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.
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.
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.
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.
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.
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.
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: CircumstellarDisks.org. 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 CircumstellarDisks.org.
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!
Hi, all. Steven Silverberg from the science team here. Rather than my blog posts appearing under Marc’s name, I’ll be writing on this name from now on. It should make the blog a bit easier and less confusing to read.
Two weeks ago, I was lucky enough to observe on the Stratospheric Observatory For Infrared Astronomy (SOFIA). Here’s a summary of what we did, and what it was like.
SOFIA is a 747 with a custom hatch in the back and a telescope mounted inside, allowing us to observe from 40,000 feet. That altitude is above the primary part of the atmosphere that blocks infrared light, which means the telescope can observe at wavelengths longer than the ones we see in our Disk Detective WISE data, but shorter than the submillimeter wavelengths we’ve observed at with the James Clerk Maxwell Telescope. This neatly fills in a gap in our SEDs, giving us a clearer picture of how dust is distributed in these systems.
Last SOFIA proposal cycle, we submitted two proposals, and one was accepted for “do if time” status. This proposal was to get 53 micron data on a set of our main sequence A stars, as well as those identified by other projects (such as Patel et al. 2014). Our first set of observations was scheduled for May 9-11, so John Debes from the science team (and Space Telescope Science Institute) and I flew to California to ride along.
The plane itself is pretty impressive. 747s are big.
SOFIA is a working plane, so everyone onboard is piped in to the comms system. Wearing a flight comms headset makes you look important.
Because they had space, I was given permission to ride along in the cockpit for takeoff. Unfortunately, our first flight had to be scrubbed before takeoff, due to issues with some of the engine gauges.
I did, however, get to ride in the cockpit for takeoff on the second night. Sunset is really pretty when looking through the windshield of a 747.
The main cabin of SOFIA feels a little bit like mission control; lots of people looking at lots of monitors, all in rows. On these flights, we had SOFIA flight safety crew, the mission directors, telescope operators, and the team that built the HAWC+ instrument we were using.
We proposed to look at objects with an instrument called HAWC+ (High-resolution Airborne Wideband Camera-plus). This is a far-infrared camera, designed to probe long wavelengths. If the detector is sensitive enough and our target bright enough, we would be able to see light from our star+disk systems to add another point to our SED for that DDOI, but at worst we can get upper limits on what flux there is, letting us at least constrain the system.
HAWC+ has to come into the cabin through the main doors of the airplane. It’s engineered to fit through with 1/8 of an inch of clearance on either side.
SOFIA helpfully has lots of posters along the bulkhead about how it works…
…and some of the science it does
It also has one about how NASA came to acquire the plane.
Sunsets were impressive through the regular windows, too.
So was the Moon on our second flight.
Our last flight lasted long enough that the Sun was rising as we went into our descent.
The hangar the program is based out of is (unsurprisingly) huge.
All in all, it was a very educational, very informative, very fun trip on SOFIA. Thanks to you all for contributing to this project to make things like getting data from it feasible.
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.)
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 email@example.com.
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!
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…
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.
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 firstname.lastname@example.org.
Nice work, everybody! And we’re just getting started. Stay tuned for more papers later this year.
Disk Detective Milton Bosch stopped by NASA Goddard Space Flight Center this month to meet with some of the science team and see the James Webb Space Telescope being built. What ended up happening that day we never could have guessed! Here’s the story, in his words.
My Day at NASA Goddard Space Flight Center
by Milton Bosch Nov.20, 2015
Greenbelt, Maryland has always held a special place in my heart and mind. I met and courted my wife there and lived three wonderful years in a unique New Deal era city in suburban Maryland outside Washington, DC. It has a lake and even camping at Greenbelt Park, part of the National Park system. Best of all, NASA in its wisdom had chosen Greenbelt as the site
for its first Space Flight Center. NASA Goddard opened on May 01, 1959. We had it all.
I’d always look at the guarded entrance across from our shopping center, and wonder, What is going on inside those gates? Really cool stuff, no doubt. That was in 1981; I was in medical school and there was almost zero chance I’d ever be invited there. Even after moving to California for residency training and my career in internal medicine, my NASA Goddard
memories were kept alive whenever I had a faint recollection. When a good friend named Willy got a job at Goddard as a machinist in 2010, the connection deepened a wee bit. I could picture myself inside if Willy could get permission to bring a visitor. That snippet of hope left when Willy left NASA Goddard after a couple years.
