Abundance Analyses of Field RV Tauri Stars. V. DS Aquarii, UY Arae, TW Camelopardalis, BT Librae, U Monocerotis, TT Ophiuchi, R Scuti, and RV Tauri

Giridhar, Sunetra; Lambert, David L.; González, Guillermo

doi:10.1086/308451

Cited by 73 publications

(126 citation statements)

References 45 publications

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“…The C-type RV Tauri stars in the field and in globular clusters do not show depletion patterns and their observed initial metallicities are smaller than −1.0. It may be indicating that the depletion process is not efficient at these low initial metallicities (Giridhar et al 2000). The initial metallicity is, however, hard to determine in depleted objects.…”

Section: Disc and Chemical Depletionmentioning

confidence: 97%

“…These studies show that RV Tauri stars are mainly not enriched in C and s-process elements (e.g. Giridhar et al 1994Giridhar et al , 1998Giridhar et al , 2000Gonzalez et al 1997a,b;Van Winckel et al 1998;Maas et al 2002Maas et al , 2003Maas et al , 2005Deroo et al 2005). Earlier work suggested, for instance, the two prototypical RV Tauri stars AC Her and RU Cen to be C-enriched, based on their high [C/Fe] (Gehrz & Woolf 1970;Gehrz & Ney 1972).…”

Section: Introductionmentioning

confidence: 95%

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TheWISEview of RV Tauri stars

Gezer

Winckel

Bozkurt

et al. 2015

Mon. Not. R. Astron. Soc.

128

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We present a detailed study based on infrared photometry of all Galactic RV Tauri stars from the General Catalogue of Variable Stars (GCVS). RV Tauri stars are the brightest among the population II Cepheids. They are thought to evolve away from the asymptotic giant branch (AGB) towards the white dwarf domain. IRAS detected several RV Tauri stars because of their large IR excesses and it was found that they occupy a specific region in theWe used the all sky survey of WISE to extend these studies and compare the infrared properties of all RV Tauri stars in the GCVS with a selected sample of post-AGB objects with the goal to place the RV Tauri pulsators in the context of post-AGB evolution. Moreover, we correlated the IR properties of both the RV Tauri stars and the comparison sample with other observables like binarity and the presence of a photospheric chemical anomaly called depletion. We find that Galactic RV Tauri stars display a range of infrared properties and we differentiate between disc sources, objects with no IR excess and objects for which the spectral energy distribution (SED) is uncertain. We obtain a clear correlation between disc sources and binarity. RV Tauri stars with a variable mean magnitude are exclusively found among the disc sources. We also find evidence for disc evolution among the binaries. Furthermore our studies show that the presence of a disc seems to be a necessary but not sufficient condition for the depletion process to become efficient.

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Section: Disc and Chemical Depletionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 95%

TheWISEview of RV Tauri stars

Gezer

Winckel

Bozkurt

et al. 2015

Mon. Not. R. Astron. Soc.

128

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“…Other comparative points are the metallicity (higher in R Sct), the effective temperature (lower in R Sct) and the photometric and spectral classes which are respectively different and similar in both PAGBs. In terms of chemistry, Giridhar et al (2000) noted that the dust-gas separation in R Sct (O-rich) is limited to certain elements (with the highest condensation temperatures) and the pattern is not as strong as in the RVB AC Her for example.…”

Section: Discussionmentioning

confidence: 99%

“…with generally lower effective temperatures and less affected by the dust-gas separation following Giridhar et al 2000), there is no obvious parameter that can immediately be linked to the presence of a surface magnetic field. However we must emphasise on the small size of the sample which hampers any solid statistical analysis and also on the fact that we can not exclude any intermittent behaviour of such surface magnetic fields, as it has been reported for AGB stars (Konstantinova-Antova et al 2013).…”

Section: Discussionmentioning

confidence: 99%

“…Nordhaus et al (2007) have estimated the need for a stellar companion Barthès et al (2000), (c) Pollard & Cottrell (1995), (d) Giridhar et al (2000), (e) Stasińska et al (2006) , (f) Luck et al (1990), (g) Table 2. Observing log of the sample presenting for each object the observing date, number of Stokes V sequences, length of the sub-exposures and peak signal-to-noise ratio.…”

Section: The Samplementioning

confidence: 99%

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First detection of surface magnetic fields in post-AGB stars: the cases of U Monocerotis and R Scuti

Sabin¹,

Wade²,

Lèbre³

2014

Monthly Notices of the Royal Astronomical Society

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While several observational investigations have revealed the presence of magnetic fields in the circumstellar envelopes, jets and outflows of post-Asymptotic Giant Branch stars (PAGBs) and planetary nebulae (PNe), none has clearly demonstrated their presence at the stellar surface. The lack of information on the strength of the surface magnetic fields prevents us from performing any thorough assessment of their dynamic capability (i.e. material mixing, envelope shaping, etc). We present new high resolution spectropolarimetric (Stokes V ) observations of a sample of PAGB stars, realised with the instruments ESPaDOnS and Narval, where we searched for the presence of photospheric magnetic fields. Out of the seven targets investigated the RV Tauri stars U Mon and R Sct display a clear Zeeman signature and return a definite detection after performing a least squares deconvolution (LSD) analysis. The remaining five PAGBs show no significant detection. We derived longitudinal magnetic fields of 10.2 ± 1.7 G for U Mon and 0.6 ± 0.6 G for R Sct. In both cases the Stokes profiles point towards an interaction of the magnetic field with the atmosphere dynamics. This first discovery of weak magnetic fields (i.e. ∼10 gauss level) at the stellar surface of PAGB stars opens the door to a better understanding of magnetism in evolved stars.

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Chemical composition of post‐AGB star candidates

2018

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We present a high-resolution detailed abundance analysis for a sample of six post-Asymptotic Giant Branch (AGB) candidate stars, five of them had not been studied spectroscopically in the optical region. All the analyzed objects are Infrared Astronomical Satellite (IRAS) sources identified as possible post-AGB on the two-color IRAS diagram. We find three objects with clear signs of evolved stars; IRAS 05338 − 3051 shows abundances similar to the RV Tauri V453 Oph; the lower-luminosity stars IRAS 18025 − 3906 are O-rich without s-process enrichment and IRAS 18386 − 1253 shows a moderate selective depletion of refractory elements generally seen in post-AGB stars (PAGBs), which show midinfrared excess; they may evolve post-Red Giant Branch (RGB) objects, in which case these would be the first Galactic counterparts of post-RGB objects observed in the Large and Small Magellanic Clouds (Kamath et al. , 2015. On the other hand, IRAS 02528 + 4350 seems to be a moderately metal-poor young object and IRAS 20259 + 4206 also seems to be a young object showing carbon deficiency; however, an analysis with better spectra might be in order to clarify its evolutionary state. Finally, our abundance calculations for the binary PAGB IRAS 17279 − 1119 are found in good agreement with those of De Smedt et al. (2016).

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Abundance Analyses of Field RV Tauri Stars. V. DS Aquarii, UY Arae, TW Camelopardalis, BT Librae, U Monocerotis, TT Ophiuchi, R Scuti, and RV Tauri

Cited by 73 publications

References 45 publications

TheWISEview of RV Tauri stars

TheWISEview of RV Tauri stars

First detection of surface magnetic fields in post-AGB stars: the cases of U Monocerotis and R Scuti

Chemical composition of post‐AGB star candidates

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