Title: Astrometric confirmation and preliminary orbital parameters of the young exoplanet 51 Eridani b with the Gemini Planet Imager

Abstract

We present new Gemini Planet Imager observations of the young exoplanet 51 Eridani b that provide further evidence that the companion is physically associated with 51 Eridani. Combining this new astrometric measurement with those reported in the literature, we significantly reduce the posterior probability that 51 Eridani b is an unbound foreground or background T-dwarf in a chance alignment with 51 Eridani to 2 × 10^–7, an order of magnitude lower than previously reported. If 51 Eridani b is indeed a bound object, then we have detected orbital motion of the planet between the discovery epoch and the latest epoch. By implementing a computationally efficient Monte Carlo technique, preliminary constraints are placed on the orbital parameters of the system. The current set of astrometric measurements suggest an orbital semimajor axis of $${14}_{-3}^{+7}$$ AU, corresponding to a period of $${41}_{-12}^{+35}$$ years (assuming a mass of 1.75 M⊙ for the central star), and an inclination of $${138}_{-13}^{+15}$$ deg. The remaining orbital elements are only marginally constrained by the current measurements. As a result, these preliminary values suggest an orbit that does not share the same inclination as the orbit of the distant M-dwarf binary, GJ 3305, which is a wide physically bound companion to 51 Eridani.

Authors:

De Rosa, Robert J. ^[1]; Nielsen, Eric L. ^[2]; Blunt, Sarah C. ^[3]; Graham, James R. ^[1]; Konopacky, Quinn M. ^[4]; Marois, Christian ^[5]; Pueyo, Laurent ^[6]; Rameau, Julien ^[7]; Ryan, Dominic M. ^[1]; Wang, Jason J. ^[1]; Bailey, Vanessa ^[8]; Chontos, Ashley ^[8]; Fabrycky, Daniel C. ^[9]; Follette, Katherine B. ^[8]; Macintosh, Bruce ^[8]; Marchis, Franck ^[10]; Ammons, S. Mark ^[11]; Arriaga, Pauline ^[12]; Chilcote, Jeffrey K. ^[13]; Cotten, Tara H. ^[14] more »; Doyon, René ^[7]; Duchêne, Gaspard ^[15]; Esposito, Thomas M. ^[1]; Fitzgerald, Michael P. ^[12]; Gerard, Benjamin ^[16]; Goodsell, Stephen J. ^[17]; Greenbaum, Alexandra Z. ^[18]; Hibon, Pascale ^[19]; Ingraham, Patrick ^[20]; Johnson-Groh, Mara ^[16]; Kalas, Paul G. ^[1]; Lafrenière, David ^[7]; Maire, Jerome ^[13]; Metchev, Stanimir ^[21]; Millar-Blanchaer, Maxwell A. ^[13]; Morzinski, Katie M. ^[22]; Oppenheimer, Rebecca ^[23]; Patel, Rahul I. ^[24]; Patience, Jennifer L. ^[25]; Perrin, Marshall D. ^[6]; Rajan, Abhijith ^[25]; Rantakyrö, Fredrik T. ^[19]; Ruffio, Jean-Baptiste ^[8]; Schneider, Adam C. ^[26]; Sivaramakrishnan, Anand ^[6]; Song, Inseok ^[14]; Tran, Debby ^[4]; Vasisht, Gautam ^[27]; Ward-Duong, Kimberly ^[25]; Wolff, Schuyler G. ^[18] « less

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+ Show Author Affiliations

1. Univ. of California, Berkeley, CA (United States)
2. SETI Institute, Mountain View, CA (United States); Stanford Univ., Stanford, CA (United States)
3. SETI Institute, Mountain View, CA (United States); Brown Univ., Providence, RI (United States)
4. Univ. of California, San Diego, La Jolla, CA (United States)
5. National Research Council of Canada Herzberg, Victoria, BC (Canada); Univ. of Victoria, Victoria, BC (Canada)
6. Space Telescope Science Institute, Baltimore, MD (United States)
7. Univ. de Montreal, Montreal, QC (Canada)
8. Stanford Univ., Stanford, CA (United States)
9. Univ. of Chicago, Chicago, IL (United States)
10. SETI Institute, Mountain View, CA (United States)
11. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
12. Univ. of California, Los Angeles, CA (United States)
13. Univ. of Toronto, Toronto, ON (Canada)
14. Univ. of Georgia, Athens, GA (United States)
15. Univ. of California, Berkeley, CA (United States); Univ. Grenoble Alpes/CNRS, Grenoble (France)
16. Univ. of Victoria, Victoria, BC (Canada)
17. Durham Univ., Durham (United Kingdom); Gemini Observatory, La Serena (Chile)
18. Johns Hopkins Univ., Baltimore, MD (United States)
19. Gemini Observatory, Hilo, HI (United States)
20. Large Synoptic Survey Telescope, Tucson, AZ (United States)
21. The Univ. of Western Ontario, London, ON (Canada); Stony Brook Univ., Stony Brook, NY (United States)
22. Univ. of Arizona, Tucson, AZ (United States)
23. American Museum of Natural History, New York, NY (United States)
24. Stony Brook Univ., Stony Brook, NY (United States)
25. Arizona State Univ., Tempe, AZ (United States)
26. Univ. of Toledo, Toledo, OH (United States)
27. California Inst. of Technology (CalTech), Pasadena, CA (United States)

Publication Date:

Fri Nov 13 00:00:00 EST 2015

Research Org.:

Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1324508

Report Number(s):

LLNL-JRNL-678574
Journal ID: ISSN 2041-8213

Grant/Contract Number:  

AC52-07NA27344

Resource Type:

Accepted Manuscript

Journal Name:

The Astrophysical Journal. Letters (Online)

Additional Journal Information:

Journal Name: The Astrophysical Journal. Letters (Online); Journal Volume: 814; Journal Issue: 1; Journal ID: ISSN 2041-8213

Publisher:

Institute of Physics (IOP)

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; planetary systems; planets and satellites: detection; stars: individual (51 Eri)