Fast forward: It’s now November 04, 2015 and I’m on a Google hangout call with the science team of Disk Detective, a citizen science project run by NASA. Months earlier, a NASA email arrived announcing a new citizen science project on January 30, 2014 , with a grant from The Zooniverse. Disk Detective’s goal was to locate protoplanetary disks – very early solar
systems – around young stars, and debris disks around more mature ones. I thought, “Discover new solar systems and planets and help learn how they form? I’m in!” I thought “in” was just doing classifications of objects, using the Disk Detective flip-book to triage them into two basic categories: a good candidate, or flawed (and reasons why). After doing many classifications came the invitation to become a superuser from principal investigator Marc Kuchner. As such, I learned how to navigate the astronomy catalogs, and choose promising objects for the main spreadsheet and hone my classifying skills. Step by step, with lots of mentoring and greater responsibilities, I was eventually asked to join the science team and here I was, sitting at my computer on November 5th for our weekly Google hangout with the science team.
I mentioned to Marc that I had won two free concert tickets to Madison Square Gardens for Nov. 7th, and would be staying near Greenbelt in Crofton, MD. Then Marc asked if I’d like to drop by on Nov. 6th for a tour of NASA Goddard Space Flight Center. Two days later I fulfilled my dream. What came later was a big surprise for everyone.
We started out with meeting everyone on the Disk Detective team at NASA Goddard. It was great finally meeting Marc Kuchner, PI, and graduate students Steven Silverberg and Shambo Bhattacharjee. We did a quick tour of the ground level, and then visited the offices of each. Then, upstairs to see the world’s largest clean room, where the James Webb Space Telescope (JWST) is under construction. We exited the elevator to discover a VIP tour in progress, and it slowly dawned on me that I was looking at North Dakota senator Heidi Heitkamp. She was not just any US Senator; she was a senator I liked and had supported her campaign. I whispered to Marc that I knew a bit about Senator Heitkamp, so he asked me to ask her a question about citizen science. I said, OK, and waited for my opportunity.
Just when it seemed like the right moment would never appear, I saw a raised hand asking if we could talk about citizen science. Senator Heitkamp walked over and introduced herself to each one of us, asking our names, where we lived, what our jobs were, and what we did before coming to NASA Goddard. She was pleased to meet a supporter from Napa, California. She wanted to know my journey from organic chemist, to medical doctor, to having to go on full disability, to finding and joining Disk Detective. So I told her my story of today being the fulfillment of a 34 year-old dream, all made possible by joining Disk Detective almost two years earlier, and a 1:20,000 chance of winning 2 free concert tickets to Madison Square Gardens.
While we talked, the cameras were snapping away and all-in-all, I think we got to spend 15 minutes on Disk Detective and citizen science. It was an unlooked-for opportunity to get the word out about Disk Detective and citizen science with one of our U.S. Senators and it could not have gone better. We were glowing for the rest of the day from the encounter.
Then the room cleared, and we got to see what we had come upstairs for: the James Webb Space Telescope under construction. (One of the goals of Disk Detective is to find targets to propose to observe with this telescope.) We could see the frame, the folded wings, and folded arm for the secondary mirror. On catwalks 80 feet above the crew sat a row of flat dewar flasks, each containing one hexagonal mirror. Launch date is less than 3 years away – October, 2018. Giant rolls of shrink wrap were placed all about for final sealing before JWST’s journey to the launch vehicle. I looked at everything in the room visible from our vantage point and then went downstairs and peeked through an entrance door window. No photos are allowed through that window, nor inside either.
Next stop was one of the “testing rooms”; though I’m sure it has a formal name. It had an 8 story high egg-shaped metal container, filled with liquid nitrogen for starters. Inside that was another cryogenic container filled with liquid helium. Every single piece, every instrument, every device must survive that environment before it can be trusted for launch. After all, they must function at extremely low temperatures. But more terrors awaited the equipment and instruments that go into space.
Nearby was a huge room with a centrifuge that dwarfed a blue whale. It was like the room where the centrifuge scene from The Right Stuff movie was filmed, but this centrifuge has a different purpose. In order to test equipment properly (not people), the centrifuge reaches up to 15 G’s of acceleration, helping insure against failure in the most stressful environments imaginable. Steven said it would tear a human to pieces.
