Keck Nirspec Radial Velocity Observations of Late-M Dwarfs

Tanner, Angelle; White, R. J.; Bailey, John I.; Blake, Cullen H.; Blake, G. A.; Cruz, Kelle L.; Burgasser, Adam J.; Kraus, Adam L.

doi:10.1088/0067-0049/203/1/10

Cited by 21 publications

(30 citation statements)

References 42 publications

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“…However, this interpretation would predict a density of 38 ρ based on the Baraffe et al (2015) models, which is much lower than the measured density from transit observations (see below). We can also rule out contamination from a stellar or substellar companion based on previous adaptive optics surveys (Siegler et al 2003;Bouy et al 2003;Gizis et al 2003;Janson et al 2012) and multi-epoch radial velocity surveys (Tanner et al 2012;Barnes et al 2014).…”

Section: Age Constraints From the Hr Diagrammentioning

confidence: 99%

On the Age of the TRAPPIST-1 System

Burgasser

Mamajek

2017

ApJ

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115

107

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The nearby (d = 12 pc) M8 dwarf star TRAPPIST-1 (2MASS J23062928−0502285) hosts a compact system of at least seven exoplanets with sizes similar to Earth. Given its importance for testing planet formation and evolution theories, and for assessing the prospects for habitability among Earth-size exoplanets orbiting the most common type of star in the Galaxy, we present a comprehensive assessment of the age of this system. We collate empirical age constraints based on the color-absolute magnitude diagram, average density, lithium absorption, surface gravity features, metallicity, kinematics, rotation, and magnetic activity; and conclude that TRAPPIST-1 is a transitional thin/thick disk star with an age of 7.6±2.2 Gyr. The star's colormagnitude position is consistent with it being slightly metal-rich ([Fe/H] +0.06), in line with its previously reported near-infrared spectroscopic metallicity; and it has a radius (R = 0.121±0.003 R ) that is larger by 8-14% compared to solar-metallicity evolutionary models. We discuss some implications of the old age of this system with regard to the stability and habitability of its planets.

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Section: Age Constraints From the Hr Diagrammentioning

confidence: 99%

On the Age of the TRAPPIST-1 System

Burgasser

Mamajek

2017

ApJ

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115

107

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“…We have also performed a more involved analysis of the companion masses ruled out by the Tanner et al (2012) Doppler RV observations. To assess the detectability of RV companions, we followed the procedure described in Kohn et al (2016).…”

Section: Doppler Constraintsmentioning

confidence: 99%

Astrometric Constraints on the Masses of Long-period Gas Giant Planets in the TRAPPIST-1 Planetary System

Boss

Weinberger

Keiser

et al. 2017

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Transit photometry of the M8V dwarf star TRAPPIST-1 (2MASS J23062928-0502285) has revealed the presence of at least seven planets with masses and radii similar to that of Earth orbiting at distances that might allow liquid water to be present on their surfaces. We have been following TRAPPIST-1 since 2011 with the CAPSCam astrometric camera on the 2.5-m du Pont telescope at the Las Campanas Observatory in Chile. In 2016 we noted that TRAPPIST-1 lies slightly farther away than previously thought, at 12.49 pc, rather than 12.1 pc. Here we examine fifteen epochs of CAPSCam observations of TRAPPIST-1, spanning the five years from 2011 to 2016, and obtain a revised trigonometric distance of 12.56 ± 0.12 pc. The astrometric data analysis pipeline shows no evidence for a long-period astrometric wobble of TRAPPIST-1. After proper motion and parallax are removed, residuals at the level of ±1.3 millarcsec (mas) remain. The amplitude of these residuals constrains the masses of any long-period gas giant planets in the TRAPPIST-1 system: no planet more massive than ∼ 4.6M Jup orbits with a 1 yr period, and no planet more massive than ∼ 1.6M Jup orbits with a 5 yr period. Further refinement of the CAPSCam data analysis pipeline, combined with continued CAPSCam observations, should either detect any longperiod planets, or put an even tighter constraint on these mass upper limits.

