängen verzerrt wirkt. Das DSS-IR-Bild sieht zum Beispiel ein wenig quadratisch aus – das passiert mit den Beugungsspitzen bei etwas lichtschwächeren Objekten; sie erscheinen nicht als Kreuz, sondern nur als Verzerrung des Bildes. Das 2MASS-K-Bild wirkt länglich. Im WISE-1-Bild wölbt sich das Objekt nach links unten. Aber alle diese Verzerrungen sind in unterschiedlichen Wellenlängen verschieden – also zählt keine davon! Du kannst nur davon ausgehen, dass Du ein echtes astronomisches Phänomen beobachtest (im Unterschied zu einem Problem mit dem Teleskop), wenn Du es in zwei Wellenlängen siehst.

Sehen wir uns als Kontrast dazu dieses Objekt an, das KEIN guter Kandidat ist. Die Form ist von links nach rechts gestreckt und obwohl die Form sich ein wenig von Bild zu Bild verändert, kannst Du erkennen, dass sie in die gleiche Richtung länglich bleibt (außer in einigen Wellenlängen).

3.Wann sagt man, dass “mehrere Objekte im roten Kreis” sind?

Sehen wir uns einige Beispiele an. Ich zähle mindestens drei Hintergrundobjekte innerhalb des roten Kreises bei diesem Studienobjekt (neben dem Objekt in der Mitte). Diese anderen Objekte könnten das SED des Objekts kontaminieren, für das wir uns wirklich interessieren, nämlich das in der Mitte des Kreises.

Bei diesem Studienobjekt ist ein Objekt am Rand des roten Kreises und streut Licht in den roten Kreis hinein. Das zählt! Du müsstest hier auf “Mehrere Objekte im roten Kreis” klicken.

Denk einfach daran, dass ein Hintergrundobjekt nur zählt, wenn Du es in zwei Wellenlängen sehen kannst. Hier ist ein Beispiel. Das DSS2-Bild dieses Studienobjekts zeigt eindeutig einige Hintergrundobjekte im Inneren des roten Kreises. Ich sehe Hintergrundobjekte bei ein Uhr, vier Uhr, sieben Uhr und 10 Uhr (wenn der rote Kreis ein Zifferblatt wäre). Wenn Du jetzt denkst, dass irgendeines dieser Hintergrundobjekte in einem weiteren Bild auftaucht, würdest Du es als “Mehrere Objekte im roten Kreis” markieren, nicht als “Keine der obigen Antworten/guter Kandidat”. Tatsächlich kann ich, wenn ich die Helligkeit auf meinem Monitor ganz aufdrehe, gerade noch das Objekt auf sieben Uhr auch im DSS-Red-Bild sehen, also würde ich das als “Mehrere Objekte im roten Kreis” markieren. (Du könntest anderer Meinung sein.)

4. Wie weiß man, ob ein Objekt “aus dem Kreis herausragt”?

Ein Objekt ragt aus dem roten Kreis heraus, wenn es eindeutig eine Struktur hat, die sich über den roten Kreis hinaus erstreckt. Ein schwacher, feiner Lichthof (Halo), der sich über den roten Kreis hinaus erstreckt, ist ok. Schauen wir uns einige Beispiele an.

Extended_ScreenshotDieses Objekt hat ganz klar eine Struktur, die sich über den roten Kreis hinaus erstreckt. Es sieht aus, als sitze es in einer Wolke – und es könnte sich tatsächlich in einer Wolke aus interstellarem Staub befinden. Unsere Galaxis ist voller interstellarem Staub, der nicht Teil der Staubscheiben ist, nach denen wir suchen. Wir sehen auf Disk Detective oft Objekte, die aus einem ansonsten staubfreien Stern bestehen, der nur zufällig vor (oder hinter) einem unverbundenen Klecks aus interstellarem Staub ist.

Hier ist ein weiteres Beispiel (rechts), das über den roten Kreis hinausragt, ein wenig feiner. Siehst Du den schwachen Wisch von Blau, der das Objekt im roten Kreis mit dem Objekt in der unteren linken Ecke verbindet? Das ist schlecht. Es ist ein Zeichen dafür, dass das SED durch Licht von diesem Objekt in der unteren linken Ecke verunreinigt wird. Manchmal muss man die Augen zusammenkneifen und die Helligkeit des Monitors maximal aufdrehen, um diese Objekte zu sehen.