Next door to that was a huge acoustic testing room with a 7 or 8 foot “tweeter” and a 12 foot “woofer” with a maximum combined sound intensity of 150 decibels. No humans are allowed inside that lethal chamber. An adjacent room held the machinery that powered the 150 decibel monster. A six inch hose for pressurized nitrogen powered the tweeter, and emitted so much of the simple asphyxiant that there is no admittance during testing. We paused our tour for a relaxing lunch in the cafeteria, and then filled time while Marc had teaching duties. Those duties now completed, we all met in Marc’s office, where all the Google hangouts take place (with other scientists joining from Adler Planetarium, The Space Telescope Science Institute, University of Oklahoma, and more).
We spent an hour discussing ways to improve our sound recordings and other technical issues, as well as more important problems, like finding a replacement llama doll for Marc’s very young son, should he lose his beloved cozy-coze. Then I was presented with a highly coveted Disk Detective coffee mug, and we took photos of a poster where my name appeared as co-author, alongside the names of five other citizen volunteers like myself. Then it was time to go.
It was a truly great day, full of the unexpected, and a real pleasure meeting some of the science team in person. Never give up on your dreams! Disk Detective will take you as far as you want go and has all types of support while you navigate the learning curve…all the way up to co-authorship of scientific papers.
Bernard Lyot was a French astronomer who invented a tool called a “coronagraph” that’s useful for making images of disks and exoplanets. A few weeks ago, I went to a conference in Montreal, called “In the Spirit of Lyot 2015” named in his honor, and I learned lots of cool new stuff about images of disks and planetary systems. Here are some of the highlights.
First of all, Disk Detective superuser Manon Gingras came to the conference and I got to meet her! Manon was spending her last few days in Montreal before she moved to Australia, and she drove downtown to the conference hotel to spend the afternoon with us. While she was at the conference, she did an interview with a reporter from the French language magazine Le Devoir about Disk Detective. Manon described her experience at the conference in this blog post. (Don’t worry, when Manon says “gunning down” she is not talking about anything violent–it’s just an expression.)
Disk Detective science team member Dr. Thayne Currie described a debris disk around the star HD 115600 that he imaged for the first time. It’s a beauty, an eccentric ring of debris about 15 million years old around a star just about 50% more massive than the sun, essentially a younger version of the Kuiper Belt in our solar system. And–arrgh!–this star is in the Disk Detective catalog, just nobody had gotten around to looking at it yet. So we might have been able to claim this as one of our Disk Detective discoveries too. Oh well. Next time.
Dr. Erika Nesvold gave a talk about her new dynamical models of the Beta Pictoris debris disk. They show what happens when a planet, embedded in a debris disk, orbits very slightly out of the plane of the disk. Here’s the press release about her results and the YouTube video. You might remember Erika if you were around during the first week after Disk Detective’s launch; she pitched in to help answer questions on Talk.
And last but not least, the Gemini Planet Imager (GPI) team announced a new directly-imaged extrasolar planet, 51 Eridani b, located inside a debris disk. You have probably heard of the many hundreds of planets discovered by NASA’s Kepler space telescope; those planets have been inferred from the way they sometimes block part of the light from the stars they orbit. Directly imaged planets–planets whose light we can collect like 51 Eridani b–are much rarer. And most of these directly-imaged planets orbit within debris disks, one kind of disk that we’re searching for at Disk Detective. So when we search for disks, in a way, we’re searching for planets too!
Everyone I spoke to at the meeting was interested in learning about Disk Detective, and eager to hear what we have found. I showed off some of the work we did following up our Disk Detective Objects of Interest (DDOIs) with RoboAO, and several colleagues asked to collaborate with us as a result. Hugo, Michi, Ted, Joe, Lily, Katharina, and Milton hustled to get this data analysis work done in time for me to show off. So the science of disks and exoplanets marches on…and we’re right in the thick of it. Keep up the good work, everybody!
A list of 102 interesting objects that you helped pick for follow up (let us call them Disk Detective Objects of Interest, or DDOIs) shows that many of the stars with disks we locate will be A dwarfs or K giant stars. We don’t yet know all the spectral types of the DDOI stars precisely, but you can see the distribution of the types we do know in the figure below. The peaks correspond to A dwarfs and K giants.
