J/ApJ/848/68 Abundances & RVs of stable and Blazhko RRc stars (Sneden+, 2017)
The RRc stars: chemical abundances and envelope kinematics.
Sneden C., Preston G.W., Chadid M., Adamow M.
<Astrophys. J., 848, 68-68 (2017)>
=2017ApJ...848...68S 2017ApJ...848...68S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable; Radial velocities; Abundances; Optical
Keywords: methods: observational; stars: abundances; stars: atmospheres;
stars: variables: RR Lyrae; techniques: spectroscopic
Abstract:
We analyzed series of spectra obtained for 12 stable RRc stars
observed with the echelle spectrograph of the du Pont telescope at Las
Campanas Observatory and we analyzed the spectra of RRc Blazhko stars
discussed by Govea+ (2014, J/ApJ/782/59). We derived model atmosphere
parameters, [Fe/H] metallicities, and [X/Fe] abundance ratios for 12
species of 9 elements. We co-added all spectra obtained during the
pulsation cycles to increase signal to noise and demonstrate that
these spectra give results superior to those obtained by co-addition
in small phase intervals. The RRc abundances are in good agreement
with those derived for the RRab stars of Chadid+
(2017ApJ...835..187C 2017ApJ...835..187C). We used radial velocity (RV) measurements of
metal lines and Hα to construct variations of velocity with
phase, and center-of-mass velocities. We used these to construct RV
templates for use in low- to medium-resolution RV surveys of RRc
stars. Additionally, we calculated primary accelerations, radius
variations, and metal and Hα velocity amplitudes, which we
display as regressions against primary acceleration. We employ these
results to compare the atmosphere structures of metal-poor RRc stars
with their RRab counterparts. Finally, we use the RV data for our
Blazhko stars and the Blazhko periods of Szczygiel & Fabrycky (2007,
J/MNRAS/377/1263) to falsify the Blazhko oblique rotator hypothesis.
Description:
The Las Campanas Observatory (LCO) 2.5m du Pont echelle spectrograph
was employed with a resolving power R∼27000 at 5000Å (spectral
domain λλ∼3400-9000Å).
A total of 615 echelle observations were obtained during 6 nights in
2014 March and 3 nights in 2014 September. Complete or almost complete
phase coverage of the pulsation cycles was achieved for 7 of the 12
stable RRc stars from ASAS (II/264).
Observations of the 7 Blazhko RRc stars discussed previously by Govea+
(2014, J/ApJ/782/59) were obtained in 2009 and 2010, as circumstances
permitted during our RRab survey (Chadid+, 2017ApJ...835..187C 2017ApJ...835..187C).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 75 19 RR Lyrae program star data
table2.dat 58 633 Radial velocities
table4.dat 96 131 Stellar parameters from phased-averaged spectra
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See also:
II/264 : ASAS Variable Stars in Southern hemisphere (Pojmanski+, 2002-2005)
J/ApJS/219/25 : LCs of RR Lyrae stars in M3 (NGC5272) (Jurcsik+, 2015)
J/AcA/64/177 : VI light curves of Galactic Bulge RR Lyrae (Soszynski+, 2014)
J/ApJS/213/9 : Catalina Surveys periodic variable stars (Drake+, 2014)
J/ApJ/782/59 : Abundances of 8 RR Lyrae subclass C stars (Govea+, 2014)
J/MNRAS/427/3374 : QUEST RR Lyrae Survey III. Low Galactic lat. (Mateu+, 2012)
J/AJ/144/114 : Radial velocities of 6 field RR Lyrae (Sesar+, 2012)
J/ApJS/197/29 : Chemical compositions of 11 RR Lyrae (For+, 2011)
J/ApJS/194/38 : Radial velocities of 11 field RR Lyrae (For+, 2011)
J/MNRAS/377/1263 : Multiperiodic RR Lyrae in ASAS catalog (Szczygiel+, 2007)
J/MNRAS/372/69 : VR light curves of M2 variables (Lazaro+, 2006)
J/A+A/330/515 : RR Lyrae parallaxes + proper motions (Fernley+ 1998)
J/A+AS/125/313 : RR Lyrae radial velocities and [Fe/H] I. (Fernley+ 1997)
J/A+AS/125/321 : RR Lyrae radial velocities and [Fe/H] II. (Solano+ 1997)
J/AJ/110/1186 : SX Phe stars in NGC 5053 (Nemec+ 1995)
J/AJ/108/1016 : Kinematics of local RR lyrae stars. I. (Layden, 1994)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1 I1 --- RRc RRc sample, 1:Stable RRc, 2: Blazhko RRc
3- 15 A13 --- ASAS All Sky Automated identifier,
HHMMSS+DDMM.m (J2000), Pojmanski (2003, II/264)
17- 24 A8 --- Name Shortened ASAS name used in text and
other tables
26- 35 A10 --- OName Other Name
37- 41 F5.2 [Sun] [Fe/H] [-2.7/-0.9] Mean metallicity (1)
43- 50 F8.6 d Per [0.2/0.4] Period (2)
52- 59 F8.3 d HJD0 Epoch of light minimum, HJD-2450000 (2)
61- 65 F5.2 mag Vmin [8.7/12.8] V band brightness at minimum
67- 70 F4.2 mag Vamp Amplitude of V band variation
72- 75 F4.1 km/s RVamp ? Radial velocity amplitude of metal lines
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Note (1): Mean of Table 6 entries for neutral and ionized Fe species
Note (2): For the Period the source is ASAS for the stable RRc stars, and
Govea+ (2014, J/ApJ/782/59) for the Blazhko stars; for HJD0 the
source is this study for the stable stars, and Govea+
(2014, J/ApJ/782/59) for the Blazhko stars.
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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 --- Name Abbreviated ASAS star name
9- 20 A12 --- File Observed file name
21- 33 F13.4 d HJD Heliocentric Julian Date; HJD-2450000
34- 40 F7.3 --- phi Pulsational phase
44- 49 F6.1 km/s RVm [-162.4/226.3] Radial velocity of the metal lines
53- 58 F6.1 km/s RVHa [-178.1/235.7] Radial velocity of Hα
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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- 8 A8 --- Name Abbreviated ASAS star name
9- 19 F11.3 --- phi Pulsational phase of observation
20- 26 I7 --- Nsp [2/15] Number of spectra co-added at this phase
27- 33 I7 K Teff [6550/7800] Effective temperature
34- 40 F7.2 [cm/s2] log(g) [1.6/4] Logarithm of surface gravity
41- 47 F7.2 [Sun] [M/H] [-2.8/2.6] Metallicity of the model atmosphere
48- 54 F7.1 km/s xi [1/3.5] Microturbulent velocity
55- 61 F7.2 [Sun] [Fe/H]I [-3/-0.9] Fe I abundance
62- 68 F7.2 [Sun] e_[Fe/H]I [0.1/0.6] Sample standard deviation
for Fe I abundance
69- 75 I7 --- o_[Fe/H]I [6/113] Number of lines contributing
to FeI abundance
76- 82 F7.2 [Sun] [Fe/H]II [-3/-0.9] Fe II abundance
83- 89 F7.2 [Sun] e_[Fe/H]II [0.1/0.5] Sample standard deviation
for FeII abundance
90- 96 I7 --- o_[Fe/H]II [3/39] Number of lines contributing
to FeII abundance
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 11-Jun-2018