J/ApJ/749/7 RVs and EWs of the binary BD+20 307 (Fekel+, 2012)
Third component search and abundances of the very dusty short-period binary
BD+20 307.
Fekel F.C., Cordero M.J., Galicher R., Zuckerman B., Melis C.,
Weinberger A.J.
<Astrophys. J., 749, 7 (2012)>
=2012ApJ...749....7F 2012ApJ...749....7F
ADC_Keywords: Equivalent widths ; Binaries, spectroscopic ; Radial velocities
Keywords: binaries: spectroscopic - stars: abundances -
stars: fundamental parameters - stars: individual: BD+20 307
Abstract:
We have obtained near-infrared adaptive optics imaging and collected
additional radial velocity observations to search for a third
component in the extremely dusty short-period binary system
BD +20° 307. Our image shows no evidence for a third component at
separations greater than 19 AU. Our four seasons of radial velocities
have a constant center-of-mass velocity and are consistent with the
systemic velocities determined at two earlier epochs. Thus, the radial
velocities also provide no support for a third component.
Unfortunately, the separation domains covered by our imaging and
radial velocity results do not overlap. Thus, we examined the
parameters for possible orbits of a third component that could have
been missed by our current observations. With our velocities we
determined improved circular orbital elements for the 3.4 day
double-lined binary. We also performed a spectroscopic abundance
analysis of the short-period binary components and conclude that the
stars are a mid- and a late-F dwarf. We find that the iron abundances
of both components, [Fe/H] = 0.15, are somewhat greater than the solar
value and comparable to that of stars in the Hyades. Despite the
similarity of the binary components, the lithium abundances of the two
stars are very unequal. The primary has log ε (Li) = 2.72,
while in the secondary log ε (Li) ≤ 1.46, which corresponds
to a difference of at least a factor of 18. The very disparate lithium
abundances in very similar stars make it impossible to ascribe a
single age to them. While the system is likely at least 1 Gyr old, it
may well be as old as the Sun.
Description:
On 2008 July 11, we obtained high angular resolution images of
BD +20 307 with the Keck II telescope of the Keck Observatory using
its AO system and the NIRC2 near-infrared narrow-field camera
in the Kp-bandpass, which is centered at 2.124um.
From 2008 January to 2011 January, we collected 64 usable observations
with the Tennessee State University 2m automatic spectroscopic
telescope (AST), fiber-fed echelle spectrograph, covering the
wavelength range 4920-7100Å and situated at Fairborn Observatory.
During 2008 and 2009, we acquired five red wavelength observations of
BD +20 307 with the Kitt Peak National Observatory (KPNO) coude feed
telescope.
In 2008, we obtained three echelle spectra at Lick Observatory with
the Shane 3 m telescope and Hamilton echelle spectrograph. The spectra
cover the wavelength range 3810-7900Å at a resolution of typically
0.17Å in the red region of the spectrum (resolving power 38000).
Objects:
-------------------------------------------------------
RA (2000) DE Designation(s)
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01 54 50.35 +21 18 22.5 BD +20 307 = TYC 1212-207-1
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 50 71 Radial velocities and orbital residuals
table5.dat 36 134 Equivalent widths
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See also:
V/136 : Teff and metallicities for Tycho-2 stars (Ammons+, 2006)
J/ApJ/745/147 : Binaries among debris disk stars (Rodriguez+, 2012)
J/ApJ/688/1345 : Differential phot. of the SB* BD+20 307 (Zuckerman+, 2008)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.3 d HJD [54495.5/55584.7] Heliocentric Julian Date;
HJD-2400000
11- 15 F5.3 --- Phase Phase
17- 21 F5.1 km/s RV1 [-56.4/30.7] Primary radial velocity
23- 26 F4.1 km/s O-C1 [-1.9/2.9] Primary orbital residual
28- 30 F3.1 --- W1 [0.2/1] Weight of primary
32- 36 F5.1 km/s RV2 [-60/34.8] Secondary radial velocity
38- 41 F4.1 km/s O-C2 [-2.1/3.2] Secondary orbital residual
43- 45 F3.1 --- W2 [0.2/0.6] Weight of secondary
47- 50 A4 --- Obs Observatory (1)
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Note (1): Observatory as follows:
Fair = Fairborn Observatory;
Lick = Lick Observatory;
KPNO = Kitt Peak National Observatory
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- Ion Chemical element and ionization stage
6- 12 F7.2 0.1nm lambda Wavelength; in Angstroms
14- 17 F4.2 eV ExPot Excitation potential
19- 23 F5.2 [-] log(gf) Log of the oscillator strength
25- 30 F6.2 0.1pm EW1 ? Corrected equivalent width of primary (mÅ)
32- 36 F5.1 0.1pm EW2 ? Corrected equivalent width of secondary (mÅ)
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 05-Nov-2013