J/AJ/155/240 A spectroscopic survey of field RHB stars (Afsar+, 2018)
A spectroscopic survey of field red horizontal-branch stars.
Afsar M., Bozkurt Z., Topcu G.B., Casetti-Dinescu D.I., Sneden C.,
Sehitoglu G.
<Astron. J., 155, 240 (2018)>
=2018AJ....155..240A 2018AJ....155..240A (SIMBAD/NED BibCode)
ADC_Keywords: Stars, nearby ; Stars, horizontal branch ; Spectroscopy ;
Parallaxes, trigonometric ; Radial velocities ; Space velocities ;
Effective temperatures ; Abundances ; Stars, distances
Keywords: stars: abundances - stars: atmospheres - stars: evolution -
stars: horizontal-branch
Abstract:
A metallicity, chemical composition, and kinematic survey has been
conducted for a sample of 340 candidate field red horizontal-branch (RHB)
stars. Spectra with high resolution and high signal-to-noise ratio were
gathered with the McDonald Observatory 2.7 m Tull and the Hobby-Eberly
Telescope echelle spectrographs, and were used to determine effective
temperatures, surface gravities, microturbulent velocities, [Fe/H]
metallicities, and abundance ratios [X/Fe] for seven α and Fe-group
species. The derived temperatures and gravities confirm that at least
half of the candidates are true RHB stars, with (average) parameters
Teff∼5000 K and log g∼2.5. From the α abundances alone, the thin
and thick Galactic populations are apparent in our sample. Space motions
for 90% of the program stars were computed from Hipparcos and Gaia
parallaxes and proper motions. Correlations between chemical compositions
and Galactic kinematics clearly indicate the existence of both thin-disk
and thick-disk RHB stars.
Description:
From 2011 to 2014 we obtained high-resolution spectra with high
signal-to-noise ratios (S/N) of our program stars with echelle
spectrographs of two telescopes located at McDonald Observatory.
For the majority of targets we employed the 2.7 m HJS and its Robert
G. Tull Cross-Dispersed Echelle spectrograph (Tull et al.
1995PASP..107..251T 1995PASP..107..251T). Data were acquired in several observing runs
dedicated to this program. The instrumental setup was identical to that
used by Afsar et al. (2012AJ....144...20A 2012AJ....144...20A). Briefly, the combination of
echelle grating, camera, and a 1.2" width entrance slit yielded a spectral
resolving power of R=λ/Δλ∼60000. The total wavelength
coverage was λλ3400-10900, encompassing 63 echelle spectral
orders.
For some targets we employed the 9.2 m HET and its High Resolution
Spectrograph (HRS; Tull 1998SPIE.3355..387T 1998SPIE.3355..387T). These data were obtained in
queue observing mode by the HET staff in individual time slots that
depended on the larger HET scheduling matrix, rather than on specifically
scheduled nights. The instrumental setup was identical to that used by
Bocek Topcu et al. (2016, J/MNRAS/463/580). There are two CCD detectors in
this instrument to achieve large spectral coverage. The wavelength ranges
were 5100-6900 Å on the "blue" detector and 7000-8800 Å on the "red"
detector. The spectral resolving power was R sime 60000.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 97 340 Basic program star data
table2.dat 94 315 Parallaxes and velocities
table3.dat 97 346 Model atmospheric parameters
table5.dat 113 346 Elemental abundances
table6.dat 102 305 Galactic orbital parameters
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See also:
I/311 : Hipparcos, the New Reduction (van Leeuwen, 2007)
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
J/MNRAS/371/703 : MILES library of empirical spectra (Sanchez-Blazquez+, 2006)
J/AJ/140/500 : Kimematics of horizontal-branch stars from SDDSS-DR7
(Chen+, 2010)
J/AJ/140/1694 : Abundances of non-variable red and blue HB stars (For+, 2010)
J/MNRAS/411/435 : Stellar parameters and extinction (Bailer-Jones, 2011)
J/PASJ/63/1035 : Stellar parameters and abundances of 99 giants (Wang+, 2011)
J/ApJ/751/130 : SDSS-DR7 red HB stars spectroscopic data (Shi+, 2012)
J/A+A/574/A50 : Chemical abundances of giants and subgiants (Jofre+, 2015)
J/MNRAS/463/580 : Abundances of red giants in NGC6940 (Bocek+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Star Star name (1)
19- 20 I2 h RAh Simbad Hour of Right Ascension (J2000)
22- 23 I2 min RAm Simbad Minute of Right Ascension (J2000)
25- 30 F6.3 s RAs Simbad Second of Right Ascension (J2000)
32 A1 --- DE- Simbad Sign of the Declination (J2000)
33- 34 I2 deg DEd Simbad Degree of Declination (J2000)
36- 37 I2 arcmin DEm Simbad Arcminute of Declination (J2000)
39- 43 F5.2 arcsec DEs Simbad Arcsecond of Declination (J2000)
45- 49 F5.2 mag Bmag [4.32/14.9]? Simbad B band magnitude
51- 55 F5.2 mag Vmag [3.41/13.81] Simbad V band magnitude
57- 61 F5.2 mag Kmag [0.8/11.72]? Simbad K band magnitude
63- 66 F4.2 mag Av [0/2.08]? Interstellar extinction
68- 69 I2 --- r_Av [1/11]? Reference for Av (2)
71- 74 F4.2 mag E(B-V) [0/0.67]? Color excess (3)
76- 87 A12 --- SpType Simbad MK spectral type
89- 97 A9 --- Inst Telescope/Instrument (4)
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Note (1): Star name taken as available from HIP number preferably, then BD
number, then GSC number.
