A PCA approach to stellar effective temperatures

Bermejo, Juan; Ramos, A. Asensio; Prieto, C. Allende

doi:10.1051/0004-6361/201220961

Cited by 28 publications

(24 citation statements)

References 19 publications

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“…Torres et al (2006) quote a K0V spectral type, v sin i = 14.6 km s −1 and W Li ≃ 300 mÅ. Muñoz Bermejo et al (2013), from the analysis of our ELODIE spectrum, found T eff = 5221 K. Our determinations (K0V, T eff = 5207 K, v sin i = 14.3 km s −1 , W Li = 277±25 mÅ) are in excellent agreement with the aforementioned values from the literature. A visual companion at 5.…”

Section: Appendix A: the Datasupporting

confidence: 90%

“…#21 RasTyc 2036+3456 (=TYC 2694-1627-1). A temperature about 160 K cooler than our value was found by Muñoz Bermejo et al (2013) from the analysis of our ELODIE spectrum. The Hα line is filled in by core emission.…”

Section: # Namecontrasting

confidence: 73%

“…#20 RasTyc 2016+3106 (=HD 332091) was identified as the optical counterpart of the X-ray source 1RXS J200449.5-023915 by Haakonsen & Rutledge (2009). A temperature about 350 K cooler than our value was found by Muñoz Bermejo et al (2013), who analyzed the same ELODIE spectra acquired by us. We note that our temperature value, T eff =5082 K is closer to the value of 5500 K derived with the Pecaut & Mamajek (2013) calibrations from the dereddened color index (B −V ) 0 = 0.715 mag than the value T eff =4704 K reported by Muñoz Bermejo et al (2013).…”

Section: # Namesupporting

confidence: 54%

“…A temperature about 350 K cooler than our value was found by Muñoz Bermejo et al (2013), who analyzed the same ELODIE spectra acquired by us. We note that our temperature value, T eff =5082 K is closer to the value of 5500 K derived with the Pecaut & Mamajek (2013) calibrations from the dereddened color index (B −V ) 0 = 0.715 mag than the value T eff =4704 K reported by Muñoz Bermejo et al (2013). The Hα line is a faint emission feature in all the three ELODIE spectra with a variation of ≈ 30%.…”

Section: # Namecontrasting

confidence: 48%

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A spectroscopic survey of the youngest field stars in the solar neighborhood

Frasca

Guillout

Klutsch

et al. 2018

A&A

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Context. Star formation in the solar neighborhood is mainly traced by young stars in open clusters, associations and in the field, which can be identified, e.g., by their X-ray emission. The determination of stellar parameters for the optical counterparts of X-ray sources is crucial for a full characterization of these stars. Aims. This work extends the spectroscopic study of the RasTyc sample, obtained by the cross-correlation of the TYCHO and ROSAT All-Sky Survey catalogs, to stars fainter than V = 9.5 mag and it is aimed to the identification of sparse populations of young stars in the solar neighborhood. Methods. We acquired 625 high-resolution spectra for 443 presumabily young stars with four different instruments in the Northern hemisphere. The radial and rotational velocity (v sin i) of our targets are measured by means of the cross-correlation technique, which is also helpful to discover single-lined (SB1), double-lined spectroscopic binaries (SB2), and multiple systems. We use the code ROTFIT for performing an MK spectral classification and for determining the atmospheric parameters (T eff , log g, [Fe/H]) and v sin i of the single stars and SB1 systems. For these objects, the spectral subtraction of slowly rotating templates is used to measure the equivalent widths of the Hα and Li i 6708Å lines, which enables us to derive their chromospheric activity level and lithium abundance. We make use of Gaia DR1 parallaxes and proper motions for locating the targets in the HR diagram and for computing the space velocity components of the youngest objects. Results. We find a remarkable fraction (at least 35 %) of binaries and multiple systems. On the basis of the lithium abundance, the sample of single stars and SB1 systems appears to be mostly (∼ 60 %) composed of stars younger than the members of the UMa cluster. The remaining sources are in the age range between the UMa and Hyades clusters (∼ 20 %) or older (∼ 20 %). In total, we identify 42 very young (PMS-like) stars, which lie above or very close to the Pleiades upper envelope of the lithium abundance. A significant fraction (∼ 12 %) of evolved stars (giants and subgiants) is also present in our sample. Some of them (∼ 36 %) are also lithium rich (A(Li)> 1.4).

