Spectroscopic confirmation of M-dwarf candidate members of the Beta Pictoris and AB Doradus Moving Groups

Context. Evolutionary models are widely used to infer the mass of stars, brown dwarfs, and giant planets. Their predictions are thought to be less reliable at young ages (< 200 Myr) and in the low-mass regime (< 1 M⊙). GJ 2060 AB and TWA 22 AB are two rare astrometric M-dwarf binaries, respectively members of the AB Doradus (AB Dor) and Beta Pictoris (β Pic) moving groups. As their dynamical mass can be measured to within a few years, they can be used to calibrate the evolutionary tracks and set new constraints on the age of young moving groups. Aims. We provide the first dynamical mass measurement of GJ 2060 and a refined measurement of the total mass of TWA 22. We also characterize the atmospheric properties of the individual components of GJ 2060 that can be used as inputs to the evolutionary models. Methods. We used NaCo and SPHERE observations at VLT and archival Keck/NIRC2 data to complement the astrometric monitoring of the binaries. We combined the astrometry with new HARPS radial velocities (RVs) and FEROS RVs of GJ 2060. We used a Markov chain Monte-Carlo (MCMC) module to estimate posteriors on the orbital parameters and dynamical masses of GJ 2060 AB and TWA 22 AB from the astrometry and RVs. Complementary data obtained with the integral field spectrograph VLT/SINFONI were gathered to extract the individual near-infrared (1.1–2.5 μm) medium-resolution (R ∼ 1500 − 2000) spectra of GJ 2060 A and B. We compared the spectra to those of known objects and to grids of BT-SETTL model spectra to infer the spectral type, bolometric luminosities, and temperatures of those objects. Results. We find a total mass of 0.18 ± 0.02 M⊙ for TWA 22, which is in good agreement with model predictions at the age of the β Pic moving group. We obtain a total mass of 1.09 ± 0.10 M⊙ for GJ 2060. We estimate a spectral type of M1 ± 0.5, L/L⊙ = −1.20 ± 0.05 dex, and Teff = 3700 ± 100 K for GJ 2060 A. The B component is a M3 ± 0.5 dwarf with L/L⊙ = −1.63 ± 0.05 dex and Teff = 3400 ± 100 K. The dynamical mass of GJ 2060 AB is inconsistent with the most recent models predictions (BCAH15, PARSEC) for an AB Dor age in the range 50–150 Myr. It is 10%–20% (1–2σ, depending on the assumed age) above the model’s predictions, corresponding to an underestimation of 0.10–0.20 M⊙. Coevality suggests a young age for the system (∼50 Myr) according to most evolutionary models. Conclusions. TWA 22 validates the predictions of recent evolutionary tracks at ∼20 Myr. On the other hand, we evidence a 1–2σ mismatch between the predicted and observed mass of GJ 2060 AB. This slight departure may indicate that one of the stars hosts a tight companion. Alternatively, this would confirm the model’s tendency to underestimate the mass of young low-mass stars.

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The Debris Disk Fraction for M-dwarfs in Nearby Young Moving Groups

Proceedings of the International Astronomical Union ◽

10.1017/s1743921315006158 ◽

2015 ◽

Vol 10 (S314) ◽

pp. 159-162 ◽

Cited By ~ 1

Author(s):

Alex Binks

Keyword(s):

Stellar Wind ◽

Rapid Decline ◽

Debris Disks ◽

M Dwarfs ◽

Disk Structure ◽

Debris Disk ◽

The Absolute ◽

Moving Groups ◽

M Dwarf

AbstractI present the first substantial work to measure the fraction of debris disks for M-dwarfs in nearby moving groups (MGs). Utilising the AllWISE IR catalog, 17 out of 151 MG members are found with an IR photometric excess indicative of disk structure. The M-dwarf debris disk fraction is ≲6 per cent in MGs younger than 40 Myr, and none are found in the groups older than 40 Myr. Simulations show, however, that debris disks around M-dwarfs are not present above a WISEW1-W4 colour of ~2.5, making calculating the absolute disk fractions difficult. The debris disk dissipation timescale appears to be faster than for higher-mass stars, and mechanisms such as enhanced stellar wind drag and/or photoevaporation could account for the more rapid decline of disks observed amongst M-dwarfs.

