The Palomar/MSU Nearby Star Spectroscopic Survey.II.The Southern M Dwarfs and Investigation of Magnetic Activity

Hawley, Suzanne L.; Gizis, John E.; Reid, I. Neill

doi:10.1086/118222

Cited by 462 publications

(597 citation statements)

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“…Overall, 29 of 1399 objects have ζ 0.80, suggesting that only ∼2% of this sample could be high C/O ratio M dwarfs, but many (if not all) are metal-poor. A more heterogenous, and partially overlapping, sample is the two thousand late-K and M dwarfs within 25 parsecs observed by the PMSU survey (Reid et al 1995;Hawley et al 1996), which approximates a volume-limited sample. Of these stars, less than one percent show the sdM type (including Kapteyn's Star, GJ 191), and these are consistent with the expected numbers of kinematics of the metal-poor (thick-disk/halo) population.…”

Section: Observational Constraintsmentioning

confidence: 99%

M dwarfs and the fraction of high carbon-to-oxygen stars in the solar neighbourhood

Gizis

Marks

Hauschildt³

2015

Mon. Not. R. Astron. Soc.

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We investigate the frequency of high carbon-to-oxygen (C/O = 0.9) M dwarf stars in the solar neighbourhood. Using synthetic spectra, we find that such M dwarfs would have weaker TiO bands relative to hydride features. Similar weakening has already been detected in M-subdwarf (sdM) stars. By comparing to existing spectroscopic surveys of nearby stars, we show that less than one percent of nearby stars have high carbon-to-oxygen ratios. This limit does not include stars with C/O= 0.9, [m/H]> 0.3, and [C/Fe]> 0.1, which we predict to have low-resolution optical spectra similar to solar metallicity M dwarfs.

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Section: Observational Constraintsmentioning

confidence: 99%

M dwarfs and the fraction of high carbon-to-oxygen stars in the solar neighbourhood

Gizis

Marks

Hauschildt³

2015

Mon. Not. R. Astron. Soc.

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“…Magnetic activity is best understood at optical wavelengths, where large spectroscopic studies such as the Sloan Digital Sky Survey (York et al 2000;Abazajian et al 2009, SDSS) have enabled a statistical treatment of M dwarf activity, particularly by using Hα emission as a diagnostic (L L ; H bol a West et al 2004West et al , 2008West et al , 2011. West et al (2008) showed that activity in the optical varies as a function of both spectral type and stellar age, with a peak in the active fraction occurring near a spectral type of M8 (Reid et al 1995;Hawley et al 1996;Gizis et al 2000;West et al 2004).…”

Section: Introductionmentioning

confidence: 99%

A Catalog of Galex Ultraviolet Emission From Spectroscopically Confirmed M Dwarfs*

Jones¹,

West²

2016

ApJ

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We present a catalog of Galaxy Evolution Explorer Near-UV (NUV) and Far-UV (FUV) photometry for the Palomar/MSU and SDSS DR7 spectroscopic M dwarf catalogs. The catalog contains NUV measurements matched to 577 spectroscopically confirmed M dwarfs and FUV measurements matched to 150 spectroscopically confirmed M dwarfs. Using these data, we find that NUV and FUV luminosities strongly correlate with Hα emission, a typical indicator of magnetic activity in M dwarfs. We also examine the fraction of M dwarfs with varying degrees of strong line emission at NUV wavelengths. Our results indicate that the frequency of M dwarf NUV emission peaks at intermediate spectral types, with at least ∼30% of young M4-M5 dwarfs having some level of activity. For mid-type M dwarfs, we show that NUV emission decreases with distance from the Galactic plane, a proxy for stellar age. Our complete matched source catalog is available online.

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“…How strong is chromospheric activity? By adding the spectroscopic survey of nearby stars by Hawley et al [11], the frequency of activity from K7 (T ef f ≈ 4200K down to L8 (T ef f ≈ 1400K?) is plotted in Fig.…”

Section: Activitymentioning

confidence: 99%

“…Over the (stellar) range K7 to M7, the frequency of activity increases as cooler, lower-mass stars are considered. The kinematics of field M dwarfs [11] and observations of open clusters [12] both indicate that the active stars are younger than the inactive stars, and that the increase in the frequency of emission reflects the longer lifetime of high activity levels.…”

Section: Activitymentioning

confidence: 99%

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Activity and Kinematics of M and L Dwarfs

Gizis

2001

Ultracool Dwarfs

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Abstract. I discuss observations of two traditional age indicators, chromospheric activity and kinematics, in late-M and L dwarfs near the hydrogen-burning limit. The frequency and strength of chromospheric activity disappears rapidly as a function of temperature over spectral types M8-L4. There is evidence that young late-M and L dwarfs have weaker activity than older ones, the opposite of the traditional stellar ageactivity relation. The kinematics of L dwarfs confirm that lithium L dwarfs are younger than non-lithium dwarfs.

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The Palomar/MSU Nearby Star Spectroscopic Survey.II.The Southern M Dwarfs and Investigation of Magnetic Activity

Cited by 462 publications

References 0 publications

M dwarfs and the fraction of high carbon-to-oxygen stars in the solar neighbourhood

M dwarfs and the fraction of high carbon-to-oxygen stars in the solar neighbourhood

A Catalog of Galex Ultraviolet Emission From Spectroscopically Confirmed M Dwarfs*

Activity and Kinematics of M and L Dwarfs

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