Note (2): Reference as follows:
1 = Bailer-Jones (2011, J/MNRAS/411/435);
2 = Jofre et al. (2015, J/A+A/574/A50);
3 = Straizys et al. (2005BaltA..14..555S 2005BaltA..14..555S);
4 = Liu et al. (2010PASJ...62.1071L 2010PASJ...62.1071L);
5 = Takeda et al. (2008PASJ...60..781T 2008PASJ...60..781T);
6 = Matrozis et al. (2013A&A...559A.115M 2013A&A...559A.115M);
7 = Goswami & Karinkuzhi (2013A&A...549A..68G 2013A&A...549A..68G);
8 = Wang et al. (2011, J/PASJ/63/1035);
9 = Cruzalebes et al. (2013MNRAS.434..437C 2013MNRAS.434..437C);
10 = Sanchez-Blazquez et al. (2006, J/MNRAS/371/703);
11 = Huber et al. (2012ApJ...760...32H 2012ApJ...760...32H).
Note (3): E(B-V)=AV/3.1.
Note (4): Instrument as follows:
2.7m/Tull = McDonald 2.7m telescope and Tull et al. (1995PASP..107..251T 1995PASP..107..251T)
echelle spectrograph;
HET/HRS = Hobby-Eberly Telescope and Tull (1998SPIE.3355..387T 1998SPIE.3355..387T) echelle
spectrograph.
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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- 17 A17 --- Star Star name
19- 23 F5.2 mas PlxH [-0.8/32.48]? HIPPARCOS parallax
25- 28 F4.2 mas e_PlxH [0.1/4.12]? HIPPARCOS parallax error
30- 34 F5.2 mas PlxG [0.46/22.41]? GAIA parallax
36- 39 F4.2 mas e_PlxG [0.21/0.97]? GAIA parallax error
41- 47 F7.2 km/s RV [-197.13/169.7] Radial velocity
49- 52 F4.2 km/s e_RV [0.1/1.9] Radial velocity error
54- 60 F7.2 km/s U-LSR [-303.01/273.91] Space velocity ULSR
62- 66 F5.2 km/s e_U-LSR [0.03/46.77] Standard deviation of U-LSR
68- 74 F7.2 km/s V-LSR [-374.61/47.09] Space velocity VLSR
76- 80 F5.2 km/s e_V-LSR [0.07/77.04] Standard deviation of V-LSR
82- 88 F7.2 km/s W-LSR [-170.24/85.09] Space velocity WLSR
90- 94 F5.2 km/s e_W-LSR [0.02/41.93] Standard deviation of W-LSR
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Star Star name
19- 22 I4 K Teff(B-V) [140/9481]? (B-V) color temperature
24- 27 I4 K Teff(V-K) [4020/7413]? (V-K) color temperature
29- 32 I4 K Teff(LDR) [4232/5521]? (LDR) temperature
34- 37 F4.2 [cm/s2] loggH [1.18/5.73]? Surface gravity calculated
using HIPPARCOS parallax
39- 42 F4.2 [cm/s2] loggG [1.48/4.59]? Surface gravity calculated
using GAIA parallax
44- 47 I4 K Teff(sp) [3935/6103] Spectral temperature
49- 52 F4.2 [cm/s2] logg(sp) [0.59/4.69] Surface gravity from spectral
analysis
54- 58 F5.2 --- [M/H] [-2.1/0.26] Metallicity estimate from
neutral and ionized Fe and Ti lines
60- 63 F4.2 km/s Vt [0.17/2.06] Microturbulent velocity ξt
65- 69 F5.2 --- [FeI/H] [-2.02/0.43] Metallicity estimate from
neutral Fe lines
71- 74 F4.2 --- e_[FeI/H] [0.05/0.08] Standard deviation of [FeI/H]
measurements
76- 77 I2 --- o_[FeI/H] [32/69] Number of lines used in [FeI/H]
