Intermediate Resolution Near-Infrared Spectroscopy of 36 Late M Dwarfs

Deshpande, Rohit; Martín, E. L.; Montgomery, M. M.; Osorio, M. R. Zapatero; Rodler, F.; Burgo, C. del; Bao, N. Phan; Lyubchik, Y.; Tata, R.; Bouy, H.; Pavlenko, Ya. V.

doi:10.1088/0004-6256/144/4/99

Cited by 42 publications

(33 citation statements)

References 81 publications

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“…The frequency of fast rotators in our sample (v rot ≥ 3 km s −1 corresponding to Prot shorter than about 3 days) is 55%, which is in good agreement with previous estimates based on spectroscopic measurements of rotational broadening (Deshpande et al 2012) that find about 65% of late dMs with v sin i higher than 12 km s −1 . The high precision of Kepler allows us to obtain reliable rotational periods in 61% of the sample, a much higher detection rate than in ground-based transit surveys like MEarth, which reported rotation periods for 41 out of 273 (i.e., 15%) fully convective M dwarfs (Irwin et al 2011), but comparable to the Kepler-based analysis for M dwarfs (McQuillan et al 2013), which detected rotation periods in 63% of their sample (only one object in common with our sample).…”

Section: Stellar Variability 421 Rotational Periodssupporting

confidence: 92%

Keplerobservations of very low-mass stars

Martín¹,

Cabrera²,

Martioli³

et al. 2013

A&A

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Observations of very low-mass stars with Kepler represent an excellent opportunity to search for planetary transits and to characterize optical photometric variability at the cool end of the stellar mass distribution. In this paper, we present low-resolution red optical spectra that allow us to identify 18 very low-mass stars that have Kepler light curves available in the public archive. Spectral types of these targets are found to lie in the range dM4.5-dM8.5, implying spectrophotometric distances from 17 pc to 80 pc. Limits to the presence of transiting planets are set by modeling of the Kepler light curves. We find that the size of the planets detectable by Kepler around these small stars typically lies in the range 1 to 5 Earth radii within the habitable regions (P ≤ 10 days). We identify one candidate transit with a period of 1.26 days whose light curve resembles a planet slightly smaller than the Moon. However, our pixel by pixel analysis of the Kepler data shows that the signal most likely arises from a background contaminating eclipsing binary. For 11 of these objects reliable photometric periods shorter than 7 days are derived, and are interpreted as rotational modulation of magnetic cool spots. For 3 objects we find possible photometric periods longer than 50 days that require confirmation. The H α emission measurements and flare rates are used as proxies for chromospheric activity, and transversal velocities are used as an indicator of dynamical ages. These data allow us to discuss the relationship between magnetic activity and detectability of planetary transits around very low-mass stars. We show that super-Earth planets with sizes around 2 Earth radii are detectable with Kepler around about two thirds of the stars in our sample, independently of their level of chromospheric activity.

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Section: Stellar Variability 421 Rotational Periodssupporting

confidence: 92%

Keplerobservations of very low-mass stars

Martín¹,

Cabrera²,

Martioli³

et al. 2013

A&A

Self Cite

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“…For those stars with only one epoch of observations (two spectra), the uncertainty stated is the half range of the v sin i values. Our infrared v sin i values agree with those estimated from optical spectra and recently published J (1.25 μm) NIRSPEC spectra (Reiners & Basri 2010;Deshpande et al 2012; see Table 4). When we combine our v sin i values with those from the literature (see Figure 4), our values lie squarely within the spread of values from previous studies (Blake et al 2010;Mohanty & Basri 2003;Reiners & Basri 2010), which show a trend of increasing minimum rotational velocity with later spectral type.…”

Section: Rotational Velocities Of Late-m Dwarfssupporting

confidence: 90%

Keck Nirspec Radial Velocity Observations of Late-M Dwarfs

Tanner

White

Bailey

et al. 2012

ApJS

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We present the results of an infrared spectroscopic survey of 23 late-M dwarfs with the NIRSPEC echelle spectrometer on the Keck II telescope. Using telluric lines for wavelength calibration, we are able to achieve measurement precisions of down to 45 m s −1 for our late-M dwarfs over a one-to four-year long baseline. Our sample contains two stars with radial velocity (RV) variations of >1000 m s −1. While we require more measurements to determine whether these RV variations are due to unseen planetary or stellar companions or are the result of starspots known to plague the surface of M dwarfs, we can place upper limits of <40 M J sin i on the masses of any companions around those two M dwarfs with RV variations of <160 m s −1 at orbital periods of 10-100 days. We have also measured the rotational velocities for all the stars in our late-M dwarf sample and offer our multiorder, high-resolution spectra over 2.0-2.4 μm to the atmospheric modeling community to better understand the atmospheres of late-M dwarfs.

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“…Measurements were taken from the following references: BailerJones (2004), Berger et al (2008), Blake et al (2007), Bochanski et al (2011), Caballero et al (2004, Crossfield et al (2014), Del Burgo et al (2009), Deshpande et al (2012, Gizis et al (2013), Joergens & Guenther (2001), Jones et al (2005), Konopacky et al (2012), Kurosawa et al (2006), Martin et al (1997), Mohanty et al (2003Mohanty et al ( , 2005, Muzerolle et al (2003), Reid et al (2002), Reiners & Basri (2006, 2010, Reiners et al (2007), Rice et al (2010), Snellen et al (2014), Tinney & Reid (1998), White & Basri (2003), and Zapatero .…”

Section: Projected Rotation Velocitymentioning

confidence: 99%

Doppler imaging of exoplanets and brown dwarfs

Crossfield

2014

A&A

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Doppler imaging produces 2D global maps of rotating objects using high-dispersion spectroscopy. When applied to brown dwarfs and extrasolar planets, this technique can constrain global atmospheric dynamics and/or magnetic effects on these objects in unprecedented detail. I present the first quantitative assessment of the prospects for Doppler imaging of substellar objects with current facilities and with future giant ground-based telescopes. Observations will have the greatest sensitivity in K band, but the H and L bands will also be useful for these purposes. To assess the number and availability of targets, I also present a compilation of all measurements of photometric variability, rotation period (P), and projected rotational velocity (v sin i) for all known brown dwarfs. Several bright objects are already accessible to Doppler imaging with currently available instruments. With the development of giant ground-based telescopes, Doppler imaging will become feasible for many dozens of brown dwarfs and for the few brightest directly imaged extrasolar planets (such as β Pic b). The present set of measurements of P, v sin i, and variability are incomplete for many objects, and the sample is strongly biased toward early-type objects (

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Intermediate Resolution Near-Infrared Spectroscopy of 36 Late M Dwarfs

Cited by 42 publications

References 81 publications

Keplerobservations of very low-mass stars

Keplerobservations of very low-mass stars

Keck Nirspec Radial Velocity Observations of Late-M Dwarfs

Doppler imaging of exoplanets and brown dwarfs

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