Cool Subdwarf Investigations. Ii. Multiplicity

Jao, Wei-Chun; Mason, Brian D.; Hartkopf, William I.; Henry, Todd J.; Ramos, Stephanie N.

doi:10.1088/0004-6256/137/4/3800

Cited by 34 publications

(41 citation statements)

References 42 publications

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“…In addition, J12025+084 (M1.5 V; ζ = 0.898 -LHS 320) was classified by Gizis (1997) as an sdM2.0 star and was investigated extensively afterwards with high-resolution imagers (Gizis & Reid 2000;Riaz et al 2008;Jao et al 2009;Lodieu et al 2009). However, we failed to detect any subdwarf signpost in our high signal-to-noise spectrum, which is partly consistent with the metallicity [Fe/H] = −0.6±0.3 measured by Rajpurohit et al (2014).…”

Section: Metallicitymentioning

confidence: 99%

CARMENES input catalogue of M dwarfs

Alonso-Floriano¹,

Morales²,

Caballero³

et al. 2015

A&A

195

178

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Context. CARMENES is a stabilised, high-resolution, double-channel spectrograph at the 3.5 m Calar Alto telescope. It is optimally designed for radial-velocity surveys of M dwarfs with potentially habitable Earth-mass planets. Aims. We prepare a list of the brightest, single M dwarfs in each spectral subtype observable from the northern hemisphere, from which we will select the best planet-hunting targets for CARMENES. Methods. In this first paper on the preparation of our input catalogue, we compiled a large amount of public data and collected lowresolution optical spectroscopy with CAFOS at the 2.2 m Calar Alto telescope for 753 stars. We derived accurate spectral types using a dense grid of standard stars, a double least-squares minimisation technique, and 31 spectral indices previously defined by other authors. Additionally, we quantified surface gravity, metallicity, and chromospheric activity for all the stars in our sample. Results. We calculated spectral types for all 753 stars, of which 305 are new and 448 are revised. We measured pseudo-equivalent widths of Hα for all the stars in our sample, concluded that chromospheric activity does not affect spectral typing from our indices, and tabulated 49 stars that had been reported to be young stars in open clusters, moving groups, and stellar associations. Of the 753 stars, two are new subdwarf candidates, three are T Tauri stars, 25 are giants, 44 are K dwarfs, and 679 are M dwarfs. Many of the 261 investigated dwarfs in the range M4.0-8.0 V are among the brightest stars known in their spectral subtype. Conclusions. This collection of low-resolution spectroscopic data serves as a candidate target list for the CARMENES survey and can be highly valuable for other radial-velocity surveys of M dwarfs and for studies of cool dwarfs in the solar neighbourhood.

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Section: Metallicitymentioning

confidence: 99%

CARMENES input catalogue of M dwarfs

Alonso-Floriano¹,

Morales²,

Caballero³

et al. 2015

A&A

195

178

View full text Add to dashboard Cite

show abstract

“…The 1324 nearby K and M dwarfs with parallaxes placing them within 25 pc were selected using spectral types and a color cutoff of V − K s >1.9, and are represented by the blue curve. The red line indicates the 167 K and M subdwarfs observed during our CTIOPI program with new or revised parallaxes from RECONS, supplemented with confirmed subdwarfs collected from the literature (Ryan & Norris 1991;Carney et al 1994;Hawley et al 1996;Gizis 1997;Cayrel de Strobel et al 2001;Burgasser et al 2003;Lépine et al 2003a;Woolf & Wallerstein 2005;Jao et al 2009;10 The reduced proper motion, "H," is defined as H m 5 log 5…”

Section: Tangential Velocitymentioning

confidence: 99%

The Solar Neighborhood. XLII. Parallax Results from the CTIOPI 0.9 m Program—Identifying New Nearby Subdwarfs Using Tangential Velocities and Locations on the H–R Diagram

Jao

Henry²,

Winters

et al. 2017

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Parallaxes, proper motions, and optical photometry are presented for 51 systems consisting of 37 cool subdwarf and 14 additional high proper motion systems. Thirty-seven systems have parallaxes reported for the first time, 15 of which have proper motions of at least 1″ yr −1 . The sample includes 22 newly identified cool subdwarfs within 100 pc, of which three are within 25 pc, and an additional five subdwarfs from 100 to 160 pc. Two systems-LSR 1610-0040 AB and LHS 440 AB-are close binaries exhibiting clear astrometric perturbations that will ultimately provide important masses for cool subdwarfs. We use the accurate parallaxes and proper motions provided here, combined with additional data from our program and others, to determine that effectively all nearby stars with tangential velocities greater than 200 km s −1 are subdwarfs. We compare a sample of 167 confirmed cool subdwarfs to nearby main sequence dwarfs and Pleiades members on an observational Hertzsprung-Russell diagram using M V versus(V − K s ) to map trends of age and metallicity. We find that subdwarfs are clearly separated for spectral types K5-M5, indicating that the low metallicities of subdwarfs set them apart in the H-R diagram for (V − K s )=3-6. We then apply the tangential velocity cutoff and the subdwarf region of the H-R diagram to stars with parallaxes from Gaia Data Release 1 and the MEarth Project to identify a total of 29 new nearby subdwarf candidates that fall clearly below the main sequence.

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“…Jao et al (2009) Table 2. Figure 6 illustrates the agreeable match in our astrometric fits when proper motion and parallax For a distance of 15.83 ± 0.96 pc, we derive the absolute H and W 2 magnitudes that are given in Table 1.…”

Section: The Companionship Of Wise 2005+5424 and Wolf 1130mentioning

confidence: 99%

The Exemplar T8 Subdwarf Companion of Wolf 1130

Mace

Kirkpatrick

Cushing

et al. 2013

ApJ

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We have discovered a wide separation (188. 5) T8 subdwarf companion to the sdM1.5+WD binary Wolf 1130. Companionship of WISE J200520.38+542433.9 is verified through common proper motion over a ∼3 yr baseline. Wolf 1130 is located 15.83 ± 0.96 pc from the Sun, placing the brown dwarf at a projected separation of ∼3000 AU. Near-infrared colors and medium resolution (R ≈ 2000-4000) spectroscopy establish the uniqueness of this system as a high-gravity, low-metallicity benchmark. Although there are a number of low-metallicity T dwarfs in the literature, WISE J200520.38+542433.9 has the most extreme inferred metallicity to date with [Fe/H] = −0.64 ± 0.17 based on Wolf 1130. Model comparisons to this exemplar late-type subdwarf support it having an old age, a low metallicity, and a small radius. However, the spectroscopic peculiarities of WISE J200520.38+542433.9 underscore the importance of developing the low-metallicity parameter space of the most current atmospheric models.

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Cool Subdwarf Investigations. Ii. Multiplicity

Cited by 34 publications

References 42 publications

CARMENES input catalogue of M dwarfs

CARMENES input catalogue of M dwarfs

The Solar Neighborhood. XLII. Parallax Results from the CTIOPI 0.9 m Program—Identifying New Nearby Subdwarfs Using Tangential Velocities and Locations on the H–R Diagram

The Exemplar T8 Subdwarf Companion of Wolf 1130

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