5. Wie sehen Artefakte aus, und wo kann ich Beispiele dafür finden?

DSS-Bilder sind von gescannten Fotoplatten aus Glas. Verunreinigungen wie Staub oder Kratzer können dazu führen, dass manche DSS-Bilder seltsame Objekte enthalten. Beispiele solcher Artefakte kannst Du hier in dieser Diskussion finden. Auf manchen Bildern kannst Du sogar Spuren sehen, auf denen ein Flugzeug während der Beobachtung darüber geflogen ist. Hier sind einige Beispiele dafür.

6. Es gibt keinen “Zurück”-Knopf. Was passiert, wenn ich einen Fehler gemacht habe?

Es ist in Ordnung, wenn Du ab und zu einen Fehler machst. Jedes Bild wird von mehreren Disk Detectives angeschaut werden, bevor das endgültige Ergebnis veröffentlicht wird. Dieser Prozess führt im Allgemeinen zu Ergebnissen, die bemerkenswert frei von Fehlern und Voreingenommenheit sind – viel mehr, als wenn ein einzelner Wissenschaftler die Daten alleine untersucht. Also mach Deinen Weg und versuche es erneut!

Hier ist ein interessantes Beispiel (auf Englisch), wie ein anderes Zooniverse-Projekt (Galaxy Zoo) die Klassifikationsdaten dazu benutzte, um die menschliche Voreingenommenheit zu kalibrieren und zu entfernen, die ansonsten vielleicht unentdeckt geblieben wäre.

7. Wo kann ich Beispiele für die häufigsten SEDs finden?

Hier ist ein Blog-Post mit Beispielen für einige der häufigsten Arten von SEDs (auf Englisch).

8. Wo kann ich mehr Informationen über das Objekt finden, das ich klassifiziere, vom “Bild” abgesehen?

Um mehr Informationen über das Objekt zu erhalten, das Du gerade betrachtest, schau Dir die “Talk”-Seite an. Hier findest Du das “Spectral Energy Distribution”-Diagramm (SED) des Objekts und einen Link zu einer Informationsseite über das Objekt in einer Datenbank namens “SIMBAD”. Du kannst auch versuchen, Deine Lieblingsobjekte auf der BANYAN-II-Seite einzugeben. Hier findest Du mehr Informationen über jedes dieser Hilfsmittel.

Ich schlage Dir vor, dass Du mit der “Talk”-Seite des Objekts anfängst. Um auf die “Talk”-Seite eines Objekts zu gelangen, klicke auf das “Talk”-Symbol.Talk_Icon

Auf der Talk-Seite findest Du das SED des Objekts und einen Link zu SIMBAD. Das SED sagt Dir, woher die Energie in Abhängigkeit von der Wellenlänge kommt; es ist ein wichtiges Hilfsmittel, um Scheiben zu erkennen und zu klassifizieren. Hier findest Du eine grundlegende Einführung in SEDs (auf Englisch). Und hier sind einige Beispiele für gängige SEDs, die Du auf Disk Detective sehen wirst (auf Englisch).

SIMBAD (“Set of Identifications, Measurements, and Bibliography for Astronomical Data”, also “Satz aus Identifikationen, Messwerten und Bibliografie für astronomische Daten”) ist eine große Datenbank für astronomische Objekte; Du wirst etwa für die Hälfte der Objekte auf Disk Detective Einträge in SIMBAD finden. Hier findest Du mehr Informationen über SIMBAD (auf Englisch).

Wenn Du mehr über ein Objekt erfahren möchtest und es nicht in SIMBAD findest (SIMBAD gibt als Ergebnis ein “No Astronomical Object Found” oder “NoAO” aus, also “kein astronomisches Objekt gefunden”), versuche es mit einer anderen Datenbank namens “VizieR”. Gib bei VizieR einfach die Koordinaten ein, die auf der SIMBAD-Seite mit “No Astronomical Object Found” erscheinen und lege den Suchradius auf etwa 2 Bogensekunden (2 arcseconds).

Beachte aber, dass VizieR viele verschiedene Datenbanken gleichzeitig abfragt und überflüssige oder sogar sich widersprechende Informationen anzeigen kann! Wenn Du widersprüchliche Informationen auf VizieR siehst, überprüfe die Daten der Quellenangaben – es ist im Allgemeinen besser, der neuesten Quellenangabe zu vertrauen. Beachte auch, wenn sich im Suchradius mehrere Objekte befinden (die Standardeinstellung ist 10 Bogensekunden, “10 arcsec”), dass sie alle auch in der Ergebnisliste auftauchen werden. Du musst also aufpassen, dass Du Dir das richtige Objekt ansiehst.

