| Name: Arkaprova Dutta |
| Affiliation: Indian Institute of Science Education and Research Kolkata |
| Conference ID: ASI2026_28 |
| Title: Century-long light curves of post-AGB stars from archival photographic plates |
| Abstract Type: Poster |
| Abstract Category: Stars, Interstellar Medium, and Astrochemistry in Milky Way |
| Author(s) and Co-Author(s) with Affiliation: Arkaprova Dutta(--), Patrick Gaulme(Thüringer Landessternwarte, Tautenburg, 07778, Germany), Ralph Neuhaeuser(Friedrich Schiller Universität Jena, Jena, 07743, Germany) |
| Abstract: We present a comprehensive analysis of century-long light curves for a selected sample of post-asymptotic giant branch (post-AGB) stars. These curves were constructed using digitised photographic plates from two independent archival data sets: the Digital Access to a Sky Century at Harvard (DASCH, DR7) and the European Archives of Photographic PLates for Astronomical USE (APPLAUSE, DR4). Our initial sample of 226 candidates was compiled from recent catalogues of Galactic post-AGB stars, leveraging a photometric baseline spanning over 100 years.
We identify long-term brightness trends in 20 sources, which may be associated with real-time stellar evolution following a late thermal flash and/or other variability phenomena with secular time-scales. Among these, 13 sources exhibit significant photometric changes. Notably, two stars show brightenings of 2.929±0.095 mag and 1.760±0.065 mag, respectively. Four other stars demonstrate variations exceeding one magnitude.
While the final crossing of the Hertzsprung gap is expected to result in moderate brightness changes and significant colour evolution, the primary objective of this ongoing work is to determine the underlying cause of the observed variability. We investigate whether these trends represent rapid evolution through the Hertzsprung-Russell Diagram (HRD) or are the result of shorter-term, secular, irregular phenomena. This study highlights the unique utility of the DASCH and APPLAUSE archives in facilitating long-term research on stellar evolution and variability. |
