J/A+A/552/A68 HD 261711 reduced spectrum (Zwintz+, 2013)
Regular frequency patterns in the young delta Scuti star HD 261711 observed by
the CoRoT and MOST satellites.
Zwintz K., Fossati L., Guenther D.B., Ryabchikova T., Baglin A.,
Themessl N., Barnes T.G., Matthews J.M., Auvergne M., Bohlender D.,
Chaintreuil S., Kuschnig R., Moffat A.F.J., Rowe J.F., Rucinski S.M.,
Sasselov D., Weiss W.W.
<Astron. Astrophys. 552, A68 (2013)>
=2013A&A...552A..68Z 2013A&A...552A..68Z
ADC_Keywords: Spectroscopy ; Stars, A-type ; Stars, pre-main sequence ;
Stars, variable
Keywords: stars: variables: delta Scuti - stars: oscillations -
stars: individual: HD 261711 - techniques: photometric -
techniques: spectroscopic
Abstract:
The internal structure of pre-main-sequence (PMS) stars is poorly
constrained at present. This could change significantly through
high-quality asteroseismological observations of a sample of such
stars.
We concentrate on an asteroseismological study of HD 261711, a rather
hot delta Scuti-type pulsating member of the young open cluster NGC
2264 located at the blue border of the instability region. HD 261711
was discovered to be a pre-main sequence delta Scuti star using the
time series photometry obtained by the MOST satellite in 2006.
High-precision, time-series photometry of HD 261711 was obtained by
the MOST and CoRoT satellites in four separate new observing runs that
are put into context with the star's fundamental atmospheric
parameters obtained from spectroscopy. Frequency Analysis was
performed using Period04. The spectral analysis was performed using
equivalent widths and spectral synthesis.
With the new MOST data set from 2011/12 and the two CoRoT light curves
from 2008 and 2011/12, the delta Scuti variability was confirmed and
regular groups of frequencies were discovered. The two pulsation
frequencies identified in the data from the first MOST observing run
in 2006 are confirmed and 23 new delta Scuti-type frequencies were
discovered using the CoRoT data. Weighted average frequencies for each
group were determined and are related to l=0 and l=1 p-modes. Evidence
for amplitude modulation of the frequencies in two groups is seen. The
effective temperature (Teff) was derived to be 8600±200K, logg is
4.1±0.2, and the projected rotational velocity (vsini) is
53±1km/s. Using our Teff value and the radius of 1.8±0.5R☉
derived from spectral energy distribution (SED) fitting, we get a
luminosity logL/L☉ of 1.20±0.14 which agrees well to the
seismologically determined values of 1.65 Rsun and, hence, a
logL/L☉ of 1.13. The radial velocity of 14±2km/s we derived
for HD 261711, confirms the star's membership to NGC 2264.
Our asteroseismic models suggest that HD 261711 is a delta Scuti-type
star close to the zero-age main sequence (ZAMS) with a mass of 1.8 to
1.9M☉. With an age of about 10 million years derived from
asteroseismology, the star is either a young ZAMS star or a late PMS
star just before the onset of hydrogen-core burning. The observed
splittings about the l=0 and 1 parent modes may be an artifact of
the Fourier derived spectrum of frequencies with varying amplitudes.
Description:
Spectrum for HD 261711 with resolution R∼52000 obtained with the
Robert G. Tull Coude spectrograph at the 2.7m telescope of Mc Donald
Observatory, Texas. The spectrum was obtained on Dec 20, 2010, and
covers the 3928 to 9926Å wavelength range with gaps between the
echelle orders at wavelengths longer than 5880Å. The exposure time
was 90 minutes. The signal-to-noise ratio per pixel calculated over
1Å at ∼5000Å is about 100.
Objects:
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RA (2000) DE Designation(s)
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06 40 16.19 +09 17 13.1 HD 261711 = 2MASS J06401619+0917130
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
hd261711.dat 19 97712 HD 261711 spectrum
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Byte-by-byte Description of file: hd261711.dat
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Bytes Format Units Label Explanations
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1- 10 F10.5 0.1nm lambda [3928/9927] Wavelength in Angstroms
11- 19 F9.6 --- Flux Normalized flux
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Acknowledgements:
Konstanze Zwintz, konstanze.zwintz(at)ster.kuleuven.be
(End) Konstanze Zwintz [KU Leuven, Belgium], Patricia Vannier [CDS] 26-Feb-2013