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Scientists have used the Spitzer Space Telescope to find a possible exoplanet or brown dwarf candidate, OGLE-2016-BLG-1190Lb, around 22,000 light years away near the center of the Milky Way galaxy. Spitzer is currently using transit photometry and gravitational microlensing to find exoplanets, a use the telescope wasn't originally designed for. Spitzer recently discovered five of the seven exoplanets around TRAPPIST-1 using the transit photometry method.
OGLE-2016-BLG-1190Lb is likely to be the first exoplanet Spitzer has found in the Milky Way's Galactic bulge using gravitational microlensing. At an estimated 13.4 ± 0.9 Jupiter masses, the object is right near the deuterium burning limit, the boundary dividing large gas giants from brown dwarfs.
The paper explains the significance of the discovery:
The discovery of Spitzer microlensing planet OGLE-2016-BLG-1190Lb is remarkable in five different respects. First, it is the first planet in the Spitzer Galactic-distribution sample that likely lies in the Galactic bulge, which would break the trend from the three previous members of this sample. Second, it is precisely measured to be right at the edge of the brown dwarf desert. Since the existence of the brown dwarf desert is the signature of different formation mechanisms for stars and planets, the extremely close proximity of OGLE-2016-BLG-1190Lb to this desert raises the question of whether it is truly a "planet" (by formation mechanism) and therefore reacts back upon its role tracing the Galactic distribution of planets, just mentioned above. Third, it is the first planet to enter the Spitzer "blind" sample whose existence was recognized prior to its choice as a Spitzer target. This seeming contradiction was clearly anticipated by Yee et al. (2015b) when they established their protocols for the Galactic distribution experiment. The discovery therefore tests the well-defined, but intricate procedures devised by Yee et al. (2015b) to deal with this possibility. Fourth, it is the first planet (and indeed the first microlensing event) for which the well-known microlens-parallax degeneracy has been broken by observations from two satellites. Finally, it is the first microlensing planet for which a complete orbital solution has been attempted. While this attempt is not completely successful in that a one-dimensional degeneracy remains, it is an important benchmark on the road to such solutions.
OGLE-2016-BLG-1190Lb: First Spitzer Bulge Planet Lies Near the Planet/Brown-Dwarf Boundary
Related: Seven Earth-Sized Exoplanets, Including Three Potentially Habitable, Identified Around TRAPPIST-1
Scientists Improve Brown Dwarf Weather Forecasts
(Score: 2) by frojack on Tuesday November 14 2017, @06:54AM (4 children)
Why are they wasting their time ogling stars 22,000 light years away near the center of the Milky Way galaxy. Have they suddenly and secretly invented warp drive or something? Have they exhausted all the life-time-reachable stars?
Stars Stars within 12 Light years of earth. [atlasoftheuniverse.com]
No, you are mistaken. I've always had this sig.
(Score: 2) by takyon on Tuesday November 14 2017, @07:29AM
I assumed they are systematically using the gravitational microlensing [wikipedia.org] technique on thousands of nearby objects, and just happened to get a view of something 22,000 light years away in this case.
Search for "Spitzer Galactic-distribution sample"
http://adsabs.harvard.edu/abs/2016sptz.prop13005G [harvard.edu]
I think what's going on here is that they are aiming Spitzer at objects between Spitzer and the galactic bulge, with the expectation that there is a higher chance of detecting stuff in the bulge using microlensing since the matter is packed closer together.
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(Score: 3, Informative) by takyon on Tuesday November 14 2017, @08:54AM
Here's a story about a Spitzer/OGLE microlensing exoplanet that was found a bit closer:
https://www.nasa.gov/jpl/nasas-spitzer-spots-planet-deep-within-our-galaxy [nasa.gov]
The technique works better when aimed at the bulge:
Spitzer's distance from Earth allows objects to be located using Spitzer + an Earth based observatory:
You asked why they are looking at stars so far away instead of the ones close up. It's because they want to know about the distribution of objects in the center of our galaxy:
For all we know, there are less planets in the galactic center because they interact gravitationally with other stars more often, smash into each other and stars/brown dwarfs, etc.
Also, there's no hurry to observe our solar neighborhood. We have new telescopes coming up in the next 20 years that are going to provide the exoplanet data we really crave: atmospheric and even biosphere detection. JWST [wikipedia.org], WFIRST [wikipedia.org], ATLAST [wikipedia.org]/LUVOIR [wikipedia.org] (whatever it ends up getting called, basically a more direct successor to Hubble than JWST), FINESSE [wikipedia.org], etc. will provide this data.
Don't forget that Spitzer is being used on targets closer to home. It discovered five [spaceflightinsider.com] of the seven known TRAPPIST-1 [wikipedia.org] exoplanets (39.5 light years away).
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(Score: 1, Funny) by Anonymous Coward on Tuesday November 14 2017, @09:19AM
I think it is because once I took a brown dwarf from the near neighborhood, and I tacked it to the side of our shed. Some 8 years later, when we finally moved from that house, the brown dwarf was still attached to the side the shed, and showed no signs of bio-degradation, or of running out of dueterium, for that matter. This is when I thought it might be a good idea to look at some brown dwarfs a bit further afield.
(Score: 2) by takyon on Wednesday November 15 2017, @03:28AM
If you include brown dwarfs along with stars (not on your link), Luhman 16 [wikipedia.org] is the 3rd closest system (6.5 ly), discovered just in 2010 (announced in 2013). WISE 0855−0714 [wikipedia.org] is a sub-brown dwarf (rogue planet) and the 4th closest system (7.3 ly). Finally there is WISE 1506+7027 [wikipedia.org] and WISE 0350−5658 [wikipedia.org] as well as some brown dwarfs orbiting normal stars.
Brown dwarfs can have protoplanetary disks. Maybe even life in a subsurface ocean on a planet/moon orbiting it.
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