J/AJ/132/1714 Photometric and Spectroscopic study of TY Gru (Preston+, 2006)
TY Gruis: a metal-poor carbon and neutron-capture-rich RR Lyrae star.
Preston G.W., Thompson I.B., Sneden C., Stachowski G., Shectman S.A.
<Astron. J., 132, 1714-1724 (2006)>
=2006AJ....132.1714P 2006AJ....132.1714P
ADC_Keywords: Stars, variable ; Photometry ; Equivalent widths ;
Radial velocities
Keywords: stars: abundances - stars: horizontal-branch -
stars: individual (TY Gruis) - stars: Population II -
stars: variables: other
Abstract:
We have conducted a photometric and high-resolution spectroscopic
analysis of the high-latitude (l=1°, b=-55°) metal-poor RR Lyrae
star TY Gru (=CS 22881-071). We find this star to have large
overabundances of carbon and neutron-capture elements. Mass transfer
from an asymptotic giant branch binary companion prior to its RR Lyrae
evolutionary state is the simplest explanation of this circumstance.
Unfortunately, TY Gru is afflicted by the Blazhko effect, which
greatly complicates accurate measurement of the motion of its center
of mass. We have not yet detected the small orbital motion that would
be produced by a distant degenerate companion of TY Gru.
Description:
V-band CCD observations made at the Las Campanas Observatory (LCO) 1m
Swope telescope.
We made spectroscopic observations with the Clay 6.5m MIKE
(R=λ/Δλ∼40000) and du Pont 2.5m echelle (R∼25000)
spectrographs. Properties of the two spectrographs are presented at
the LCO Web site (http://www.lco.cl)
Objects:
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RA (2000) DE Designation(s)
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22 16 39.4 -39 56 18 TY Gru = V* TY Gru
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 19 110 Photometry
table2.dat 32 80 Spectroscopic Observations
table4.dat 36 193 Line Data
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 12 F12.4 d HJD Heliocentric Julian Date of observation
14- 19 F6.3 mag Vmag The TY Gru V band magnitude
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Tel The Telescope/observer code (1)
10- 21 F12.4 d HJD Heliocentric Julian Date of observation
23- 26 F4.2 --- Phase Pulsation phase (P=0.570065)
28- 32 F5.1 km/s RV Radial velocity
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Note (1): Telescope/observer code as follows:
MIKE = Magellan Clay MIKE spectrograph
duP = du Pont 2.5-m echelle spectrograph
gwp = G.W. Preston
ibt = I.B. Thompson
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 7 F7.2 0.1nm lambda Wavelength in Angstroms
9- 13 A5 --- Ion Ion species
15- 18 F4.2 eV ExPot Excitation potential
20- 24 F5.2 [-] log(gf) Log of the oscillator strength
26- 28 I3 0.1pm EW ? Equivalent width in mÅ (1)
29 A1 --- u_EW Uncertainty flag on EW (1)
31 A1 --- f_EW [s] Synthesis flag on EW (1)
33- 36 F4.2 [-] log(e) Log of the abundance
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Note (1):
* An equivalent width without uncertainty or synthesis flags means
that it was used in a single-line analysis.
* Equivalent widths with just a synthesis flag indicates
multiple-component analysis.
* Equivalent widths with both uncertainty and synthesis flags are cases
where spectrum synthesis was used, and the equivalent widths are given
only as a rough guide to the feature strength.
* A blank equivalent width with a synthesis flag means that spectrum
synthesis was used, and no meaningful EW could be quoted.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 11-Jul-2008