Examinando por Autor "Matthews, Elisabeth"

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    A Super-Earth and Sub-Neptune Transiting the Late-type M Dwarf LP 791-18
    (Astrophysical Journal Letters, 2019-09-20) Crossfield, Ian J. M.; Waalkes, William; Newton, Elisabeth R.; Narita, Norio; Muirhead, Philip; Ment, Kristo; Matthews, Elisabeth; Kraus, Adam; Kostov, Veselin
    Planets occur most frequently around cool dwarfs, but only a handful of specific examples are known to orbit the latest-type M stars. Using TESS photometry, we report the discovery of two planets transiting the low-mass star called LP 791-18 (identified by TESS as TOI 736). This star has spectral type M6V, effective temperature 2960 K, and radius 0.17 R o, making it the third-coolest star known to host planets. The two planets straddle the radius gap seen for smaller exoplanets; they include a 1.1R ⊕ planet on a 0.95 day orbit and a 2.3R ⊕ planet on a 5 day orbit. Because the host star is small the decrease in light during these planets' transits is fairly large (0.4% and 1.7%). This has allowed us to detect both planets' transits from ground-based photometry, refining their radii and orbital ephemerides. In the future, radial velocity observations and transmission spectroscopy can both probe these planets' bulk interior and atmospheric compositions, and additional photometric monitoring would be sensitive to even smaller transiting planets.
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    A super-Earth and two sub-Neptunes transiting the nearby and quiet M dwarf TOI-270
    (Nature Research, 2019-12-01) Günther, Maximilian N.; Pozuelos, Francisco J.; Dittmann, Jason A.; Dragomir, Diana; Kane, Stephen R.; Daylan, Tansu; Feinstein, Adina D.; Huang, Chelsea X.; Morton, Timothy D.; Bonfanti, Andrea; Bouma, L. G.; Burt, Jennifer; Collins, Karen A.; Lissauer, Jack J.; Matthews, Elisabeth; Montet, Benjamin T.; Vanderburg, Andrew; Wang, Songhu; Winters, Jennifer G.; Ricker, George R.; Vanderspek, Roland K.; Latham, David W.; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Armstrong, James D.; Barkaoui, Khalid; Batalha, Natalie; Bean, Jacob L.; Caldwell, Douglas A.; Ciardi, David R.; Collins, Kevin I.; Crossfield, Ian; Fausnaugh, Michael; Furesz, Gabor; Gan, Tianjun; Gillon, Michaël; Guerrero, Natalia; Horne, Keith; Howell, Steve B.; Ireland, Michael; Isopi, Giovanni; Jehin, Emmanuël; Kielkopf, John F.; Lepine, Sebastien; Mallia, Franco; Matson, Rachel A.; Myers, Gordon; Palle, Enric; Quinn, Samuel N.; Relles, Howard M.; Rojas-Ayala, Bárbara; Schlieder, Joshua; Sefako, Ramotholo; Shporer, Avi; Suárez, Juan C.; Tan, Thiam-Guan; Ting, Eric B.; Twicken, Joseph D.; Waite, Ian A.
    One of the primary goals of exoplanetary science is to detect small, temperate planets passing (transiting) in front of bright and quiet host stars. This enables the characterization of planetary sizes, orbits, bulk compositions, atmospheres and formation histories. These studies are facilitated by small and cool M dwarf host stars. Here we report the Transiting Exoplanet Survey Satellite (TESS)1 discovery of three small planets transiting one of the nearest and brightest M dwarf hosts observed to date, TOI-270 (TIC 259377017, with K-magnitude 8.3, and 22.5 parsecs away from Earth). The M3V-type star is transited by the super-Earth-sized planet TOI-270 b (1.247−0.083+0.089R⊕) and the sub-Neptune-sized planets TOI-270 c (2.42 ± 0.13 R⊕) and TOI-270 d (2.13 ± 0.12 R⊕). The planets orbit close to a mean-motion resonant chain, with periods (3.36 days, 5.66 days and 11.38 days, respectively) near ratios of small integers (5:3 and 2:1). TOI-270 is a prime target for future studies because (1) its near-resonance allows the detection of transit timing variations, enabling precise mass measurements and dynamical studies; (2) its brightness enables independent radial-velocity mass measurements; (3) the outer planets are ideal for atmospheric characterization via transmission spectroscopy; and (4) the quietness of the star enables future searches for habitable zone planets. Altogether, very few systems with small, temperate exoplanets are as suitable for such complementary and detailed characterization as TOI-270.