CHARACTERIZING THE COOL KOIs. III. KOI 961: A SMALL STAR WITH LARGE PROPER MOTION AND THREE SMALL PLANETS
We characterize the star KOI 961, an M dwarf with transit signals indicative of three short-period exoplanets discovered by the Kepler mission. We proceed by comparing KOI 961 to Barnard's Star, a nearby, well-characterized mid-M dwarf. We compare colors, optical and near-infrared spectra, and...
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IOP Publishing
2015
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| Online Access: | http://hdl.handle.net/1721.1/95465 |
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| author | Muirhead, Philip S. Johnson, John Asher Apps, Kevin Carter, Joshua Adam Morton, Timothy D. Fabrycky, Daniel C. Pineda, John Sebastian Bottom, Michael Schlawin, Everett Hamren, Katherine Covey, Kevin R. Crepp, Justin R. Pepper, Joshua Hebb, Leslie Kirby, Evan N. Howard, Andrew W. Isaacson, Howard Marcy, Geoffrey W. Levitan, David Diaz-Santos, Tanio Armus, Lee Lloyd, James P. Stassun, Keivan Rojas-Ayala, Barbara |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Muirhead, Philip S. Johnson, John Asher Apps, Kevin Carter, Joshua Adam Morton, Timothy D. Fabrycky, Daniel C. Pineda, John Sebastian Bottom, Michael Schlawin, Everett Hamren, Katherine Covey, Kevin R. Crepp, Justin R. Pepper, Joshua Hebb, Leslie Kirby, Evan N. Howard, Andrew W. Isaacson, Howard Marcy, Geoffrey W. Levitan, David Diaz-Santos, Tanio Armus, Lee Lloyd, James P. Stassun, Keivan Rojas-Ayala, Barbara |
| author_sort | Muirhead, Philip S. |
| collection | MIT |
| description | We characterize the star KOI 961, an M dwarf with transit signals indicative of three short-period exoplanets discovered by the Kepler mission. We proceed by comparing KOI 961 to Barnard's Star, a nearby, well-characterized mid-M dwarf. We compare colors, optical and near-infrared spectra, and find remarkable agreement between the two, implying similar effective temperatures and metallicities. Both are metal-poor compared to the Solar neighborhood, have low projected rotational velocity, high absolute radial velocity, large proper motion, and no quiescent Hα emission—all of which are consistent with being old M dwarfs. We combine empirical measurements of Barnard's Star and expectations from evolutionary isochrones to estimate KOI 961's mass (0.13 ± 0.05 M [subscript ☉]), radius (0.17 ± 0.04 R [subscript ☉]), and luminosity (2.40 × 10[superscript –3.0 ± 0.3] L [subscript ☉]). We calculate KOI 961's distance (38.7 ± 6.3 pc) and space motions, which, like Barnard's Star, are consistent with a high scale-height population in the Milky Way. We perform an independent multi-transit fit to the public Kepler light curve and significantly revise the transit parameters for the three planets. We calculate the false-positive probability for each planet candidate, and find a less than 1% chance that any one of the transiting signals is due to a background or hierarchical eclipsing binary, validating the planetary nature of the transits. The best-fitting radii for all three planets are less than 1 R [subscript ⊕], with KOI 961.03 being Mars-sized (R[subscript P] = 0.57 ± 0.18 R [subscript ⊕]), and they represent some of the smallest exoplanets detected to date. |
| first_indexed | 2024-09-23T15:09:22Z |
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| id | mit-1721.1/95465 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T15:09:22Z |
| publishDate | 2015 |
| publisher | IOP Publishing |
