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J/ApJ/786/97       Photospheric properties of T Tauri stars     (Herczeg+, 2014)

An optical spectroscopic study of T Tauri stars. I. Photospheric properties. Herczeg G.J., Hillenbrand L.A. <Astrophys. J., 786, 97 (2014)> =2014ApJ...786...97H (SIMBAD/NED BibCode)
ADC_Keywords: Stars, pre-main sequence ; Stars, distances ; Spectral types ; Extinction ; Stars, diameters ; Stars, masses ; Stars, ages Keywords: stars: low-mass - stars: pre-main sequence Abstract: Estimates of the mass and age of young stars from their location in the H-R diagram are limited by not only the typical observational uncertainties that apply to field stars, but also by large systematic uncertainties related to circumstellar phenomena. In this paper, we analyze flux-calibrated optical spectra to measure accurate spectral types and extinctions of 281 nearby T Tauri stars (TTSs). The primary advances in this paper are (1) the incorporation of a simplistic accretion continuum in optical spectral type and extinction measurements calculated over the full optical wavelength range and (2) the uniform analysis of a large sample of stars, many of which are well known and can serve as benchmarks. Comparisons between the non-accreting TTS photospheric templates and stellar photosphere models are used to derive conversions from spectral type to temperature. Differences between spectral types can be subtle and difficult to discern, especially when accounting for accretion and extinction. The spectral types measured here are mostly consistent with spectral types measured over the past decade. However, our new spectral types are one to two subclasses later than literature spectral types for the original members of the TW Hya Association (TWA) and are discrepant with literature values for some well-known members of the Taurus Molecular Cloud. Our extinction measurements are consistent with other optical extinction measurements but are typically 1 mag lower than near-IR measurements, likely the result of methodological differences and the presence of near-IR excesses in most CTTSs. As an illustration of the impact of accretion, spectral type, and extinction uncertainties on the H-R diagrams of young clusters, we find that the resulting luminosity spread of stars in the TWA is 15%-30%. The luminosity spread in the TWA and previously measured for binary stars in Taurus suggests that for a majority of stars, protostellar accretion rates are not large enough to significantly alter the subsequent evolution. Description: We obtained low resolution optical spectra with the Double Spectrograph (DBSP; Oke & Gunn 1982PASP...94..586O) on the Hale 200 inch telescope at Palomar Observatory on 2008 January 18-21 and 2008 December 28-30, and with the Low Resolution Imaging Spectrograph (LRIS; Oke et al. 1995PASP..107..375O; McCarthy et al. 1998SPIE.3355...81M) on Keck I on 2006 November 23 and 2008 May 28. The entire sample of the 2006 Keck observations was published in Herczeg & Hillenbrand (2008ApJ...681..594H). The latest spectral types of the 2008 May run were published in Herczeg et al. (2009ApJ...696.1589H). The Atmospheric Dispersion Corrector (Phillips et al. 2006SPIE.6269E..1OP) was used for the 2008 May run but was not yet available in 2006 November. Both DBSP and LRIS use a dichroic to split the light into red and blue beams at ∼5600 Å. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table14.dat 104 399 Stellar Properties
See also: J/A+A/297/391 : T Tauri stars ROSAT survey (Neuhaeuser+, 1995) Byte-by-byte Description of file: table14.dat
Bytes Format Units Label Explanations
1- 15 A15 --- Name Source identifier 17- 41 A25 --- OName 2MASS identifier or other name if no 2MASS identifier 43- 53 A11 "date" Date Date of the Observation 56- 58 I3 pc d Distance 60- 63 A4 --- SpType Spectral type 64 A1 --- RFlag [rc] Results flag (1) 66- 70 F5.2 mag AV ? V band extinction (2) 73- 78 F6.2 [cW/m2/nm] logF Log photospheric flux at 7510 Å (3) 80- 83 F4.2 --- r7510 ? Veiling at 7510 Å (4) 85- 89 F5.2 [Lsun] logL ? Log luminosity (4) 91- 94 F4.2 Rsun Rad ? Radius (4) 96-100 F5.2 Msun Mass ? Mass (4) 102-104 F3.1 [yr] logA ? Log age (5)
Note (1): Flag as follows: r = Results based only on red spectrum; c = Results affected by strong accretion. Note (2): AV calculated with RV=3.1, except for RV=4 for DoAr 21 and SR 21 and RV=5.5 for IRS 48 and V892 Tau. Note (3): Corrected for listed AV. In units of erg/s/cm2/Å. Note (4): Blank for sources with no measured SpType. Note (5): A logA=5 inidcates 5 or younger.
History: From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 20-Jun-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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