Probing M subdwarf metallicity with an esdK5+esdM5.5 binary

Pavlenko, Ya. V.; Zhang, ZH; Gálvez-Ortiz, M. C.; Kushniruk, Iryna; Jones, H. R. A.

doi:10.1051/0004-6361/201526810

Cited by 15 publications

(16 citation statements)

References 36 publications

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“…(Table 8) between early-type dM, sdM, esdM, and usdM derived from fig. 9 of Pavlenko et al (2015). Objects with T eff > 3500 K (yellow, red, blue and black crosses are for dM, sdM, esdM, and usdM, respectively) are from Woolf & Wallerstein (2006) and Woolf, Lépine, & Wallerstein (2009 Pinfield et al 2012).…”

Section: Metallicity Ranges Of the Subclasses Of M And L Subdwarfsmentioning

confidence: 99%

“…J210105.37-065633.0 AB (esdM1.5+esdM5.5; Zhang et al 2013;Pavlenko et al 2015) would be very useful if the metallicity subclasses of early-late M subdwarfs are to be refined. Table 8 summarises both subclass schemes, and indicates approximate links between subclasses, metallicity and kinematic populations.…”

Section: Metallicity Ranges Of the Subclasses Of M And L Subdwarfsmentioning

confidence: 99%

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Primeval very low-mass stars and brown dwarfs – I. Six new L subdwarfs, classification and atmospheric properties

Zhang

Pinfield

Galvez-Ortiz

et al. 2016

Mon. Not. R. Astron. Soc.

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We have conducted a search for L subdwarf candidates within the photometric catalogues of the UKIRT Infrared Deep Sky Survey and Sloan Digital Sky Survey. Six of our candidates are confirmed as L subdwarfs spectroscopically at optical and/or nearinfrared wavelengths. We also present new optical spectra of three previously known L subdwarfs (WISEA J001450.17-083823.4, 2MASS J00412179+3547133 and ULAS J124425.75+102439.3). We examined the spectral type and metallicity classification of subclasses of known L subdwarfs. We summarized the spectroscopic properties of L subdwarfs with different spectral types and subclasses. We classify these new L subdwarfs by comparing their spectra to known L subdwarfs and L dwarf standards. We estimate temperatures and metallicities of 22 late-type M and L subdwarfs by comparing their spectra to BT-Settl models. We find that L subdwarfs have temperatures between 1500 and 2700 K, which are higher than similar-typed L dwarfs by around 100-400 K depending on different subclasses and subtypes. We constrained the metallicity ranges of subclasses of M, L, and T subdwarfs. We also discussed the spectral-type and absolute magnitude relationships for L and T subdwarfs.

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Section: Metallicity Ranges Of the Subclasses Of M And L Subdwarfsmentioning

confidence: 99%

Section: Metallicity Ranges Of the Subclasses Of M And L Subdwarfsmentioning

confidence: 99%

Primeval very low-mass stars and brown dwarfs – I. Six new L subdwarfs, classification and atmospheric properties

Zhang

Pinfield

Galvez-Ortiz

et al. 2016

Mon. Not. R. Astron. Soc.

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“…The signal-to-noise ratio of the spectrum is ∼35 in Hα line. For more details on observations and reduction procedures please see [12]. * nondanone@gmail.com On the rst step of our work we used the plane-parallel model atmosphere 5777/4.44/0.0 described in [10] for the Sun, the PDK (Peterson-Dalle-Kurucz) [13] model atmosphere with parameters 4300/1.…”

Section: Observations Arcturus and The Sunmentioning

confidence: 99%

“…We adopted V t = 0.75 km/s for the Sun based on 48 specially selected Fe E lines and V t = 1 km/s for Arcturus based on 44 Fe E lines, according to [12].…”

Section: Microturbulent Velocitymentioning

confidence: 99%

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Surface gravity and effective temperature of the K5 subdwarf G 224-58 A and Arcturus from the fits to Ti and MgH lines

Kushniruk

Pavlenko

Gálvez-Ortiz

et al. 2016

Adv.Astron.Spa.Physics

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We discuss here the results obtained in the determination of effective temperatures and metallicities of late-type stars. We provide the abundances of MgH, TiI and TiII, with a list of selected lines, for the red giant of Arcturus and the metal-poor K subdwarf G 224-58 A. The Sun was used as a template star. After computing synthetic spectra for model atmospheres with different Teff and logg values, we used minimization procedures to determine the best fits to the observed features. The determination of Ti abundances was carried out in the framework of a self-consistent approach developed by Pavlenko et al. (2012). In the case of MgH we used similar minimization procedure. We present here the combination of two different approaches based on the fits performed to Ti and MgH, respectively. The resulting effective temperatures are Teff=4300 K for Arcturus and Teff=4600 K for G 224-58 A, where both solutions are degenerated with logg.

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Fundamental M-dwarf parameters from high-resolution spectra using PHOENIX ACES models

Passegger

Berg

Reiners

2016

A&A

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M-dwarf stars are the most numerous stars in the Universe; they span a wide range in mass and are in the focus of ongoing and planned exoplanet surveys. To investigate and understand their physical nature, detailed spectral information and accurate stellar models are needed. We use a new synthetic atmosphere model generation and compare model spectra to observations. To test the model accuracy, we compared the models to four benchmark stars with atmospheric parameters for which independent information from interferometric radius measurements is available. We used χ 2 -based methods to determine parameters from high-resolution spectroscopic observations. Our synthetic spectra are based on the new PHOENIX grid that uses the ACES description for the equation of state. This is a model generation expected to be especially suitable for the low-temperature atmospheres. We identified suitable spectral tracers of atmospheric parameters and determined the uncertainties in T eff , log g, and [Fe/H] resulting from degeneracies between parameters and from shortcomings of the model atmospheres. The inherent uncertainties we find are σ T eff = 35 K, σ log g = 0.14, and σ [Fe/H] = 0.11. The new model spectra achieve a reliable match to our observed data; our results for T eff and log g are consistent with literature values to within 1σ. However, metallicities reported from earlier photometric and spectroscopic calibrations in some cases disagree with our results by more than 3σ. A possible explanation are systematic errors in earlier metallicity determinations that were based on insufficient descriptions of the cool atmospheres. At this point, however, we cannot definitely identify the reason for this discrepancy, but our analysis indicates that there is a large uncertainty in the accuracy of M-dwarf parameter estimates.

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Probing M subdwarf metallicity with an esdK5+esdM5.5 binary

Cited by 15 publications

References 36 publications

Primeval very low-mass stars and brown dwarfs – I. Six new L subdwarfs, classification and atmospheric properties

Primeval very low-mass stars and brown dwarfs – I. Six new L subdwarfs, classification and atmospheric properties

Surface gravity and effective temperature of the K5 subdwarf G 224-58 A and Arcturus from the fits to Ti and MgH lines

Fundamental M-dwarf parameters from high-resolution spectra using PHOENIX ACES models

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