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“…As of March 2015, 43 sources in our sample had RV measurements reported in the literature with precisions σ RV ≤ 3 km s −1 Mohanty & Basri 2003;Reiners & Basri 2009;Blake et al 2010;Gálvez-Ortiz et al 2010;Seifahrt et al 2010;Tanner et al 2012); these values are listed in Table 1. We made use of these prior measurements in our RV measurement analysis (Section 3.3).…”

Section: Samplementioning

confidence: 99%

THE BROWN DWARF KINEMATICS PROJECT (BDKP). IV. RADIAL VELOCITIES OF 85 LATE-M AND L DWARFS WITH MagE

Burgasser¹,

Logsdon²,

Gagné³

et al. 2015

ApJS

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Radial velocity measurements are presented for 85 late M-and L-type very low mass stars and brown dwarfs obtained with the Magellan Echellette (MagE) spectrograph. Targets primarily have distances within 20 pc of the Sun, with more distant sources selected for their unusual spectral energy distributions. We achieved precisions of 2-3,km s −1 , and combined these with astrometric and spectrophotometric data to calculate U V W velocities. Most are members of the thin disk of the Galaxy, and velocity dispersions indicate a mean age of 5.2±0.2 Gyr for sources within 20 pc. We find signficantly different kinematic ages between late-M dwarfs (4.0±0.2 Gyr) and L dwarfs (6.5±0.4 Gyr) in our sample that are contrary to predictions from prior simulations. This difference appears to be driven by a dispersed population of unusually -2blue L dwarfs which may be more prevalent in our local volume-limited sample than in deeper magnitude-limited surveys. The L dwarfs exhibit an asymmetric U velocity distribution with a net inward flow, similar to gradients recently detected in local stellar samples. Simulations incorporating brown dwarf evolution and Galactic orbital dynamics are unable to reproduce the velocity asymmetry, suggesting non-axisymmetric perturbations or two distinct L dwarf populations. We also find the L dwarfs to have a kinematic age-activity correlation similar to more massive stars. We identify several sources with low surface gravities, and two new substellar candidate members of nearby young moving groups: the astrometric binary DENIS J08230313−4912012AB, a lowprobability member of the β Pictoris Moving Group; and 2MASS J15104786-2818174, a moderate-probability member of the 30-50 Myr Argus Association.All sources were observed with the MagE spectrograph, mounted on the Magellan 6.5m Landon Clay Telescope at Las Campanas Observatory. A complete observing log is given in Table 2. Data were obtained in 15 nights over a 2.5-year period (November 2008 through March 2011) in a variety of seeing and weather conditions. We used the 0. ′′ 7 slit aligned with the parallactic angle, providing 3200-10050Å spectroscopy at an average resolution λ/∆λ ≈ 4100 (∆RV = 73 km s −1 ) and dispersion of ∼0.5Å pixel −1 at 6000Å. Exposure times varied according to source brightness and weather conditions, and ranged from 150-3600 s. Most sources were observed in a single exposure, although a handful were observed in multiple exposures or over multiple nights to improve data quality. In addition to the target, we obtained nightly observations of spectrophotometric standards from Hamuy et al. (1994) for flux calibration. ThAr lamps were observed after each source observation for wavelength calibration, and internal quartz and dome flat field lamps were obtained 2 Source identifications in the text are given in shorthand notation based on the sexigesimal right ascension and declination, Jhhmm±ddmm. Full source names and coordinates are listed in Table 1.

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Keck Nirspec Radial Velocity Observations of Late-M Dwarfs

Cited by 21 publications

References 42 publications

On the Age of the TRAPPIST-1 System

On the Age of the TRAPPIST-1 System

Astrometric Constraints on the Masses of Long-period Gas Giant Planets in the TRAPPIST-1 Planetary System

THE BROWN DWARF KINEMATICS PROJECT (BDKP). IV. RADIAL VELOCITIES OF 85 LATE-M AND L DWARFS WITH MagE

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