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Where the Wild Young M Dwarfs Are: the SUPERBLINK Proper Motion Survey and a Search for Low-mass Moving Group Candidates

Proceedings of the International Astronomical Union ◽

10.1017/s1743921315006365 ◽

2015 ◽

Vol 10 (S314) ◽

pp. 69-70

Author(s):

Sébastien Lépine

Keyword(s):

Local Field ◽

Proper Motion ◽

Field Population ◽

Velocity Space ◽

Significant Fraction ◽

Proper Motions ◽

M Dwarfs ◽

Low Mass ◽

Moving Groups ◽

M Dwarf

AbstractThe SUPERBLINK survey catalogs all stars brighter than R = 19 mag and with proper motions larger than 40 mas yr−1, down to a declination of −33○. The catalog inevitably includes a significant fraction of the presumed low-mass members of several nearby young moving groups (Beta Pic, AB Dor, Tuc-Hor, Argus), or low-mass escapees from the Hyades and Pleiades clusters. We discuss opportunities and challenges in identifying the missing M dwarf members of these moving groups. While rounding up the majority of the potential M dwarf members of these groups, such samples are significantly affected by co-moving field stars, both young and old, due to the heavy clumping of the local field population in velocity space.

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Characterising young visual M-dwarf binaries with near-infrared integral field spectra

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038030 ◽

2020 ◽

Vol 642 ◽

pp. A57

Author(s):

Per Calissendorff ◽

Markus Janson ◽

Mickaël Bonnefoy

Keyword(s):

Near Infrared ◽

Evolutionary Models ◽

Low Mass Stars ◽

Multiple Systems ◽

Low Mass ◽

Moving Groups ◽

Band Spectra ◽

The Individual ◽

M Dwarf ◽

Integral Field

We present the results from an integral field spectroscopy study of seven close visual binary pairs of young M-dwarf multiple systems. The target systems are part of the astrometric monitoring AstraLux programme, surveying hundreds of M-dwarf systems for multiplicity and obtaining astrometric epochs for orbital constraints. Our new VLT/SINFONI data provides resolved spectral type classifications in the J, H, and K bands for seven of these low-mass M-dwarf binaries, which we determine by comparing them to empirical templates and examining the strength of water absorption in the K band. The medium resolution K-band spectra also allows us to derive effective temperatures for the individual components. All targets in the survey display several signs of youth, and some have kinematics similar to young moving groups, or low surface gravities which we determined from measuring equivalent widths of gravity sensitive alkali lines in the J band. Resolved photometry from our targets is also compared with isochrones from theoretical evolutionary models, further implying young ages. Dynamical masses will be provided from continued monitoring of these systems, which can be seen as emblematic binary benchmarks that may be used to calibrate evolutionary models for low-mass stars in the future.

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Searching for Possible Members of Star Moving Groups in the Kepler Field

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316007067 ◽

2015 ◽

Vol 12 (S316) ◽

pp. 353-354 ◽

Cited By ~ 1

Author(s):

Chang Yao Chen ◽

W. P. Chen ◽

Ali Luo

Keyword(s):

Pilot Study ◽

Radial Velocity ◽

Young Stars ◽

Radial Motion ◽

Velocity Data ◽

X Ray ◽

Beta Pictoris ◽

Group A ◽

Moving Groups ◽

Radial Velocity Data

AbstractWe present identification of candidate members of the Beta Pictoris, AB Doradus, and TW Hydrae moving star groups. Our pilot study toward the Kepler field, where a multitude of stellar parameters are available, led to a list of 19 highly probable candidates that share the same range of distance and space (tangential and radial) motion as known members in a moving group. A few candidates lack radial velocity data, but are ROSAT X-ray sources, so are considered as likely young stars.

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Erratum: Optical and X-ray observations of stellar flares on an active M dwarf AD Leonis with Seimei Telescope, SCAT, NICER, and OISTER

Publications of the Astronomical Society of Japan ◽

10.1093/pasj/psab013 ◽

2021 ◽

Author(s):

Kosuke Namekata ◽

Hiroyuki Maehara ◽

Ryo Sasaki ◽

Hiroki Kawai ◽

Yuta Notsu ◽

...

Keyword(s):

X Ray ◽

Stellar Flares ◽

M Dwarf

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Birth sites of young stellar associations and recent star formation in a flocculent corrugated disc

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3189 ◽

2020 ◽

Vol 499 (4) ◽

pp. 5623-5640

Author(s):

Alice C Quillen ◽

Alex R Pettitt ◽

Sukanya Chakrabarti ◽

Yifan Zhang ◽

Jonathan Gagné ◽

...

Keyword(s):

Space Distribution ◽

Solar Neighbourhood ◽

Low Velocity ◽

Stellar Association ◽

Stellar Orbits ◽

Pattern Speeds ◽

Moving Groups ◽

Orbit Integration ◽

Stellar Associations ◽

Spiral Arm

ABSTRACT With backwards orbit integration, we estimate birth locations of young stellar associations and moving groups identified in the solar neighbourhood that are younger than 70 Myr. The birth locations of most of these stellar associations are at a smaller galactocentric radius than the Sun, implying that their stars moved radially outwards after birth. Exceptions to this rule are the Argus and Octans associations, which formed outside the Sun’s galactocentric radius. Variations in birth heights of the stellar associations suggest that they were born in a filamentary and corrugated disc of molecular clouds, similar to that inferred from the current filamentary molecular cloud distribution and dust extinction maps. Multiple spiral arm features with different but near corotation pattern speeds and at different heights could account for the stellar association birth sites. We find that the young stellar associations are located in between peaks in the radial/tangential (UV) stellar velocity distribution for stars in the solar neighbourhood. This would be expected if they were born in a spiral arm, which perturbs stellar orbits that cross it. In contrast, stellar associations seem to be located near peaks in the vertical phase-space distribution, suggesting that the gas in which stellar associations are born moves vertically together with the low-velocity dispersion disc stars.

