The terminal moraine of the Seal-Churchill Divide

Alcock, F J

doi:10.4095/103625

Cited by 29 publications

(57 citation statements)

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“…In oxygen-rich gas, the heavy elements are among the first to be removed from the gas as cooling occurs. The demonstration by Alcock et al (1998) that the RV Tau and type II Cepheids in the LMC define a single period-luminosity-color relation suggests that the longer period type II Cepheids in our sample may be susceptible to dust-gas separation. Earlier, we noted that several of our stars show RV TauYlike photometric behavior and might be promoted from W Vir to RV Tau status.…”

Section: Accounting For the Anomaliesmentioning

confidence: 99%

“…There is ample evidence that the W Vir and RV Tau stars have much in common. For example, photometry of type II Cepheids and RV Tau stars in the Large Magellanic Cloud (LMC) shows clearly that the RV Tau stars and the type II Cepheids define a common period-luminosity-color relation (Alcock et al 1998). Given this commonality, the question naturally arises: what abundance anomalies are shown by the BL Her and W Vir stars and are those anomalies similar to those shown by the RV Tau stars?…”

Section: Introductionmentioning

confidence: 99%

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The Chemical Compositions of the Type II Cepheids—The BL Herculis and W Virginis Variables

Maas

Giridhar

Lambert

2007

ApJ

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Abundance analyses from high-resolution optical spectra are presented for 19 type II Cepheids in the Galactic field. The sample includes both short-period ( BL Her) and long-period (W Vir) stars. This is the first extensive abundance analysis of these variables. The C, N, and O abundances with similar spreads for the BL Her and W Vir show evidence for an atmosphere contaminated with 3 process and CN-cycling products. A notable anomaly of the BL Her stars is an overabundance of Na by a factor of about 5 relative to their presumed initial abundances. This overabundance is not seen in the W Vir stars. The abundance anomalies running from mild to extreme in W Vir stars but not seen in the BL Her stars are attributed to dust-gas separation that provides an atmosphere deficient in elements of high condensation temperature, notably, Al, Ca, Sc, Ti, and s-process elements. Such anomalies have previously been seen among RV Tau stars which represent a long-period extension of the variability enjoyed by the type II Cepheids. Comments are offered on how the contrasting abundance anomalies of BL Her and W Vir stars may be explained in terms of the stars' evolution from the blue horizontal branch.

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Section: Accounting For the Anomaliesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Chemical Compositions of the Type II Cepheids—The BL Herculis and W Virginis Variables

Maas

Giridhar

Lambert

2007

ApJ

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“…The luminosity of MACHO*04:55:43.2-67:51:10 (Mv = -3.87, Alcock et al 1998) is higher than those typical of the RV Tauri stars present in galactic globular clusters, but there is a rich intermediate-age population in the LMC, typified by the globular clusters, from which such a star might come. Carbon enrichment on the extended AGB of these clusters ultimately results in N-type carbon stars (Bessell, Wood & Lloyd Evans 1983), so the enhancement of carbon I(.R.…”

Section: Infrared Photometrymentioning

confidence: 98%

“…The discovery of RV Tauri stars in the Large Magellanic Cloud (LMC) was announced recently Alcock et al 1998). This discovery has finally allowed us to make a definitive assessment of the luminosities of these stars which will help us in our investigation of the other fundamental parameters.…”

Section: Rv Tauri Stars In the Large Magellanic Cloudmentioning

confidence: 99%

“…This paper presents the first spectroscopic results obtained for an RV Tauri star in the LMC. MACHO*04:55:43.2-67:51:10 has a formal period of 112.45 days and is the longest period variable from the Alcock et al (1998) sample of 33 Type II Cepheid and RV Tauri stars in the LMC. The light curve is shown in Fig.…”

Section: Rv Tauri Stars In the Large Magellanic Cloudmentioning

confidence: 99%

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RV Tauri stars and Type II Cepheids in the LMC

Pollard

Evans

1999

Symp. - Int. Astron. Union

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Abstract. A review of the main results from the MACHO project for RV Tauri stars and Type II Cepheids in the LMC is presented. In light and colour curve behaviour, the RV Tauri stars appear to be a direct extension of the Type II Cepheids to longer periods. A single periodluminosity-colour relationship is seen to describe both the Type II Cepheids and RV Tauri stars in the LMC.Follow-up low resolution spectroscopy of the LMC RV Tauri stars has been undertaken. The spectra of the longest period RV Tauri star in the MACHO sample show that this star has strong C 2 bands with a pronounced phase dependence, their strength being greater at minimum light. This and other spectral features are similar to those observed in proto-planetary nebulae. This LMC star therefore appears to combine the main spectral anomaly of the proto-planetary nebulae with RV Tauri-like photometric variability. This is an intriguing result which indicates a possible link between RV Tauri stars and proto-planetary nebulae, and strengthens the post-AGB interpretation of the RV Tauri stars.

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The Nature of RV Tauri Stars

Evans

1999

Symp. - Int. Astron. Union

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The infrared colours of the RV Tauri stars fall in a well-defined and thinly-populated region of the IRAS [12] – [25], [25] – [60] diagram. This provides an alternative method of searching for such stars. Stars with these IRAS colours as well as the K and L excesses which are also typical of RV Tauri stars have spectral types from B to M. The characteristic variability of RV Tauri-type has been found for several stars with spectral types typical of known RV Tauri stars, while stars of different spectral types do not vary in this way. RV Tauri stars are the stars with these colours, probably indicative of a dusty circumstellar disk, which lie within the Cepheid instability strip.

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The terminal moraine of the Seal-Churchill Divide

Cited by 29 publications

References 0 publications

The Chemical Compositions of the Type II Cepheids—The BL Herculis and W Virginis Variables

The Chemical Compositions of the Type II Cepheids—The BL Herculis and W Virginis Variables

RV Tauri stars and Type II Cepheids in the LMC

The Nature of RV Tauri Stars

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