GK Car and GZ Nor: Two low-luminous, depleted RV Tauri stars

Abstract

We performed a photometric and spectroscopic analysis of two RV Tauri stars GK Car and GZ Nor. Both objects are surrounded by hot circumstellar dust. Their pulsation periods, derived from ASAS photometric time series, have been used to derive their luminosities and distances via the PLC relation. In addition, for both objects, GAIA distances are available. The Gaia distances and luminosities are consistent with the values obtained from the PLC relationship. GK Car is at distance of 4.5$\pm 1.3$ kpc and has a luminosity of 1520$\pm 840$ L${}_{\odot }$, while GZ Nor is at distance of 8.4$\pm 2.3$ kpc and has a luminosity of 1240 $\pm 690$ L${}_{\odot }$. Our abundance analysis reveals that both stars show depletion of refractory elements with [Fe/H]=$-$1.3 and [Zn/Ti]=$+$1.2 for GK Car and [Fe/H]=$-$2.0 and [Zn/Ti]=$+$0.8 for GZ Nor. In the WISE colour-colour diagram, GK Car is located in the RV Tauri box as originally defined by \cite{evans85} and updated by \cite{gezer15}, while GZ Nor is not. Despite this, we argue that both objects are surrounded by a gravitationally bound disc. As depletion is observed in binaries, we postulate that both stars are binaries as well. RV Tauri stars are generally acknowledged to be post$-$AGB stars. Recent studies show that they might be either indeed post$-$AGB or post$-$RGB objects depending on their luminosity. For both objects, the derived luminosities are relatively low for post-AGB objects, however, the uncertainties are quite large. We conclude that they could be either post-RGB or post-AGB objects.

arXiv commentAccepted for publication in MNRAS. 9 pages, 8 figures, 8 tables

References in corpus (38)

• The chemical composition of the Sun
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• Dust Grain Size Distributions and Extinction in the Milky Way, LMC, and SMC
• Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2
• The VizieR database of Astronomical Catalogues
• Gaia Data Release 2: using Gaia parallaxes
• Abundances of the elements in the solar system
• Estimating distances from parallaxes
• New Period-Luminosity and Period-Color Relations of Classical Cepheids: I. Cepheids in the Galaxy
• Scaled solar tracks and isochrones in a large region of the Z-Y plane. II. From 2.5 to 20 solar masses
• Keplerian discs around post-AGB stars: a common phenomenon?
• Orbital properties of binary post-AGB stars
• Extended rotating disks around post-AGB stars
• Optically visible post-AGB/RGB stars and young stellar objects in the Small Magellanic Cloud: candidate selection, spectral energy distributions and spectroscopic examination
• The MACHO Project LMC Variable Star Inventory: The Discovery of RV Tauri stars and New Type II Cepheids in the LMC
• Optically Visible Post-AGB Stars, Post-RGB Stars and Young Stellar Objects in the Large Magellanic Cloud
• Silicate features in Galactic and extragalactic post-AGB discs
• The WISE View of RV Tauri Stars
• Abundance Analyses of Field RV Tauri Stars, VI: An Extended Sample
• A newly discovered stellar type: dusty post-red giant branch stars in the Magellanic Clouds
• Abundance Analyses of Field RV Stars, V: DS Aquarii, UY Arae, TW Camelopardis, BT Librae, U Moncerotis, TT Ophiuchi, and RV Tauri
• Depletion in post-AGB stars with a dusty disc. II
• The VMC Survey. XIII. Type II Cepheids in the Large Magellanic Cloud
• Establishing binarity amongst Galactic RV Tauri stars with a disc
• CoRoT's view on variable B8/9 stars: spots versus pulsations: Evidence for differential rotation in HD 174648
• High-resolution observations of IRAS 08544-4431. Detection of a disk orbiting a post-AGB star and of a slow disk wind
• Binary central stars of planetary nebulae with long orbits: the radial velocity orbit of BD+33.2642 (PN G052.7+50.7) and the orbital motion of HD112313 (PN LoTr5)
• A mid-IR interferometric survey with MIDI/VLTI: resolving the second-generation protoplanetary disks around post-AGB binaries
• IRAS 08544-4431 : a new post-AGB star in a binary system surrounded by a dusty disc
• The evolved circumbinary disk of AC Her: a radiative transfer, interferometric and mineralogical study
• The perturbed sublimation rim of the dust disk around the post-AGB binary IRAS08544-4431
• Chemical abundance study of two strongly s-process enriched post-AGB stars in the LMC: J051213.81-693537.1 and J051848.86-700246.9
• V453 Oph: a s-process enriched, but carbon-deficient RV Tauri star of low intrinsic metallicity
• AGB nucleosynthesis in the Large Magellanic Cloud. Detailed abundance analysis of the RV Tauri star MACHO47.2496.8
• The evolutionary nature of RV Tauri stars in the SMC and LMC
• Searching for Dust around Hyper Metal-Poor Stars
• Ultra-low Amplitude Variables in the LMC -- Classical Cepheids, Pop. II Cepheids, RV Tau Stars and Binary Variables
• Binary post-AGB stars as tracers of stellar evolution

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