VizieR enthält jede Menge Informationen, die wir brauchen, um unsere Folgebeobachtungen zu planen: die V-Magnitude, die J-Magnitude, den Spektraltyp und die Variabilität im V-Beobachtungsband. Wenn Du also einen guten Kandidaten findest, wäre es hilfreich, diese Informationen aus VizieR zu besorgen und in einem Kommentar auf Talk zu erwähnen. Denk daran, wie ein guter Wissenschaftler eine Quellenangabe und Fehlerbalken anzugeben!

BANYAN II ist ein weiteres hilfreiches und kostenloses Online-Werkzeug, das sich nicht auf der Talk-Seite findet. BANYAN II sagt Dir, ob ein Stern wahrscheinlich Bestandteil von einer von mehreren möglichen bekannten Gruppen junger Sterne ist. Das ist wichtig, denn wenn er Bestandteil einer dieser Gruppen ist, gibt uns das eine gute Schätzung für das Alter des Sterns – und das sagt uns, dass der Stern ziemlich jung ist (weniger als 100 Millionen Jahre alt). Wenn der Stern jung ist, heißt das, dass die Planeten, die ihn umkreisen, jung – und heiß – sind und deswegen einfach abzubilden! Wenn BANYAN II Dir also sagt, dass der Stern zu einer dieser Gruppen gehört, wird er wahrscheinlich ein gutes Ziel für die Suche nach Planeten sein.

Wenn der Stern in SIMBAD aufgeführt ist, musst Du einfach nur den Namen des Sterns in BANYAN II eingeben. Klicke auf “RESOLVE” und dann auf “SUBMIT” und BANYAN II gibt Dir eine Antwort in Form einer Liste von Prozentwerten aus.

Wenn ich zum Beispiel “Bet Pic” (also Beta Pictoris) eingebe, erhalte ich etwa dieses Ergebnis:

0.00 99.87 0.00 0.00


0.00 0.00 0.00 0.13

Mit anderen Worten: der Stern Beta Pictoris ist mit 99,87% Wahrscheinlichkeit ein Mitglied des Beta-Pictoris-Bewegungshaufens. Keine große Überraschung.

Wenn ich allerdings Gam Pic eingebe, erhalte ich dieses Ergebnis:

0.00 0.00 0.00 0.00


0.00 0.00 0.00 100.00

Mit anderen Worten: Gamma Pictoris ist mit 100% Wahrscheinlichkeit ein “field star”. Das ist ein Stern, der zu keiner Gruppe und keinem Sternhaufen gehört. Beta Pictoris wird natürlich von einem gut bekannten direkt abgebildeten Planeten umkreist. Gamma Pictoris dagegen nicht.

Wenn der Stern nicht in SIMBAD ist, ist etwas mehr Aufwand notwendig. Du musst dann die Angaben zu RA, Dec, Eigenbewegung (proper motion) usw. selbst eingeben. Du kannst diese Angaben aus VizieR bekommen.

Wenn das Ergebnis in BANYAN II darauf hindeutet, dass ein Stern aus Disk Detective mit mehr als 80% Wahrscheinlichkeit ein Mitglied von einer dieser Gruppen ist (außer “field star”), möchten wir das gerne wissen. Denk daran, einen Kommentar dazu auf der Talk-Seite zu hinterlassen!

9. Warum gibt es mehr Bilder eines Objekts als Kurvenpunkte im SED?

Die Kurvenpunkte im SED zeigen, wie hell das Objekt in Abhängigkeit vom Wellenbereich ist – diese Art Daten wird “Fotometrie” oder Lichtstärkemessung genannt. Die Fotometrie für die meisten Disk-Detective-Objekte ist im nahen Infrarotbereich und mittleren Infrarotbereich ziemlich zuverlässig. Diese Fotometriedaten stammen aus den 2MASS- und WISE-Datensätzen; das siehst Du im SED auf der Talk-Seite. Die Fotometrie für kürzere (“optische”) Wellenlängen hat dagegen eher durchwachsene Qualität, also haben wir sie vorerst aus den SEDs auf der Disk-Detective-Webseite herausgelassen.

