Variability and possible rapid evolution of the hot post-AGB stars Hen 3-1347, Hen 3-1428, and LSS 4634

Abstract

We present the results of spectroscopic and photometric observations for three hot southern-hemisphere post-AGB objects, Hen 3-1347 = IRAS 17074-1845, Hen 3-1428 = IRAS17311-4924, and LSS 4634 = IRAS 18023-3409. In the spectrograms taken with the 1.9-m telescope of the South African Astronomical Observatory (SAAO) in 2012, we have measured the equivalent widths of the most prominent spectral lines. Comparison of the new data with those published previously points to a change in the spectra of Hen 3-1428 and LSS 4634 in the last 20 years. Based on ASAS data, we have detected rapid photometric variability in all three stars with an amplitude up to 0.3 mag, 0.4 mag in the $V$ band. A similarity between the patterns of variability for the sample stars and other hot protoplanetary nebulae is pointed out. We present the results of $UBV$ observations for Hen 3-1347, according to which the star undergoes rapid irregular brightness variations with maximum amplitudes $\Delta V$=0.25 mag, $\Delta B$=0.25 mag, and $\Delta U$=0.30 mag and shows color-magnitude correlations. Based on archival data, we have traced the photometric history of the stars over more than 100 years. Hen 3-1347 and LSS 4634 have exhibited a significant fading on a long time scale. The revealed brightness and spectrum variations in the stars, along with evidence for their enhanced mass, may be indicative of their rapid post-AGB evolution.

arXiv comment17 pages, 6 figures

References in corpus (13)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• Strong Emission Line HII Galaxies in the Sloan Digital Sky Survey. I. Catalog of DR1 Objects with Oxygen Abundances from Te easurements
• A spectroscopic atlas of post-AGB stars and planetary nebulae selected from the IRAS Point Source Catalogue
• Post-AGB stars with hot circumstellar dust: binarity of the low-amplitude pulsators
• An evolutionary catalogue of Galactic post-AGB and related objects
• Defining the instability strip of pulsating post-AGB binary stars from ASAS and NSVS photometry
• Variability in Proto-Planetary Nebulae: I. Light Curve Studies of 12 Carbon-Rich Objects
• Spitzer detection of PAH and silicate features in post-AGB stars and young Planetary Nebulae
• New Herbig Ae/Be stars confirmed via high-resolution optical spectroscopy
• Pulsations and Long-Term Light Variability of Three Candidates to Protoplanetary Nebulae
• Photometry and low resolution spectroscopy of hot post-AGB candidates
• IRAS\,11472-0800: an extremely depleted pulsating binary post-AGB star
• Variability of Hot Supergiant IRAS 19336-0400 in the Early Phase of its Planetary Nebula Ionization

Cited by in corpus (3)

• High-resolution spectroscopy of the high velocity hot post-AGB star IRAS 18379-1707 (LS 5112)
• Line identification and photometric history of the hot post-AGB star Hen 3-1013 (IRAS 14331-6435)
• Circumbinary disc interactions and stochastic dust obscuration in the post-asymptotic-giant-branch binary HD 213985