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 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 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 1995PASP..107..375O; McCarthy et al. 1998SPIE.3355...81M 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 2008ApJ...681..594H). The latest spectral types of the 2008 May run
were published in Herczeg et al. (2009ApJ...696.1589H 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:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table14.dat 104 399 Stellar Properties
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See also:
J/A+A/297/391 : T Tauri stars ROSAT survey (Neuhaeuser+, 1995)
Byte-by-byte Description of file: table14.dat
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Bytes Format Units Label Explanations
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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)
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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.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 20-Jun-2017