estimate
79- 83 F5.2 --- [FeII/H] [-2.07/0.36] Metallicity estimate from
ionized Fe lines
85- 88 F4.2 --- e_[FeII/H] [0/0.17] Standard deviation of [FeII/H]
measurements
90- 91 I2 --- o_[FeII/H] [1/12] Number of lines used in [FeII/H]
estimate
93- 97 F5.2 --- [Fe/H] [-2.05/0.38] Average metallicity from
[FeI/H] and [FeII/H]
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Star Star name
19- 23 F5.2 --- [Si/Fe] [-0.05/0.5] Derived [Si/Fe] abundance
25- 28 F4.2 --- e_[Si/Fe] [0.03/0.1] Standard deviation of [Si/Fe]
30- 31 I2 --- o_[Si/Fe] [5/17] Number of lines used in [Si/Fe]
estimate
33- 37 F5.2 --- [Ca/Fe] [-0.15/0.41] Derived [Ca/Fe] abundance
39- 42 F4.2 --- e_[Ca/Fe] [0.03/0.09] Standard deviation of [Ca/Fe]
44- 45 I2 --- o_[Ca/Fe] [4/11] Number of lines used in [Ca/Fe]
estimate
47- 51 F5.2 --- [TiI/Fe] [-0.22/0.4] Derived [TiI/Fe] abundance
53- 56 F4.2 --- e_[TiI/Fe] [0/0.13] Standard deviation of [TiI/Fe]
58- 59 I2 --- o_[TiI/Fe] [1/11] Number of lines used in [TiI/Fe]
estimate
61- 65 F5.2 --- [TiII/Fe] [-0.33/0.42] Derived [TiII/Fe] abundance
67- 70 F4.2 --- e_[TiII/Fe] [0/0.64] Standard deviation of [TiII/Fe]
72- 72 I1 --- o_[TiII/Fe] [1/6] Number of lines used in [TiII/Fe]
estimate
74- 78 F5.2 --- [CrI/Fe] [-0.26/0.1] Derived [CrI/Fe] abundance
80- 83 F4.2 --- e_[CrI/Fe] [0/0.2] Standard deviation of [CrI/Fe]
85- 86 I2 --- o_[CrI/Fe] [1/19] Number of lines used in [CrI/Fe]
estimate
88- 92 F5.2 --- [CrII/Fe] [-0.23/0.34]? Derived [CrII/Fe] abundance
94- 97 F4.2 --- e_[CrII/Fe] [0/0.3]? Standard deviation of [CrII/Fe]
99- 99 I1 --- o_[CrII/Fe] [0/5] Number of lines used in [CrII/Fe]
estimate
101-105 F5.2 --- [NiI/Fe] [-0.17/0.19] Derived [NiI/Fe] abundance
107-110 F4.2 --- e_[NiI/Fe] [0.01/0.09] Standard deviation of [NiI/Fe]
112-113 I2 --- o_[NiI/Fe] [7/28] Number of lines used in [NiI/Fe]
estimate
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Star Star name
19- 25 F7.1 kpc.km/s Lz [-1264.8/2165.1] z-component of the angular
momentum
27- 31 F5.1 kpc.km/s E_Lz [0.6/466.9] Upper error in Lz
33- 38 F6.1 kpc.km/s e_Lz [-869/-0.6] Lower error in Lz
40- 48 F9.1 km2/s2 Etot [-100602.4/-43813.5] Total orbital energy
50- 56 F7.1 km2/s2 E_Etot [10.4/83117.3] Upper error in Etot
58- 65 F8.1 km2/s2 e_Etot [-11794.6/-10.9] Lower error in Etot
67- 71 F5.2 kpc Rm [4.06/13.74] Mean Galactocentric distance
73- 77 F5.2 kpc E_Rm [0/13.51] Upper error in Rm
79- 83 F5.2 kpc e_Rm [-4.89/0] Lower error in Rm
85- 89 F5.3 --- e [0.01/0.867] Orbital eccentricity
91- 95 F5.3 --- E_e [0/0.381] Upper error in e
97-102 F6.3 --- e_e [-0.255/0] Lower error in e
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 17-Dec-2018