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| spelling | mit-1721.1/954652022-09-29T13:02:05Z CHARACTERIZING THE COOL KOIs. III. KOI 961: A SMALL STAR WITH LARGE PROPER MOTION AND THREE SMALL PLANETS Muirhead, Philip S. Johnson, John Asher Apps, Kevin Carter, Joshua Adam Morton, Timothy D. Fabrycky, Daniel C. Pineda, John Sebastian Bottom, Michael Schlawin, Everett Hamren, Katherine Covey, Kevin R. Crepp, Justin R. Pepper, Joshua Hebb, Leslie Kirby, Evan N. Howard, Andrew W. Isaacson, Howard Marcy, Geoffrey W. Levitan, David Diaz-Santos, Tanio Armus, Lee Lloyd, James P. Stassun, Keivan Rojas-Ayala, Barbara Massachusetts Institute of Technology. Department of Physics Stassun, Keivan We characterize the star KOI 961, an M dwarf with transit signals indicative of three short-period exoplanets discovered by the Kepler mission. We proceed by comparing KOI 961 to Barnard's Star, a nearby, well-characterized mid-M dwarf. We compare colors, optical and near-infrared spectra, and find remarkable agreement between the two, implying similar effective temperatures and metallicities. Both are metal-poor compared to the Solar neighborhood, have low projected rotational velocity, high absolute radial velocity, large proper motion, and no quiescent Hα emission—all of which are consistent with being old M dwarfs. We combine empirical measurements of Barnard's Star and expectations from evolutionary isochrones to estimate KOI 961's mass (0.13 ± 0.05 M [subscript ☉]), radius (0.17 ± 0.04 R [subscript ☉]), and luminosity (2.40 × 10[superscript –3.0 ± 0.3] L [subscript ☉]). We calculate KOI 961's distance (38.7 ± 6.3 pc) and space motions, which, like Barnard's Star, are consistent with a high scale-height population in the Milky Way. We perform an independent multi-transit fit to the public Kepler light curve and significantly revise the transit parameters for the three planets. We calculate the false-positive probability for each planet candidate, and find a less than 1% chance that any one of the transiting signals is due to a background or hierarchical eclipsing binary, validating the planetary nature of the transits. The best-fitting radii for all three planets are less than 1 R [subscript ⊕], with KOI 961.03 being Mars-sized (R[subscript P] = 0.57 ± 0.18 R [subscript ⊕]), and they represent some of the smallest exoplanets detected to date. Vanderbilt University (Initiative in Data-Intensive Astrophysics) National Science Foundation (U.S.) (Grant AST-0849736) National Science Foundation (U.S.) (Grant AST-1009810) 2015-02-20T19:20:47Z 2015-02-20T19:20:47Z 2012-02 2011-12 Article http://purl.org/eprint/type/JournalArticle 0004-637X 1538-4357 http://hdl.handle.net/1721.1/95465 Muirhead, Philip S., John Asher Johnson, Kevin Apps, Joshua A. Carter, Timothy D. Morton, Daniel C. Fabrycky, John Sebastian Pineda, et al. “CHARACTERIZING THE COOL KOIs. III. KOI 961: A SMALL STAR WITH LARGE PROPER MOTION AND THREE SMALL PLANETS.” The Astrophysical Journal 747, no. 2 (February 24, 2012): 144. © 2012 The American Astronomical Society en_US http://dx.doi.org/10.1088/0004-637x/747/2/144 The Astrophysical Journal Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf IOP Publishing American Astronomical Society |
| spellingShingle | Muirhead, Philip S. Johnson, John Asher Apps, Kevin Carter, Joshua Adam Morton, Timothy D. Fabrycky, Daniel C. Pineda, John Sebastian Bottom, Michael Schlawin, Everett Hamren, Katherine Covey, Kevin R. Crepp, Justin R. Pepper, Joshua Hebb, Leslie Kirby, Evan N. Howard, Andrew W. Isaacson, Howard Marcy, Geoffrey W. Levitan, David Diaz-Santos, Tanio Armus, Lee Lloyd, James P. Stassun, Keivan Rojas-Ayala, Barbara CHARACTERIZING THE COOL KOIs. III. KOI 961: A SMALL STAR WITH LARGE PROPER MOTION AND THREE SMALL PLANETS |
| title | CHARACTERIZING THE COOL KOIs. III. KOI 961: A SMALL STAR WITH LARGE PROPER MOTION AND THREE SMALL PLANETS |
| title_full | CHARACTERIZING THE COOL KOIs. III. KOI 961: A SMALL STAR WITH LARGE PROPER MOTION AND THREE SMALL PLANETS |
| title_fullStr | CHARACTERIZING THE COOL KOIs. III. KOI 961: A SMALL STAR WITH LARGE PROPER MOTION AND THREE SMALL PLANETS |
| title_full_unstemmed | CHARACTERIZING THE COOL KOIs. III. KOI 961: A SMALL STAR WITH LARGE PROPER MOTION AND THREE SMALL PLANETS |
| title_short | CHARACTERIZING THE COOL KOIs. III. KOI 961: A SMALL STAR WITH LARGE PROPER MOTION AND THREE SMALL PLANETS |
| title_sort | characterizing the cool kois iii koi 961 a small star with large proper motion and three small planets |
| url | http://hdl.handle.net/1721.1/95465 |
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