So what are A dwarfs and K giants? “A” dwarfs are very hot, fast spinning and blue stars that are younger and brighter than “G” stars such as our Sun. The bright stars Sirius and Vega are some well known A dwarfs. Many of the best studied debris disks are around A dwarfs.
What are these “K giants”? K giants and A dwarfs are two sides of the same coin. Let’s talk a bit about the life cycle of a typical star.
Most ordinary stars like our Sun burn hydrogen fuel for many millions of years. Once all the hydrogen is used up however, the star balloons in size and becomes a red giant. In the far future when our own Sun becomes a red giant, it will become so big that it will swallow up Mercury, Venus and possibly the Earth. Giants also tend to steadily lose a lot of their own mass all the time. This is because hot winds are blowing off the gas that is part of the star. (This hot gas is tricky because it might be mistaken for a dusty disk)
K giants are former A stars that have evolved for hundreds of millions of years. Like the sun, they have burned through their hydrogen, and ballooned up in size. Both A and K stars are about twice as massive as our Sun.
K giants are also really interesting because Jupiter-sized exoplanets orbiting these old, giant stars have been found to be more common than Jupiter-sized exoplanets orbiting less massive stars that are still on the main sequence. These exoplanets around K giants have been found by the popular radial velocity (Doppler shift) method.
Also, some of these K giants have debris disks, sometimes even dustier than their younger counterparts. This is surprising, because giants are very bright and light from the star exerts radiation pressure on small dust particles that ought to blow the dust away, or cause them to slow down and spiral into the star and be swallowed up.
So where is the dust around these K giants coming from? Nobody really knows yet, but there are several hypotheses. One is that dust is coming from the star itself. Another is that the dust is in fact interstellar dust in our galaxy. A third is that giants are breaking up more comets. Whatever the cause, we have a lot of K giants in our list of DDOIs that potentially have dusty disks–so once we can follow these up with telescopes we will be able to help solve this mystery.
Dawoon Jung (@dirkpitt2050) is a graduate student at the International Space University currently at NASA Goddard Space Flight Center doing a summer internship with the Disk Detective team. He was born in Korea, and is interested in exoplanets and space flight.
We’re excited to announce that Disk Detective has been translated into Mandarin Chinese–both simplified and traditional character fonts! Many thanks to Ruobing Dong at the University of California, Berkeley Astronomy Department and Mei-Yin Chou at Academia Sinica’s Institute of Astronomy & Astrophysics (ASIAA) for the translation work and to Chris Snyder at Zooniverse for the technical work.
Here is a brief description of Disk Detective in traditional character Chinese and then followed in English:
為了找到這些盤，我們結合了數十萬張來自美國太空總署（NASA）的廣域紅外線巡天探測（WISE）任務的影像。已經有很多科學家搜尋來自 WISE的資料並試著用電腦找出這些盤。然而這些盤容易跟星系、小行星、星際物質團塊和其他天體搞混，科學團隊檢視後發現必須用人眼來辨識這 些資料才行。
在尋盤偵探（DiskDetective.org） 中，有了你的協助，這些被辨識出來的盤將能用來建立一個最大的盤資料目錄。NASA的James Webb太空望遠鏡和其他望遠鏡將用這個目錄為主要目標來尋找系外行星。我們找到的這些盤將有助於了解太陽系的過去跟未來。
Planets like the Earth form within disks of gas, dust, rock and ice grains that surround young stars. We need your help to find more examples of these planet-forming disks so we can locate extrasolar planets and better understand how they grow and mature.
To find these disks, we’re combing through a catalog of hundreds of thousands of sources from NASA’s Wide-field Infrared Survey Explorer (WISE) mission. Many scientists have been searching through the data from the WISE space telescope to find disks using computers. But the disks are mixed in among galaxies, asteroids, clumps of interstellar matter, and other contaminants. And each team that has looked through the data has found that every source has to be verified by eye.
With your help, at Disk Detective.org we will produce a catalog of verified sources many times bigger than any other catalog. This catalog will yield key targets for NASA’s James Webb Space Telescope and other telescopes to search for exoplanets. The disks we find will help us understand the history and future of our solar system.