J/A+A/632/A46 TW Hydrae association with X-shooter (Venuti+, 2019)
X-shooter spectroscopy of young stars with disks.
The TW Hydrae association as a probe of the final stages of disk accretion.
Venuti L., Stelzer B., Alcala J.M., Manara C.F., Frasca A., Jayawardhana R.,
Antoniucci S., Argiroffi C., Natta A., Nisini B., Randich S., Scholz A.
<Astron. Astrophys. 632, A46 (2019)>
=2019A&A...632A..46V 2019A&A...632A..46V (SIMBAD/NED BibCode)
ADC_Keywords: Stars, M-type ; Stars, pre-main sequence ; Accretion ;
Line Profiles; Spectra, infrared; Spectra, ultraviolet;
Spectroscopy
Keywords: accretion, accretion disks - techniques: spectroscopic -
stars: low-mass - stars: pre-main sequence -
open clusters and associations: individual: TWA
Abstract:
Measurements of the protoplanetary disk frequency in young star
clusters of different ages indicate disk lifetimes <10Myr. However,
our current knowledge of how mass accretion in young stars evolves
over the lifespans of disks is subject to many uncertainties,
especially at the lower stellar masses. In this study, we investigate
ongoing accretion activity in the TW Hydrae association (TWA), the
closest association of pre-main sequence stars with active disks. The
age (8-10Myr) and the proximity of the TWA render it an ideal target
to probe the final stages of disk accretion down to brown dwarf
masses. The study is based on homogeneous spectroscopic data from
300nm to 2500nm, obtained synoptically with X-shooter, which allows
simultaneous derivation of individual extinction, stellar parameters,
and accretion parameters for each star. The continuum excess emission
diagnostics is used to estimate the accretion luminosities and mass
accretion rates of our disk-bearing targets, and the shape and
intensity of permitted and forbidden emission lines are analyzed to
probe the physics of the star-disk interaction environment.
Description:
The data provided are the reduced, flux-calibrated, and
telluric-corrected X-shooter 1-D spectra for all 14 TWA members
analyzed in our study. Each spectrum is divided into three segments,
UVB, VIS, and NIR. For four of our targets, multiple sets of spectra
were acquired, either at different epochs (TWA27, TWA30A, TWA30B), or
using different slit widths (TWA30A) and/or exposure times (TWA1). As
a result, 19 sets of spectra are included in this dataset. The spectra
are not corrected for Av, which is estimated to be close to 0 for many
of our targets. The wavelengths are expressed in nm and the flux in
erg/s/cm2/nm.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 114 19 List of X-shooter spectra for all TWA targets
fits/* . 57 Individual fits spectra
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Name Object identifier
8- 9 I2 h RAh Right ascension (J2000)
11- 12 I2 min RAm Right ascension (J2000)
14- 19 F6.3 s RAs Right ascension (J2000)
21 A1 --- DE- Declination sign
22- 23 I2 deg DEd Declination (J2000)
25- 26 I2 arcmin DEm Declination (J2000)
28- 32 F5.2 arcsec DEs Declination (J2000)
34- 40 A7 --- SpType Spectral type of the object
42- 51 A10 --- Obs ID of the observing program
53- 64 A12 --- UVB Name of the UVB spectrum file
in subdirectory fits
66- 77 A12 --- VIS Name of the VIS spectrum file
in subdirectory fits
79- 90 A12 --- NIR Name of the NIR spectrum file
in subdirectory fits
92- 94 I3 s tUVB Single exposure time for UVB spectrum
96- 98 I3 s tVIS Single exposure time for VIS spectrum
100-102 I3 s tNIR Single exposure time for NIR spectrum
104-106 F3.1 arcsec sUVB Width of the slit used for UVB spectrum
108-110 F3.1 arcsec sVIS Width of the slit used for VIS spectrum
112-114 F3.1 arcsec sNIR Width of the slit used for NIR spectrum
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Acknowledgements:
Laura Venuti, lvenuti27(at)gmail.com
(End) L. Venuti [NASA Ames Research Center], P. Vannier [CDS] 11-Oct-2019