THE ROTATION AND GALACTIC KINEMATICS OF MID M DWARFS IN THE SOLAR NEIGHBORHOOD

By E. Newton, J. Irwin, D. Charbonneau, Z. Berta-Thompson, J. Dittmann, Andrew A. West. 2015

145 citations recorded by the source corpus.

Rotation is a directly observable stellar property, and it drives magnetic field generation and activity through a magnetic dynamo. Main-sequence stars with masses below approximately 0.35 M ⊙ (mid-to-late M dwarfs) are fully convective, and are expected to have a different type of dynamo mechanism than solar-type stars. Measurements of their rotation rates provide insight into these mechanisms, but few rotation periods are available for these stars at field ages. Using photometry from the MEarth Project, we measure rotation periods for 387 nearby, mid-to-late M dwarfs in the northern hemisphere, finding periods from 0.1 to 140 days. The typical rotator has stable, sinusoidal photometric modulations at a semi-amplitude of 0.5%–1%. We find no period–amplitude relation for stars below 0.25 M ⊙ and an anticorrelation between period and amplitude for higher-mass M dwarfs. We highlight the existence of older, slowly rotating stars without Hα emission that nevertheless have strong photometric variability. We use parallaxes, proper motions, radial velocities, photometry, and near-infrared metallicity estimates to further characterize the population of rotators. The Galactic kinematics of our sample is consistent with the local population of G and K dwarfs, and rotators have metallicities characteristic of the solar neighborhood. We use the W space velocities and established age–velocity relations to estimate that stars with P < 10 days have ages of on average <2 Gyr, and that those with P > 70 days have ages of about 5 Gyr. The period distribution is dependent on mass: as the mass decreases, the slowest rotators at a given mass have longer periods, and the fastest rotators have shorter periods. We find a lack of stars with intermediate rotation periods, and the gap between the fast and slow rotators is larger for lower masses. Our data are consistent with a scenario in which these stars maintain rapid rotation for several gigayears, then spin down quickly, reaching periods of around 100 days by a typical age of 5 Gyr.

Subfields: Astronomy and Astrophysics, Instrumentation, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/c5f106dd1dfa7303cedde1b1b733c9d603fd0094

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. D. Charbonneau
2. E. Gaidos
3. J. Johnson
4. A. Mann
5. Sara Seager
6. Jon Fortney
7. J. Southworth
8. J. Winn

In Instrumentation

1. D. Charbonneau
2. E. Gaidos
3. A. Mann
4. J. Winn
5. J. Southworth
6. J. Johnson
7. Sara Seager
8. J. Owen

In Molecular Biology

1. J. Winn
2. J. Johnson
3. Aomawa L. Shields
4. S. Ballard
5. R. Yadav

Citations in the corpus

• Water loss from terrestrial planets orbiting ultracool dwarfs: implications for the planets of TRAPPIST-1 (2016, background): “…Its bolometric luminosity Lbol/L ∼ 10−3.29 is close to the luminosity of TRAPPIST-1 (Lbol/L ∼ 10−3.28), its V sin i of 8 km.s−1(Reid et al. 2002; Newton et al. 2016) is also close to TRAPPIST-1’s ∼ 6 km.s−1. recently for TRAPPIST-1 LX/Lbol = 10−3.7 to 10−3.4, which is significantly…”
• ZODIACAL EXOPLANETS IN TIME (ZEIT). III. A SHORT-PERIOD PLANET ORBITING A PRE-MAIN-SEQUENCE STAR IN THE UPPER SCORPIUS OB ASSOCIATION (2016, background): “While spot patterns can be stable on multi-year baseline in old M dwarfs (Newton et al. 2016), spot evolution can been seen even over the 80 day observing window for Upper Scorpius members (e.g., Figure 1, 9).”
• The Habitability of Planets Orbiting M-dwarf Stars (2016, background): “However, below the convective limit there appear two divergent populations of faster and slower rotators (Irwin et al., 2011; Newton et al., 2016b).”
• Characterization of the K2-18 multi-planetary system with HARPS: A habitable zone super-Earth and discovery of a second, warm super-Earth on a non-coplanar orbit (2017, background): “This makes K2-18 a moderately active early M dwarf in terms of its photometric variability (Newton et al. 2016) the origin of which likely results from the rotation of active regions across the projected stellar disk at or close to Prot owing to the characteristically low amplitudes of differential…”
• Stellar Flares from the First TESS Data Release: Exploring a New Sample of M Dwarfs (2019, background): “This is particularly a problem for habitable-zone planets around field-aged early M dwarfs (Newton et al. 2016; Vanderburg et al. 2016).”
• The stellar rotation–activity relationship in fully convective M dwarfs (2018, methodology): “21 targets were chosen from the MEarth sample that had rotation periods measured by Irwin et al. (2011) and Newton et al. (2016, 2018).”
• THE Hα EMISSION OF NEARBY M DWARFS AND ITS RELATION TO STELLAR ROTATION (2016, methodology): “Our observations often span 6 months or longer, providing excellent sensitivity to long periods (Irwin et al. 2011; Newton et al. 2016).”