J/ApJ/479/427 Abundance Analyses of RV Tauri Variables (Gonzalez+ 1997)
Abundance Analyses of the Field RV Tauri Variables: EP Lyrae, DY Orionis,
AR Puppis, and R Sagittae
Gonzalez G., Lambert D.L., Giridhar S.
<Astrophys. J. 479, 427 (1997)>
=1997ApJ...479..427G 1997ApJ...479..427G
ADC_Keywords: Stars, variable ; Abundances ; Stars, horizontal branch
Keywords: stars: abundances - stars: AGB and post-AGB -
stars: variables: other (RV Tauri)
Abstract:
Analyses of the photospheric compositions of the four field RV Tauri
stars, EP Lyr, DY Ori, AR Pup, and R Sge, indicate that to varying
degrees they have experienced fractionation processes that have
preferentially depleted their atmospheres of elements with high
condensation temperatures. The depletion, as indicated by, for
instance, [S/Fe], is greatest for DY Ori, [S/Fe]=2.5, and least for
R Sge, [S/Fe]=0.9. The initial composition, presumably indicated by
the sulfur abundance, was nearly solar for AR Pup, R Sge, and DY Ori,
while it was about 0.6--- less than solar for EP Lyr. This implies
that the RV Tauri stars as a group may not be as metal-poor as
previously thought---they are instead ``metal-depleted''. The field RV
Tauri's are not halo stars, but probably belong to the thick disk.
This brings to seven the number of type II Cepheids that show such a
trend; the other three are IW Car and V1 in omega Cen, RV Tauri stars,
and ST Pup, a W Virginis star. The 12C/13C ratios for EP Lyr and DY
Ori are 9±1 and 6±3, respectively, indicating that CN-cycled
material has been mixed with their surface layers. This is consistent
with the general consensus that RV Tau stars are in a post-AGB
evolutionary stage. There is also evidence that EP Lyr has a stellar
mass companion, but additional observations are required to calculate
an orbit; hence, EP Lyr could be a link to the group of
metal-depleted, high-latitude A-F supergiants, all of which are
binaries.
Objects:
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RA (2000) DE Designation(s)
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19 18 19.4 +27 51 03 EP Lyr
20 14 03.7 +16 43 35 R Sge = HD 192388
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3 68 211 Individual abundance results for EP Lyr
table3.tex 64 257 AASTeX version of table3
table6 76 112 Individual abundance results for R Sge
table6.tex 75 153 AASTeX version of table6
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Byte-by-byte Description of file: table3
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Bytes Format Units Label Explanations
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1- 5 A5 --- Ion Atomic species
7- 11 F5.2 --- log(Eps0) Solar abundance for the ion
13- 19 F7.2 0.1nm lambda Wavelength
21- 25 F5.2 eV EP Low energy potential
27- 32 F6.2 --- log(gf) log of oscillator strength
35- 39 F5.1 10-4nm EW1 ? Equivalent width, 1994 June 25-27
41- 44 F4.2 --- log(Eps1) ? Abundance at lambda, 1994 June 25-27
47- 51 F5.1 10-4nm EW2 ? Equivalent width, 1995 June 10&12
53- 57 F5.2 --- log(Eps2) ? Abundance at lambda, 1995 June 10&12
60- 62 I3 10-4nm EW3 ? Equivalent width, 1996 Mar 3
64- 68 F5.2 --- log(Eps3) ? Abundance at lambda, 1996 Mar 3
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Byte-by-byte Description of file: table6
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Bytes Format Units Label Explanations
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1- 5 A5 --- Ion Atomic species
7- 11 F5.2 --- log(Eps0) Solar abundance for the ion
13- 19 F7.2 0.1nm lambda Wavelength
21- 25 F5.2 eV EP Low energy potential
27- 32 F6.2 --- log(gf) log of oscillator strength
35- 37 I3 10-4nm EW1 ? Equivalent width, 1992 May 22
39- 43 F5.2 --- log(Eps1) ? Abundance at lambda, 1992 May 22
46- 48 I3 10-4nm EW2 ? Equivalent width, 1994 June 24
50- 54 F5.2 --- log(Eps2) ? Abundance at lambda, 1994 June 24
57- 59 I3 10-4nm EW3 ? Equivalent width, 1994 July 29
61- 65 F5.2 --- log(Eps3) ? Abundance at lambda, 1994 July 29
68- 70 I3 10-4nm EW4 ? Equivalent width, 1995 June 12
72- 76 F5.2 --- log(Eps4) ? Abundance at lambda, 1995 June 12
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Origin: AAS CD-ROM series, Volume 8, 1997 Lee E. Brotzman [ADS] 06-May-97
(End) [CDS] 04-Jul-1997