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The Mass-Luminosity Relation From Binaries

Highlights of Astronomy ◽

10.1017/s1539299600021602 ◽

1998 ◽

Vol 11 (1) ◽

pp. 419-420

Author(s):

David W. Latham

Keyword(s):

Eclipsing Binaries ◽

M Dwarfs ◽

Direct Measurements ◽

Nearby Stars ◽

The Masses ◽

Stellar Masses ◽

M Dwarf ◽

Magnitude Difference ◽

Astrometric Binaries ◽

Better Than

What is known about the masses of main-sequence stars from the analysis of binary orbits? Double-lined eclipsing binaries are the main source of very precise stellar masses and radii (e.g. Andersen 1997), contributing more than 100 determinations with better than 2% precision over the range 0.6 to 20 Mʘ. For lower-mass stars we are forced to turn to nearby systems with astrometric orbits (e.g. Henry et al. 1993). Not only is the number of good mass determinations from such systems smaller, but also the precision is generally poorer. We are approaching an era when interferometers should have a major impact by supplying good astrometric orbits for dozens of double-lined systems. Already we are beginning to see the sorts of results to expect from this (e.g. Torres et al. 1997). Figure 1. Mass vs. absolute V magnitude for eclipsing binaries (circles) and nearby astrometric binaries (squares) Figure 1 is an updated version of a diagram presented by Henry et al. (1993, their Figure 2). It shows the general run of mass determinations from about 10 Mʘ down to the substellar limit near 0.075 Mʘ. Ninety of the points in Figure 1 are for eclipsing binary masses from Andersen’s review (1991) and are plotted as open circles. The results for eclipsing binaries published since 1991 are plotted as 30 filled circles, adopting the same limit of 2% for the mass precision. In most cases the uncertainties are similar to the size of the symbols. Especially noteworthy is the pair of new points for CM Draconis (Metcalfe et al. 1996) with masses near 0.25 Mʘ. Together with the points for YY Geminorum near 0.6 Mʘ, these are the only M dwarfs that have precise mass determinations. For the most part we are forced to rely on nearby stars with astrometric orbits, to fill in the M dwarf region of the diagram. We have used filled squares in Figure 1 for 29 such systems from Henry et al. (1993), updated using 14 new parallaxes from Hipparcos and 4 from the new Yale Parallax Catalog (1995). Gliese 508 is not included, because it is now known to be a triple, while Gliese 67AB, 570BC, and 623AB are not included because there are not yet any direct measurements of the V magnitude difference for these systems.

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Selection of M-dwarfs using Gaia, WISE, and 2MASS

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2823 ◽

2019 ◽

Vol 490 (3) ◽

pp. 4107-4120

Author(s):

J Bentley ◽

C G Tinney ◽

S Sharma ◽

D Wright

Keyword(s):

Absolute Magnitude ◽

Contamination Rate ◽

M Dwarfs ◽

Sky Survey ◽

Model Predictions ◽

Galaxy Model ◽

M Dwarf ◽

Different Sources ◽

Sources Of Contamination ◽

Selection Of

ABSTRACT We present criteria for the selection of M-dwarfs down to G < 14.5 using all-sky survey data, with a view to identifying potential M-dwarfs, to be confirmed spectroscopically by the FunnelWeb survey. Two sets of criteria were developed. The first, based on absolute magnitude in the Gaia G passband, with MG > 7.7, selects 76,392 stars, with 81.0 per cent expected to be M-dwarfs at a completeness of >97 per cent. The second is based on colour and uses Gaia, WISE, and 2MASS all-sky photometry. This criteria identifies 94,479 candidate M-dwarfs, of which between 29.4 per cent and 47.3 per cent are expected to be true M-dwarfs, and which contains 99.6 per cent of expected M-dwarfs. Both criteria were developed using synthetic galaxy model predictions, and a previously spectroscopically classified set of M- and K-dwarfs, to evaluate both M-dwarf completeness and false-positive detections (i.e. the non-M-dwarf contamination rate). Both criteria used in combination demonstrate how each excludes different sources of contamination. We therefore developed a final set of criteria that combines absolute magnitude and colour selection to identify 74,091 stars. All these sets of criteria select numbers of objects feasible for confirmation via massively multiplexed spectroscopic surveys like FunnelWeb.

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