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DOI10.3847/1538-3881/aad775
exocartographer: A Bayesian Framework for Mapping Exoplanets in Reflected Light
Farr, Ben1,2; Farr, Will M.3,4,5; Cowan, Nicolas B.6,7; Haggard, Hal M.8,9; Robinson, Tyler10
通讯作者Farr, Ben
来源期刊ASTRONOMICAL JOURNAL
ISSN0004-6256
EISSN1538-3881
出版年2018
卷号156期号:4
英文摘要

Future space telescopes will directly image extrasolar planets at visible wavelengths. Time-resolved reflected light from an exoplanet encodes information about atmospheric and surface inhomogeneities. Previous research has shown that the light curve of an exoplanet can be inverted to obtain a low-resolution map of the planet, as well as constraints on its spin orientation. Estimating the uncertainty on 2D albedo maps has so far remained elusive. Here, we present exocartographer, a flexible open-source Bayesian framework for solving the exocartography inverse problem. The map is parameterized with equal-area Hierarchical, Equal Area, and isoLatitude Pixelation (HEALPix) pixels. For a fiducial map resolution of 192 pixels, a four-parameter Gaussian process describing the spatial scale of albedo variations, and two unknown planetary spin parameters, exocartographer explores a 198-dimensional parameter space. To test the code, we produce a light curve for a cloudless Earth in a face-on orbit with a 90 degrees obliquity. We produce synthetic white-light observations of the planet: five epochs of observations throughout the planet’s orbit, each consisting of 24 hourly observations with a photometric uncertainty of 1% (120 data points). We retrieve an albedo map and-for the first time-its uncertainties, along with spin constraints. The albedo map is recognizably of Earth, with a typical 90% uncertainty of 0.14. The retrieved characteristic length scale is similar to 9800 km. The obliquity is recovered to be >87 degrees.9 at the 90% credible level. Despite the uncertainty in the retrieved albedo map, we robustly identify a high-albedo region (the Sahara desert) and a large low-albedo region (the Pacific Ocean).


英文关键词methods: data analysis planetary systems
类型Article
语种英语
国家USA ; England ; Canada
收录类别SCI-E
WOS记录号WOS:000444427400004
WOS关键词EXTRASOLAR TERRESTRIAL PLANETS ; EARTH-LIKE EXOPLANETS ; CURVES ; OBLIQUITY ; OCEAN ; STARS
WOS类目Astronomy & Astrophysics
WOS研究方向Astronomy & Astrophysics
资源类型期刊论文
条目标识符http://119.78.100.177/qdio/handle/2XILL650/207842
作者单位1.Univ Oregon, Dept Phys, Eugene, OR 97403 USA;
2.Univ Chicago, Enrico Fermi Inst, 5640 S Ellis Ave, Chicago, IL 60637 USA;
3.Univ Birmingham, Sch Phys & Astron, Birmingham Inst Gravitat Wave Astron, Birmingham B15 2TT, W Midlands, England;
4.SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA;
5.Flatiron Inst, Ctr Computat Astrophys, 162 Fifth Ave, New York, NY 10010 USA;
6.McGill Univ, Dept Phys, 3550 Rue Univ, Montreal, PQ H3A 2A7, Canada;
7.McGill Univ, Dept Earth & Planetary Sci, 3550 Rue Univ, Montreal, PQ H3A 2A7, Canada;
8.Bard Coll, Phys Program, 30 Campus Rd, Annondale On Hudson, NY 12504 USA;
9.Perimeter Inst Theoret Phys, 31 Caroline St North, Waterloo, ON N2L 2Y5, Canada;
10.No Arizona Univ, Dept Phys & Astron, Flagstaff, AZ 86011 USA
推荐引用方式
GB/T 7714
Farr, Ben,Farr, Will M.,Cowan, Nicolas B.,et al. exocartographer: A Bayesian Framework for Mapping Exoplanets in Reflected Light[J],2018,156(4).
APA Farr, Ben,Farr, Will M.,Cowan, Nicolas B.,Haggard, Hal M.,&Robinson, Tyler.(2018).exocartographer: A Bayesian Framework for Mapping Exoplanets in Reflected Light.ASTRONOMICAL JOURNAL,156(4).
MLA Farr, Ben,et al."exocartographer: A Bayesian Framework for Mapping Exoplanets in Reflected Light".ASTRONOMICAL JOURNAL 156.4(2018).
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