J/AJ/146/39 Spectroscopy of NGC 5822-2 and NGC 5822-201 (Katime+, 2013)
Two barium stars in the open cluster NGC 5822.
Katime Santrich O.J., Pereira C.B., de Castro D.B.
<Astron. J., 146, 39 (2013)>
=2013AJ....146...39K 2013AJ....146...39K
ADC_Keywords: Clusters, open ; Stars, barium ; Equivalent widths
Keywords: open clusters and associations: individual: NGC 5822 -
stars: abundances - stars: fundamental parameters -
stars: individual (CPD -53 6222,CPD -53 6224)
Abstract:
Open clusters are very useful examples to explain the constraint of
the nucleosynthesis process with the luminosities of stars because the
distances of the clusters are better known than those of field stars.
We carried out a detailed spectroscopic analysis to derive the
chemical composition of two red giants in the young open cluster NGC
5822, NGC 5822-2, and NGC 5822-201. We obtained abundances of C, N, O,
Na, Mg, Al, Ca, Si, Ti, Ni, Cr, Y, Zr, La, Ce, and Nd. The atmospheric
parameters of the studied stars and their chemical abundances were
determined using high-resolution optical spectroscopy. We employed the
local thermodynamic equilibrium model atmospheres of Kurucz and the
spectral analysis code MOOG. The abundances of the light elements were
derived using the spectral synthesis technique. We found that NGC
5822-2 and -201 have, respectively, a mean overabundance of the
elements created by the s-process, "s," with the notation [s/Fe] of
0.77±0.12 and 0.83±0.05. These values are higher than those for
field giants of similar metallicity. We also found that NGC 5822-2 and
-201 have, respectively, luminosities of 140L☉ and 76L☉,
which are much lower than the luminosity of an asymptotic giant branch
star. We conclude that NGC 5822-2 and NGC 5822-201 are two new barium
stars first identified in the open cluster NGC 5822. The mass transfer
hypothesis is the best scenario to explain the observed
overabundances.
Description:
The high-resolution spectra for the two stars (NGC5822-2 and
NGC5822-201) were obtained at the 2.2m ESO telescope of La Silla,
Chile using the echelle spectrograph Fiberfed Extended Range Optical
Spectrograph (FEROS). The FEROS spectral resolving power is R=48000,
corresponding to 2.2pixels of 15µm, and has a complete wavelength
coverage without gaps from 3800Å to 9200Å.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 93 3 Log of the observations and other relevant
information for the target stars
table2.dat 37 98 Observed FeI and FeII lines
table3.dat 43 211 Other lines studied
refs.dat 243 18 References
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See also:
V/81 : Taxonomy of Barium Stars (Lu 1991)
I/108 : Cape Photographic Durchmusterung (Gill+ 1895-1900)
J/A+A/533/A51 : Abundances of 12 metal-rich barium stars (Pereira+, 2011)
J/A+A/515/A28 : Abundances of dwarfs & giants in 2 open clusters (Pace+, 2010)
J/A+A/502/267 : EWs of 31 giant stars of 10 open clusters (Smiljanic+, 2009)
J/A+A/485/303 : Radial velocities for 1309 stars & 166 OCl (Mermilliod+, 2008)
J/A+A/454/917 : Abundances of 26 barium stars. II. (Allen+, 2006)
J/AZh/81/658 : Equivalent widths of 9 barium stars (Antipova+, 2004)
J/AZh/80/704 : Studies of classical barium stars (Antipova+, 2003)
J/A+A/397/257 : Chemical compositions of four barium stars (Liang+, 2003)
J/AZh/79/909 : Chemical abundances in barium stars (Boyarchuk+, 2002)
J/A+A/319/881 : Ba II strength of barium stars (Gomez+ 1997)
J/PASP/105/78 : Photometry in open cluster NGC 5822 (Twarog+, 1993)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Star name (1)
14- 21 A8 --- CPD CPD identifier (1)
23- 27 F5.2 mag Vmag V-band magnitude (1)
29- 32 F4.2 mag B-V The B-V color index (1)
34- 39 F6.2 km/s RV1 Radial velocity (1)
41- 46 F6.2 km/s RV2 ? Radial velocity from our work
48- 51 F4.2 km/s e_RV2 ? Uncertainty in RV2
53- 62 A10 "date" Date ? Date of observation
64- 67 I4 s Exp ? Exposure time
69- 70 I2 h RAh Right ascension (ICRS), hours (2)
72- 73 I2 min RAm Right ascension (ICRS), minutes (2)
75- 80 F6.3 s RAs Right ascension (ICRS), seconds (2)
82 A1 --- DE- Declination (ICRS), sign (2)
83- 84 I2 deg DEd Declination (ICRS), degrees (2)
86- 87 I2 arcmin DEm Declination (ICRS), minutes (2)
89- 93 F5.2 arcsec DEs Declination (ICRS), seconds (2)
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Note (1): Taken from Mermilliod et al. (2008, cat. J/A+A/485/303).
Note (2): Position added at CDS, from Mermilliod 2008 (J/A+A/485/303) or Simbad.
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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- 5 A5 --- Ion Iron line identifier (FeI or FeII)
7- 13 F7.2 0.1nm lambda Wavelength; in Å
15- 18 F4.2 eV LEP Lower excitation potential of the transition
20- 25 F6.3 [-] loggf Log of the oscillator strength (1)
27- 29 I3 0.1pm EW2 ? Equivalent width for NGC 5822-2
31- 33 I3 0.1pm EW201 ? Equivalent width for NGC 5822-201
35- 37 I3 0.1pm EW65314 ? Equivalent width for HD 65314
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Note (1): The gf values for the FeI and FeII lines were taken from
Lambert et al. (1996ApJS..103..183L 1996ApJS..103..183L) and Castro et al.
(1997AJ....114..376C 1997AJ....114..376C).
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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- 7 F7.2 0.1nm lambda Wavelength; in Å
9- 13 A5 --- Ion Iron line identifier
15- 18 F4.2 eV LEP Lower excitation potential of the transition
20- 25 F6.3 [-] loggf Log of the oscillator strength
27- 31 A5 --- r_loggf Reference for loggf; in refs.dat file
33- 35 I3 0.1pm EW2 ? Equivalent width for NGC 5822-2
37- 39 I3 0.1pm EW201 ? Equivalent width for NGC 5822-201
41- 43 I3 0.1pm EW65314 ? Equivalent width for HD 65314
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Ref Reference number
7- 25 A19 --- BibCode Bibliographic code
27- 48 A22 --- Aut Author's name
50-243 A194 --- Com Comments
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History:
From electronic version of the journal
(End) Sylvain Guehenneux [CDS] 25-Jun-2014