J/MNRAS/447/2404 Equivalent width of 21 RR Lyrae stars (Pancino+, 2015)
Chemical abundances of solar neighbourhood RR Lyrae stars.
Pancino E., Britavskiy N., Romano D., Cacciari C., Mucciarelli A.,
Clementini G.
<Mon. Not. R. Astron. Soc. 447, 2404 (2015)>
=2015MNRAS.447.2404P 2015MNRAS.447.2404P
ADC_Keywords: Stars, nearby ; Stars, variable ; Spectroscopy ; Equivalent widths
Keywords: stars: abundances - stars: variables: Cepheids -
stars: variables: general - stars: variables: RR Lyrae
Abstract:
We have analysed a sample of 18 RR Lyrae stars (17 fundamental-mode -
RRab - and one first overtone - RRc) and three Population II Cepheids
(two BL Her stars and one W Vir star), for which high-resolution
(R≥30000), high signal-to-noise (S/N≥30) spectra were obtained with
either SARG at the Telescopio Nazionale Galileo (La Palma, Spain) or
UVES at the ESO Very Large Telescope (Paranal, Chile). Archival data
were also analyzed for a few stars, sampling ≳3 phases for each star.
We obtained atmospheric parameters (Teff, logg, vt, and [M/H]) and
abundances of several iron-peak and α-elements (Fe, Cr, Ni, Mg,
Ca, Si, and Ti) for different pulsational phases, obtaining
<[α/Fe]≥+0.31±0.19dex over the entire sample covering
-2.2<[Fe/H]←1.1dex. We find that silicon is indeed extremely
sensitive to the phase, as reported by previous authors, and cannot be
reliably determined. Apart from this, metallicities and abundance
ratios are consistently determined, regardless of the phase, within
0.10-0.15 dex, although caution should be used in the range
0≲φ≲0.15. Our results agree with literature determinations for
both variable and non-variable field stars, obtained with very
different methods, including low and high-resolution spectroscopy. W
Vir and BL Her stars, at least in the sampled phases, appear
indistinguishable from RRab from the spectroscopic analysis point of
view. Our large sample, covering all pulsation phases, confirms that
chemical abundances can be obtained for RR Lyrae with the classical
EW-based technique and static model atmospheres, even rather close to
the shock phases.
Description:
Equivalent widths and atomic data of the absorption lines used in the
abundance analysis, for each separate exposure at different phases.
Observations of 15 RR Lyrae stars (DR And, X Ari, TW Boo, RZ Cam, RX
Cet, U Com, RV CrB, SW CVn, UZ CVn, AE Dra, SZ Gem, VX Her, DH Hya, TU
UMa, and RV UMa) and one BL Her star (UY Eri) were carried out with
SARG@TNG, operated on the island of La Palma, Spain, during two
separate runs in 2009 March and between September and November.
Eight stars (SW Aqr, TW Cap, DH Hya, V Ind, SS Leo, V716 Oph, BK Tuc,
and UV Vir) were observed with UVES@VLT, between 2009 April and August
in service mode.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 106 21 Basic information for the programme stars
table2.dat 45 59 Observing logs
table4.dat 66 8546 Equivalent wodths and atomic data for individual
program stars spectra
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Star Star name
9 A1 --- n_Star [*] Note on Star (2)
11- 12 I2 h RAh Right ascension (J2000) (1)
14- 15 I2 min RAm Right ascension (J2000) (1)
17- 21 F5.2 s RAs Right ascension (J2000) (1)
23 A1 --- DE- Declination (J2000) (1)
24- 25 I2 deg DEd Declination (J2000) (1)
27- 28 I2 arcmin DEm Declination (J2000) (1)
30- 33 F4.1 arcsec DEs Declination (J2000)
35- 38 A4 --- Type Variable type (1)
40- 46 A7 --- Type2 Alternative variable type (1)
48- 52 F5.2 mag Vmin [8.9/12.4] Minimum value of V magnitude (1)
53 A1 --- --- [-]
54- 58 F5.2 mag Vmax [9.9/13.4] Maximum value of V magnitude (1)
60- 71 F12.6 d T0 Epoch of maximum light (JD-2400000) (3)
73- 83 F11.8 d Per Period
85- 88 F4.2 mag AV Absorption in V band
89 A1 --- n_AV [)] Origin of AV (4)
91- 95 F5.2 [Sun] [Fe/H]1 [-2.5/-0.8]?=- Metallicity from
Kinemuchi et al. 2006 (J/AJ/132/1202) (5)
97-100 F4.2 [Sun] e_[Fe/H]1 ? rms uncertainty on [Fe/H]K06
102-106 F5.2 [Sun] [Fe/H]2 [-2.5/-0.8] Metallicity from Beers et al.
(2000, Cat. J/AJ/119/2866) (5)
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Note (1): Coordinates, type of variability, rough magnitude ranges and adopted
periods are from the General Catalogue of Variable Stars (GCVS; Samus et al.
2010, Cat. B/gcvs), except for X Ari, TW Boo, RX Cet, and VX Her, that are
known to have a variable period (Le Borgne et al. 2007A&A...476..307L 2007A&A...476..307L,
Cat. J/A+A/476/307, see also text).
Note (2): * indicates stars that do not have a clear classification, but for our
computations we used the type in Type.
Note (3): Epochs of maximum light have been derived by us from ROTSE light
curves, except for X Ari, TW Boo, RX Cet, and VX Her, where a parabolic fit
was used, based on data from Le Borgne et al. (2007, Cat. J/A+A/476/307,).
For a few stars with no ROTSE data, epochs are taken from the GCVS, and for
SS Leo from Maintz (2005A&A...442..381M 2005A&A...442..381M, Cat. J/A+A/442/381).
V amplitudes are from Kinemuchi et al. (2006AJ....132.1202K 2006AJ....132.1202K,
Cat. J/AJ/132/1202);
Note (4): ) indicates that AV are either derived from ROTSE light curves
(TW Cap, U Com, UY Eri, and V716 Oph), or taken from the ASAS-3 catalogue
(V Ind, VW Scl, BK Tuc; Pojmanski, 1997AcA....47..467P 1997AcA....47..467P);
Note (5): typical errors are on the order 0.1-0.2dex.
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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 --- Star Star name
10- 14 A5 --- Inst Instrument
17- 18 I2 --- Exp [1/10] Exposure number for star+instrument
19 A1 --- n_Exp [*] * indicates archival spectra
21- 31 F11.5 d ObsDate Observation date (HJD-2400000)
33- 36 F4.2 --- Phase [0/1] Phase
38- 41 F4.1 min texp [3/60] Exposure time
43- 45 I3 --- S/N [20/160] Signal-to-noise ratio (at 600nm)
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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 --- Star Star name
10- 15 A6 --- Inst Instrument name
16 I1 --- Exp [0/9] Exposure number for star+instrument
17- 26 F10.3 0.1nm lambda [4620/7946] Wavelength λ in Angstroms
30- 34 A5 --- Ion Element name and ionization stage
35- 42 F8.2 0.1pm EW [6/111] Equivalent width in milliAngstroms
43- 49 F7.2 0.1pm e_EW Error on EW in milliAngstroms
50- 58 F9.3 [-] loggf Logarithm of the oscillator strength
59- 66 F8.3 eV EP Excitation potential χ
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Acknowledgements:
Elena Pancino, elena.pancino(at)oabo.inaf.it
(End) Elena Pancino [INAF-OABo, Italy], Patricia Vannier [CDS] 26-Feb-2015