Searching for Planet Nine with Coadded WISE and NEOWISE-Reactivation Images

Journal Article · Wed Jan 11 00:00:00 EST 2017 · The Astronomical Journal (Online)

DOI:https://doi.org/10.3847/1538-3881/153/2/65· OSTI ID:1379711

Meisner, Aaron M. ^[1]; Bromley, Benjamin C.  ^[2]; Nugent, Peter E.  ^[3]; Schlegel, David J.  ^[4]; Kenyon, Scott J.  ^[5]; Schlafly, Edward F.  ^[4]; Dawson, Kyle S.  ^[2]

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1. Berkeley Center for Cosmological Physics, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2. Univ. of Utah, Salt Lake City, UT (United States)
3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
5. Smithsonian Astrophysical Observatory, Cambridge, MA (United States)

A distant, as yet unseen ninth planet has been invoked to explain various observations of the outer solar system. While such a "Planet Nine," if it exists, is most likely to be discovered via reflected light in the optical, it may emit much more strongly at 3-5 μm than simple blackbody predictions would suggest, depending on its atmospheric properties. As a result, Planet Nine may be detectable at 3.4 μm with the Wide-field Infrared Survey Explorer, but single exposures are too shallow except at relatively small distances ($${d}_{9}\lesssim 430$$ au). In this paper, we develop a method to search for Planet Nine far beyond the W1 single-exposure sensitivity, to distances as large as 800 au, using inertial coadds of W1 exposures binned into ~1 day intervals. We apply our methodology to a ~2000 square degree testbed sky region which overlaps a southern segment of Planet Nine's anticipated orbital path. We do not detect a plausible Planet Nine candidate, but are able to derive a detailed completeness curve, ruling out its presence within the parameter space searched at W1 < 16.66 (90% completeness). Our method uses all publicly available W1 imaging, spanning 2010 January to 2015 December, and will become more sensitive with future NEOWISE-Reactivation releases of additional W1 exposures. Finally, we anticipate that our method will be applicable to the entire high Galactic latitude sky, and we will extend our search to that full footprint in the near future.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1379711
• Journal Information: The Astronomical Journal (Online), Vol. 153, Issue 2; ISSN 1538-3881
• Publisher: IOP Publishing - AAAS
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
detection of planets and satellites
image processing techniques