MOA-2011-BLG-293 Lb

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MOA-2011-BLG-293 Lb

Post by Edasich on 6th January 2012, 10:26 am

MOA-2011-BLG-293Lb: A testbed for pure survey microlensing planet detections

Microlensing planet searches are transitioning from "survey+followup" mode to "pure survey" mode, wherein events will be monitored without reference to the presence of planets, which will enable a more rigorous statistical interpretation. Such surveys will be able to monitor many more events but at a lower cadence than typical followup observations, meaning that the significance of the planets detected in this manner will be lower. It would be useful to test these pure survey detections to ensure that even with sparser data, the planets can be reliably detected. MOA-2011-BLG-293 provides one such test. This planet is robustly detected in survey+followup data (DeltaChi^2~5400). The planet/host mass ratio is q=5.1 +/- 0.2*10^(-3). The best fit projected separation is s=0.545 +/- 0.005 Einstein radii. However, due to the s -> 1/s degeneracy, projected separations of 1/s are only marginally disfavored at DeltaChi^2=2. A Bayesian estimate of the host mass gives M_L = 0.44^{+0.27}_{-0.17} M_Sun, with a sharp upper limit of M_L < 1.2 M_Sun from upper limits on the lens flux. Hence, the best estimate of the planet mass is m_p=2.4^{+1.4}_{-0.9} M_Jup, and the physical projected separation is either r_perp ~ 1.0 AU or r_perp ~ 3.5 AU. We show that survey data alone correctly predict this solution and are able to characterize the planet even though the signal from the planet is close to the limit of detectability (DeltaChi^2~500). Analyzing a large sample of events like MOA-2011-BLG-293, which have both followup data and high cadence survey data, will provide a guide for the interpretation of pure survey microlensing data.
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Re: MOA-2011-BLG-293 Lb

Post by Edasich on 23rd January 2012, 9:41 am

Hey, I realized EPE is not listing this new microlensing planet!
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Re: MOA-2011-BLG-293 Lb

Post by Stalker on 23rd January 2012, 10:48 am

http://exoplanet.eu/planet.php?p1=MOA-2011-BLG-293L&p2=b

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Re: MOA-2011-BLG-293 Lb

Post by Edasich on 23rd January 2012, 5:56 pm

Stalker wrote:http://exoplanet.eu/planet.php?p1=MOA-2011-BLG-293L&p2=b

Oh, finally. Very Happy
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Re: MOA-2011-BLG-293 Lb

Post by Sirius_Alpha on 14th October 2013, 10:05 pm

MOA-2011-BLG-293Lb: First Microlensing Planet possibly in the Habitable Zone
http://arxiv.org/abs/1310.3706

We used Keck adaptive optics observations to identify the first planet discovered by microlensing to lie in or near the habitable zone, i.e., at projected separation $r_\perp=1.1\pm 0.1\,$AU from its $M_{L}=0.86\pm 0.06\,M_\odot$ host, being the highest microlensing mass definitely identified. The planet has a mass $m_p = 4.8\pm 0.3\,M_{\rm Jup}$, and could in principle have habitable moons. This is also the first planet to be identified as being in the Galactic bulge with good confidence: $D_L=7.7\pm 0.44$ kpc. The planet/host masses and distance were previously not known, but only estimated using Bayesian priors based on a Galactic model (Yee et al. 2012). These estimates had suggested that the planet might be a super-Jupiter orbiting an M dwarf, a very rare class of planets. We obtained high-resolution $JHK$ images using Keck adaptive optics to detect the lens and so test this hypothesis. We clearly detect light from a G dwarf at the position of the event, and exclude all interpretations other than that this is the lens with high confidence (95%), using a new astrometric technique. The calibrated magnitude of the planet host star is $H_{L}=19.16\pm 0.13$. We infer the following probabilities for the three possible orbital configurations of the gas giant planet: 53% to be in the habitable zone, 35% to be near the habitable zone, and 12% to be beyond the snow line, depending on the atmospherical conditions.

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Re: MOA-2011-BLG-293 Lb

Post by Edasich on 15th October 2013, 3:29 am

So it is confirmed with updated orbital parameters. With L=ca. 0.43 Lsun the planet would actually lay within Mars' orbital zone.
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