Send us your questions through the Talk page! We'll pick the most frequently asked ones and answer them here.
Brown dwarfs are dim, star-like objects that haven't quite reached a high enough mass to consistently fuse hydrogen in their core. However, they are just massive enough to fuse deuterium -- an isotope of hydrogen that is easier to fuse together due to its higher mass. As a result, they emit only a tiny amount of light (mostly in the infrared spectrum) which is much less than a typical star. Brown dwarfs are also much cooler than the Sun (by factors of ~10)! The aim of this project is to detect these dim objects within our cosmic neighborhood. This is why we call them "Cool Neighbors".
The Backyard Worlds: Planet 9 project was primarily designed to search for a hypothesized planet (referred to as Planet 9) in the outer reaches of our own solar system. Because such a planet would move across the sky very quickly, the Backyard Worlds: Planet 9 flipbooks show "difference images" -- images where all of the unchanging stars/galaxies are subtracted away, leaving only the celestial objects that move very fast (or change in brightness with time!). This is not ideal for finding brown dwarfs in the Sun's neighborhood, since they move across the sky more slowly than Planet 9. To optimize our search for brown dwarfs, Cool Neighbors therefore shows sky images without any subtraction -- all the normal stars and galaxies are still present. This provides a more straightforward and intuitive way of seeing how a sky patch looks over time.
Another key difference relative to Backyard Worlds: Planet 9 is that Cool Neighbors is a "targeted" search. Whereas Backyard Worlds: Planet 9 shows random sky patches, Backyard Worlds: Cool Neighbors shows sky patches centered on brown dwarf candidates pre-selected via machine learning. Because we at Cool Neighbors expect our candidates to be centered within each subject, this also allows us to use a much narrower, more zoomed in field of view than that of Backyard Worlds: Planet 9 subjects, enabling more detailed visual inspection.
While the existing Backyard Worlds: Planet 9 project has been tremendously helpful towards the discovery of new brown dwarfs, its visual inspection workflow is not optimized for brown dwarf discovery. With the more optimized workflow of Backyard Worlds: Cool Neighbors, we may be able to uncover hundreds or thousands more substellar objects!
If you were able to see these objects in person, it's theorized that they might look like Jupiter and may even have a purple-red glow.
However, because brown dwarfs are so small and emit so little light, these objects are very hard for us to detect. In the telescope images we need your help scouring, brown dwarfs may appear as small dots moving across a field of otherwise static stars. They may be slightly orange, although that alone is not a determining factor. Check out the field guide (the small tab on the far right of your screen) for some examples on what a brown dwarf looks like!
Compared to normal ("main sequence") stars and galaxies, and even image artifacts, brown dwarfs are very rare. For instance, WISE has detected billions of galaxies and normal stars, but probably only a few thousand brown dwarfs. To discover a new brown dwarf, you'll likely need to look through roughly 100-500 flipbooks. Approximately 10% of our flipbooks contain previously discovered moving objects, to help you get a sense for what a real mover will look like and to help our research team understand the accuracy of classifications we receive.
Getting Started: Click the CLASSIFY tab in the top right. You will be directed to our current classification workflow! From here, you can help us determine whether the stars you see in the frame are brown dwarfs.
Click the arrow at the bottom left of the image to begin the animation, and watch for any stars that seem to move across the frame. You can pan around and zoom into the images using the tools on the right hand bar, or using your mouse wheel (PC).
For more help, you can click the tutorial or "Need some help with this task?" button. You can also reference the field guide on the right hand side!
I think I found a mover. What should I do now? The first thing to do is check if the mover has been previously published in the astronomical literature using the tools described below. If you find a mover that is not listed in SIMBAD or Gaia[*], please fill out our submission form! If you don't fill out the form, we will learn about your discovery anyway from your classification, but it might take longer for us to get to it and research it.
[*]If a mover is in Gaia with reported Gaia parallax and proper motion measurements, then we consider that to be an already discovered moving object, as it is likely to have appeared in catalogs/papers such as the Gaia Catalog of Nearby Stars (GCNS) if it's close to the solar system. If you've found a mover that's in Gaia but lacks Gaia parallax or proper motion measurements, then this can be submitted. Note however that the Gaia detection generally implies a relatively warm temperature and hence a relatively low likelihood that such a mover will be targeted for high-priority follow-up observations by the Cool Neighbors science team.
