The period-luminosity and period-radius relations of Type II and anomalous Cepheids in the Large and Small Magellanic Clouds

Context. Type II Cepheids (T2Cs) and anomalous Cepheids (ACs) are pulsating stars that follow separate period-luminosity relations. Aims. We study the period-luminosity (PL) and period-radius (PR) relations for T2Cs and ACs in the Magellanic Clouds. Methods. In an accompanying paper we determined th...

Full description

Saved in:
Bibliographic Details
Published in:Astronomy and astrophysics (Berlin) 2017-08, Vol.604, p.A29
Main Authors: Groenewegen, M. A. T., Jurkovic, M. I.
Format: Article
Language:English
Subjects:
Asymptotic giant branch stars
Cepheid variables
Clouds
Dependence
Dust
Luminosity
Magellanic Clouds
Metallicity
Pulsation
Radiative transfer
Spectral energy distribution
stars: fundamental parameters
stars: variables: Cepheids
Stellar evolution
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Context. Type II Cepheids (T2Cs) and anomalous Cepheids (ACs) are pulsating stars that follow separate period-luminosity relations. Aims. We study the period-luminosity (PL) and period-radius (PR) relations for T2Cs and ACs in the Magellanic Clouds. Methods. In an accompanying paper we determined the luminosities and effective temperatures for the 335 T2Cs and ACs in the LMC and SMC discovered in the OGLE-III survey, by constructing the spectral energy distribution (SED) and fitting this with model atmospheres and a dust radiative transfer model (in the case of dust excess). Building on these results we studied the PL and PR relations of these sources. Using existing pulsation models for RR Lyrae and classical Cepheids we derive the period-luminosity-mass-temperature-metallicity relations and then estimate the pulsation mass. Results. The PL relation for the T2Cs does not appear to depend on metallicity and is Mbol = + 0.12−1.78log P (for P < 50 days), excluding the dusty RV Tau stars. Relations for fundamental and first overtone LMC ACs are also presented. The PR relation for T2C also shows little or no dependence on metallicity or period. Our preferred relation combines SMC and LMC stars and all T2C subclasses and is log R = 0.846 + 0.521log P. Relations for fundamental and first overtone LMC ACs are also presented. The pulsation masses from the RR Lyrae and classical Cepheid pulsation models agree well for the short period T2Cs, the BL Her subtype, and ACs, and are consistent with estimates in the literature, i.e. MBLH ~ 0.49M⊙ and MAC ~ 1.3M⊙, respectively. The masses of the W Vir appear similar to the BL Her. The situation for the pWVir and RV Tau stars is less clear. For many RV Tau the masses are in conflict with the standard picture of (single-star) post-AGB evolution, where the masses are either too large (≳1 M⊙) or too small (≲0.4 M⊙).
ISSN:0004-6361
1432-0746
DOI:10.1051/0004-6361/201730946