Wir werden aber die optische Fotometrie in die SEDs der von uns entdeckten Scheiben integrieren müssen, um bessere Modelle zu erstellen. (Das wäre übrigens ein gutes Projekt nebenbei, wenn jemand Interesse hat!)

10. Wie lege ich eine Sammlung meiner Lieblingsobjekte an?

Collect_buttonNachdem Du die Bildserie auf der Hauptseite durchgesehen hast, klicke auf das “Talk”-Symbol neben dem Stern-Symbol. Das bringt Dich zur Talk-Seite. Oben links siehst Du “collect” (Sammeln), klick darauf, um ein Objekt einer Sammlung hinzuzufügen. Du kannst dann wählen, ob Du es einer Sammlung namens “Favorites” (Favoriten) hinzufügst, oder Du kannst eine neue Sammlung anlegen (durch Klick auf “Start a New Collection”).

11. Warum kann ich in den Disk-Detective-Bildern keine Planeten sehen?

In diesem Blog-Post findest Du die Erklärung (auf Englisch).

12. Warum sind DSS-Bilder so verpixelt? Warum gibt es kein DSS2-Bild?

Manchmal sehen Bilder aus der Digitized Sky Survey (DSS) so verpixelt wie ein billiges Videospiel aus den 1980er Jahren aus. Das sieht zum Beispiel so aus (siehe auch das Bild rechts). Das passiert, wenn es kein helles Objekt im FeldPIxelatedDSS_Screenshot gibt und nur das Rauschen des Detektors zu sehen ist. Das kann passieren, wenn das Objekt, das wir betrachten, entweder kalt ist oder hinter einer Staubwolke liegt (z.B. wenn es sich in der Ebene der Milchstraße befindet). Es sollte aber trotzdem in den Bildern mit längerer Wellenlänge auftauchen. Mehr Informationen über Abweichungen in der DSS findest Du auf dieser DSS-Webseite (auf Englisch).

13. Wie groß sind die Bilder, die wir auf Disk Detective sehen?

In der Astronomie messen wir die Größe von Objekten am Himmel in Bogensekunden und manchmal in Bogenminuten. Wenn Du uneingeschränkt gut siehst, heißt das, dass Du Buchstaben lesen kannst, die fünf Bogenminuten hoch sind, was 300 Bogensekunden entspricht. Hier ist ein Wikipedia-Artikel mit mehr Informationen über diese kleinen Winkeleinheiten.

Die Bilder auf Disk Detective haben eine Länge von einer Bogenminute (60 Bogensekunden). Der rote Kreis misst 10,5 Bogensekunden und das Kreuz 2,1 Bogensekunden. Jemand müsste eine zwanzigfach bessere Sehkraft als der Durchschnitt haben, um ein Objekt mit der Größe des roten Kreises zu sehen.

14. Warum scheinen die meisten Bilder in längeren Wellenlängen größer zu werden?

Hier beantwortet ein Blog-Post diese Frage (auf Englisch).

15. Manche Objekte sind in den blauen Bildern deutlich größer als im nahen Infrarotbereich. Deutet das darauf hin, dass sie wahrscheinlich eher Nebel oder Galaxien anstatt Sterne sind? Wie sollten wir mit ihnen umgehen?

Manche Objekte werden in den blauen Bildern viel größer aussehen, weil sie in diesen Wellenlängen heller sind und den Detektor (oder die Fotoplatte) sättigen. Wenn das passiert, gelangen die mittigen Pixel im Bild ans Limit und das Objekt beginnt viel größer auszusehen, als wenn der Detektor sich in linearer Weise verhalten würde. Wie schon bei der Antwort zur häufig gestellten Frage 2. (“Was ist die Grenze für ‘rund’?”) können diese Objekte auch Beugungsspitzen und anders verzerrte Formen zeigen.

Das ist alles ok und sollte Dich nicht davon abbringen, etwas als “guten Kandidaten” zu klassifizieren! Die meisten Objekte, die so gesättigt sind, sind Sterne und sind manchmal die besten Objekte für weitere Nachverfolgung, weil sie lichtstark sind.

16. Wie trete ich der Gruppe der fortgeschrittenen Benutzer (Advanced User Group) bei?

Wenn Du mehr als 300 Klassifikationen bei Disk Detective gemacht hast und bereit bist, Dich mehr zu engagieren, schicke eine E-Mail an und frage danach, der “Advanced User Group” beizutreten. Wir würden uns sehr freuen, Dich zu begrüßen!