How do I use WiseView? Perhaps the easiest (and quickest) way to check if an object has already been published is by using WiseView. WiseView is an online tool built to view flipbooks of WISE data similar to the subjects you are viewing on Zooniverse. However, unlike the Zooniverse flipbooks, in WiseView you have the ability to change a number of different settings that are fixed in Zooniverse. These include the minbright and maxbright parameters (which set the contrast of the image), the sliding window (which controls how adjacent frames are blended into each other to reduce noise), and the Gaia overlay. Gaia is a database of known objects in the night sky.
We've included a link to the WiseView site for each subject in the metadata tab. When you click this link, the Gaia overlay is on by default. If you find a mover in a Zooniverse flipbook, consider checking WiseView to see if a green dot appears over it. If this happens, it means that the object is already known in the Gaia database. If there's no green dot, you may have found a new object! Check the other databases below, and Consider filling out a Move-In form if the object is not found in Gaia or SIMBAD!
How Do I Use SIMBAD? SIMBAD (the Set of Identifications, Measurements, and Bibliography for Astronomical Data) is a handy, although more complicated, database of astronomical objects used by professional astronomers and a crucial tool for us at Backyard Worlds: Cool Neighbors. This blog post explains in detail how to use it to check whether an object you have found is already known or possibly a new discovery.
We've included a direct SIMBAD link to the object you are viewing on Zooniverse in the subject metadata. You can access it by clicking the (i) button on the bottom right of the flipbook, and then clicking the SIMBAD link.
If SIMBAD only finds one source on the image you're looking at, it will take you directly to a page of information about that source. Otherwise, SIMBAD will show you a list of astronomical objects listed in order of their distance from the center of the field of view. Click on the links to learn more about the objects that SIMBAD finds! If there are no sources in SIMBAD, you may have found a brand-new object! When discussing subjects in TALK pages, consider using the #insimbad or #notinsimbad tags, respectively.
SIMBAD uses a long list of abbreviations in its tables. For example, PM* = high proper motion Star, BD* = brown dwarf, BD? = brown dwarf candidate, WD* = white dwarf. You can learn more about SIMBAD from this Users Guide.
One of the most useful features of SIMBAD is that for each object in the catalog, it pulls up a list of papers that have been written mentioning that object. Scroll down and 3/4 down the page you should see "References". You can click "sort references" and see the titles of papers where your favorite object has been mentioned or discussed, if there are any. Be sure to browse through these; your favorite object may already be the focus of a huge international debate--or it may just have played a bit part as a calibrator or an astrometric reference.
How Do I Use VizieR? If you can't find what you are looking for in SIMBAD, you can use VizieR to query a longer list of astronomical catalogs--almost every catalog that has been published! You'll find a much more thorough introduction to VizieR in this blog post. But here are a few basic tips.
Like with SIMBAD, you can find a VizeR link to the object you are viewing in Zooniverse in the metadata tab of each subject.
Unlike SIMBAD, VizieR gives you LOTS of source lists, one for each of the many catalogs it searches. Each list is in order of distance from location you searched (either the coordinates you estimated, or the center of the field of view). Each catalog it searches has its own special focus and caveats, so you may have to do some reading to get the most from this powerful tool. Try combing the query results for references to "proper motion" since you are most likely to have identified a moving source. E.g. you can search the page for the letters "pm" and look for objects with proper motion higher than 100 mas/yr or so. You'll often see "pmRA" for proper motion in Right Ascenscion and pmDE for proper motion in declination. If you find something that's not in VizieR, please flag it on TALK with the #notinvizier hashtag.
Note: if you find your object on VizieR but not in SIMBAD or Gaia, please submit it to Move-In anyway.
Note: do not trust the proper motions listed in the AllWISE catalog on VizieR. They are often unrealistically high, due to a large amount of measurement noise.
How big are the images I'm looking at? Each image is 43 x 43 pixels, and each pixel is 2.75 arcseconds across. So the images are approximately 120 by 120 arcseconds, or equivalently, 2 by 2 arcminutes or 0.03 by 0.03 degrees.
What should I do if I see more than one mover in a flipbook? If you see more than one mover, respond "yes" to the question as you would for a single mover. You might want to check the WiseView and SIMBAD links in the metadata to see if these movers are already known. If not, consider submitting a Move-In for the objects!
What should I do if I see a mover but it's not near the center? We phrased our classification question in a way that we hope will make it as easy as possible for you to spot most movers. However, our machine learning algorithm isn't always perfect. If you catch a mover away from the center of the image, feel free to respond "yes" as you would normally. Also, consider creating a talk page for that subject.
Dealing with real data provides a set of classification challenges that you, as a brown dwarf hunter, must consider. As such, it is important to be able to tell the difference between artifacts present in the data and the actual brown dwarfs we wish to discover.
