Variability in Proto-Planetary Nebulae: VI. Multi-Telescope Light Curves Studies of Several Medium-Bright (V=13-15), Carbon-Rich Objects
arXiv:1911.12348 · doi:10.3847/1538-3881/ab564c
Abstract
We present ten years of new photometric monitoring of the light variability of five evolved stars with strong mid-infrared emission from surrounding dust. Three are known carbon-rich proto-planetary nebulae (PPNe) with FG spectral types; the nature of the other two was previously unknown. For the three PPNe, we determine or refine the pulsation periods of IRAS 04296+3429 (71 days), 065300213 (80 days), and 23304+6147 (84 days). A secondary period was found for each, with a period ratio P/P of 0.9. The light variations are small, 0.1-0.2 mag. These are similar to values found in other PPNe. The other two are found to be giant stars. IRAS 09296+1159 pulsates with a period of only 47 days but reaches pulsational light variations of 0.5 mag. Supplemental spectroscopy reveals the spectrum of a CH carbon star. IRAS 083591644 is a G1III star that does not display pulsational variability; rather, it shows non-periodic decreases of brightness of up to 0.5 mag over this ten-year interval. These drops in brightness are reminiscent of the light curves of R Corona Borealis variables, but with much smaller decreases in brightness, and are likely due to transient dust obscuration. Its SED is very similar to that of the unusual oxygen-rich giant star HDE 233517, which possesses mid-infrared hydrocarbon emission features. These two non-PPNe turn out to members of the rare group of giant stars with large mid-infrared excesses due to dust, objects which presumably have interesting evolutionary histories.
arXiv comment25 pages, 14 figures, 1 electronic table, accepted for publication in the Astronomical Journal
References in corpus (25)
- Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2
- The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
- An HST Snapshot Survey of Proto-Planetary Nebulae Candidates: Two Types of Axisymmetric Reflection Nebulosities
- Near-Infrared Photometry of Carbon Stars
- The unusual hydrocarbon emission from the early carbon star HD 100764: The connection between aromatics and aliphatics
- A spectroscopic atlas of post-AGB stars and planetary nebulae selected from the IRAS Point Source Catalogue
- HST Snapshot Survey of Post-AGB Objects
- Innocent Bystanders: Carbon Stars from the Sloan Digital Sky Survey
- A study of the s-process in the carbon-rich post-AGB stars IRAS06530-0213 and IRAS08143-4406 on the basis of VLT-UVES spectra
- Spectroscopic Analysis of Two Carbon Rich Post-AGB Stars
- Detailed homogeneous abundance studies of 14 Galactic s-process enriched post-AGB stars: In search of lead (Pb)
- Echelle long-slit optical spectroscopy of evolved stars
- Variability in Proto-Planetary Nebulae: I. Light Curve Studies of 12 Carbon-Rich Objects
- The Remote Observatories of the Southeastern Association for Research in Astronomy (SARA)
- On Infrared Excesses Associated With Li-Rich K Giants
- Carbon stars from LAMOST DR2 data
- Polycyclic Aromatic Hydrocarbons Orbiting HD 233517, an Evolved Oxygen-Rich Red Giant
- Studies of Variability in Proto-Planetary Nebulae: II. Light and Velocity Curve Analyses of Iras 22272+5435 and 22223+4327
- Subaru/HDS study of CH stars: elemental abundances for stellar neutron-capture process studies
- Pulsations and Long-Term Light Variability of Three Candidates to Protoplanetary Nebulae
- An Abundance Analysis of the New Carbon-Rich Proto-Planetary Nebula IRAS 065300213
- Spectroscopic variability of IRAS22272+5435
- Variability in Proto-Planetary Nebulae: IV. Light Curve Analyses of Four Oxygen-Rich, F Spectral-Type Objects
- Variability in Proto-Planetary Nebulae: III. Light Curve Studies of Magellanic Cloud Carbon-Rich Objects
- Detecting Variability in Massive Astronomical Time-Series Data II: Variable Candidates in the Northern Sky Variability Survey