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Section: Appendix A: the Datasupporting

confidence: 90%

Section: # Namecontrasting

confidence: 73%

Section: # Namesupporting

confidence: 54%

Section: # Namecontrasting

confidence: 48%

See 2 more Smart Citations

A spectroscopic survey of the youngest field stars in the solar neighborhood

Frasca

Guillout

Klutsch

et al. 2018

A&A

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“…3 shows, this concerns relatively small corrections of the continuum level that never exceed a few percent. As mentioned earlier by Muñoz Bermejo et al (2013), this procedure may be debatable, but we found it satisfactory, and it was consistently applied to all the spectra we used.…”

Section: Training Databasementioning

confidence: 56%

Inversion of stellar fundamental parameters from ESPaDOnS and Narval high-resolution spectra

Paletou

Böhm

Watson

et al. 2014

A&A

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The general context of this study is the inversion of stellar fundamental parameters from high-resolution Echelle spectra. We aim at developing a fast and reliable tool for the post-processing of spectra produced by ESPaDOnS and Narval spectropolarimeters. Our inversion tool relies on principal component analysis. It allows reducing dimensionality and defining a specific metric for the search of nearest neighbours between an observed spectrum and a set of observed spectra taken from the Elodie stellar library. Effective temperature, surface gravity, total metallicity, and projected rotational velocity are derived. Various tests presented in this study that were based solely on information coming from a spectral band centred on the Mg  b-triplet and had spectra from FGK stars are very promising.

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Faint solar analogues at the limit of no reddening

Giribaldi

Mello

Amôres

et al. 2019

A&A

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Context. The flux distribution of solar analogues is required for calculating the spectral albedo of solar system bodies such as asteroids and trans-Neptunian objects. Ideally a solar analogue should be comparatively faint as the target of interest, but very few analogues fainter than V = 9 mag have been identified so far. Only atmospheric parameters equal to solar guarantee a flux distribution equal to solar as well, while only photometric colours equal to solar do not. Reddening is also a factor to consider when selecting faint analogue candidates. Aims. Our aim is to implement the methodology for identifying faint analogues at the limit of precision allowed by the current spectroscopic surveys. We quantify the precision attainable for the atmospheric parameters of effective temperature (Teff), metallicity ([Fe/H]), and surface gravity (log g) when derived from moderately low-resolution (R = 8000) spectra with S∕N ~ 100. We estimate the significance of reddening at 100–300 pc from the Sun. Methods. We used the less precise photometry in the HIPPARCOS catalogue to select potential analogues with V ~ 10.5 mag (located at ~135 pc). We calibrated Teff and [Fe/H] as functions of equivalent widths of spectral indices by means of the principal component analysis regression. We derived log g, mass, radius, and age from the atmospheric parameters, Gaia parallaxes, and evolutionary tracks. We evaluated the presence of reddening for the candidates by underestimations of photometric Teff with respect to those derived by spectral indices. These determinations were validated with extinction maps. Results. We obtained the atmospheric parameters Teff, [Fe/H], and log g with precision of 97 K, 0.06 dex, 0.05 dex, respectively. From 21 candidates analysed, we identify five solar analogues: HIP 991, HIP 5811, and HIP 69477 have solar parameters within 1σ errors, and HIP 55619 and HIP 61835 within 2σ errors. Six other stars have Teff close to solar, but slightly lower [Fe/H]. Our analogues show no evidence of reddening except for four stars, that present E(B−V) ≥ 0.06 mag, translating to at least a 200 K decrease in photometric Teff.

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A PCA approach to stellar effective temperatures

Cited by 28 publications

References 19 publications

A spectroscopic survey of the youngest field stars in the solar neighborhood

A spectroscopic survey of the youngest field stars in the solar neighborhood

Inversion of stellar fundamental parameters from ESPaDOnS and Narval high-resolution spectra

Faint solar analogues at the limit of no reddening

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