Detector noise and defects can masquerade as orange and/or moving sources, and therefore show up as "bogus" brown dwarf candidates. Here's one example, a so-called "ghost" in the WISE data:
Explore this example
It looks very orange, but it has an odd donut-shaped appearance which is different from the shape of stars in the imagery, hence we know it can't be a real brown dwarf. If you follow this link, you can see that this ghost is sourced by a bright star that's just "off the screen" in this animation.
As light enters the WISE telescope, the support beams which hold the secondary mirror cause light to be diffracted. As a result, these artifacts can be seen around bright stars in some of the images you will be searching through. In this example, a diffraction spike from a nearby bright star overlaps another star (the black dot in the middle of the frame):
Explore this example
Click "Explore this example" and try to find the star which is causing this diffraction spike!
While not an artifact, "crowded fields" -- areas of the sky such as the plane of the Milky Way Galaxy with lots of stars -- can be more difficult to comprehend, both for computer programs and for humans. Here's a crowded field example, which also includes an orange-colored brown dwarf near the center, moving toward the bottom right:
Explore this example
While these are the most common types of artifacts, there are several others you may encounter while classifying. Check the field guide for more information!
Is there an in-depth guide about distinguishing between movers versus artifacts and known versus unknown brown dwarfs?
Yes! Expert citizen scientist Leopold Gramaize has provided this incredibly helpful guide with very detailed advice/instructions.
Brown dwarfs are the link between star formation and planet formation. They have physical characteristics which overlap with both stars and planets. By counting their numbers and determining their masses, we can learn about how stars, planets and galaxies form. Cool brown dwarfs are especially handy because we use them as analogs to exoplanets. They are the same size as Jupiter, and sometimes the same temperature as Jupiter or even Earth, yet they are far easier to study than exoplanets because do not orbit bright stars that would overwhelm them with glare. Consequently, we can get very detailed information about their atmospheres, which tells us about their composition, rotation, clouds, storms and even magnetic properties. Some brown dwarfs even have planets that orbit them. Working with you on this citizen science project, we hope to uncover exotic brown dwarfs with cloud features that will help us understand the diversity of atmospheres found in exoplanets. To learn more, read Jackie Faherty's blog post.
We expect to find somewhere between several hundred and 1000 new brown dwarfs through the Backyard Worlds: Cool Neighbors project.
There are approximately 3000 discovered to-date. (source)
Like stars, brown dwarfs are classified by the absorption lines found in their spectra, which are indicators of their surface temperatures. M dwarfs are about 3500-2100 K, L dwarfs are 2100-1300K, T dwarfs are 1300 K to about 600 K, and Y dwarfs are thought to be cooler than 600 K. Since brown dwarfs are all about the same physical size, the lower the temperature, the fainter the brown dwarf. The brown dwarf "types" are a continuation of the sequence of stellar types; the full list of types goes O, B, A, F, G, K, M, L, T, Y. Each type has subtypes, indicated by numbers, which describe more subtle variations in temperature. For example, a T6 dwarf is cooler than an T3 dwarf. Both stars and brown dwarfs can be M dwarfs; brown dwarfs don't generally get hotter than about M6.
A pair of brown dwarfs called Luhman 16 or WISE 1049-5319 is located 6.52 light years (1.99 parsecs) from the Sun; they are the closest known brown dwarfs. Maybe you will discover one that is even closer. This diagram shows the locations of the nearest stars and brown dwarfs:  (NASA/Penn State University)
Essentially, we can 'see' a movement of about 1 pixel, which would roughly correspond to:
2.75 arcseconds / 10 years = 0.275 arcseconds per year.
Proxima Centauri is the closest known star to the Sun. It appears to be the faintest member of a system of three stars, called Alpha Centauri, so it is also called Alpha Centauri C. Does it seem strange that the closest known star is closer than the closest known brown dwarf? It does to us...
Gaia's catalogs quote parallax in units of milliarcseconds. The conversion from Gaia parallax in milliarcseconds to distance from the solar system in parsecs is as follows:
distance in parsecs = 1000 / (parallax in milliarcseconds)
A large parallax means that an object is nearby, and a small parallax means that an object is distant. A Gaia parallax value of 50 milliarcseconds corresponds to a distance of 20 parsecs (~65 light years) from the solar system, which would be very nearby by astronomical standards. A Gaia parallax of 5 milliarcseconds (sometimes abbreviated as "mas") corresponds to a distance of 200 parsecs. Generally, for Cool Neighbors, we are most interested in dwarfs that are within a distance of ~100 parsecs of the solar system. More background information about parallax is available from Wikipedia.