| Name: | Judhajeet Basu |
| Affiliation: | Indian Institute of Astrophysics, Bangalore |
| Conference ID : | ASI2024_360 |
| Title : | M31 nova survey using GIT and UVIT with a focus on the multiple eruptions of the remarkable recurrent nova M31N 2008-12a |
| Authors : | Judhajeet Basu [12], M. Pavana [12], G.C. Anupama [1], Sudhanshu Barway [1], K.P. Singh [3], Vishwajeet Swain [4], Shubham Srivastav [5], Harsh Kumar [467], Varun Bhalerao [4], L.S. Sonith [12], Shatakshi Chamoli [1], Dhananjay Raman [8], Ravi Kumar [9] |
| Authors Affiliation: | 1. Indian Institute of Astrophysics, Bangalore - 560034, India
2. Pondicherry University, Puducherry - 605014, India
3. Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Mohali - 140306, India
4. Physics Department, Indian Institute of Technology Bombay, Mumbai - 400076, India
5. Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast - BT7 1NN, UK
6. Harvard College Observatory, Harvard University, Cambridge - 02158 MA, USA
7. Center for Astrophysics, Harvard University, Cambridge - 02158 MA, USA
8. Department of Computer Science and Engineering, IIT Bombay, Powai, Mumbai - 400076, India
9. Department of Aerospace Engineering, IIT Bombay, Powai, Mumbai - 400076, India |
| Mode of Presentation: | Poster |
| Abstract Category : | High Energy Phenomena, Fundamental Physics and Astronomy |
| Abstract : | M31, being the nearest large galaxy, is a treasure for nova hunters. The high nova rate of 40/year (Rector et al. 2022) has motivated us to survey M31 in optical (GIT/HCT) and UV (UVIT). GIT's large FoV makes it possible to observe M31 in 7 pointings with an exposure of 300s each in g’ and r’ filters at daily cadence. Since the beginning of the survey in 2022, more than 15 novae have been detected and followed up photometrically, and spectra have been obtained for 7 novae using the HCT. We also have an accepted UVIT monitoring proposal at a cadence of 14 days for cycle A13. Preliminary results from the ongoing survey, which include light curves, optical spectra and UV detections, will be presented.
One extremely interesting nova in M31 is 2008-12a, which shows a recurrence period of about 1 year. Optical, UV, and X-ray observations of the 2017-2022 eruptions of this recurrent nova, based on Basu et al. (2023, under review), are presented here. In this work, we inferred a steady decrease in the accretion rate over the years based on the inter-eruption recurrence period. A “cusp” feature in the r’ and i’ band light curves close to the peak was detected, which could be associated with jets. Ejecta mass and He abundance were obtained from spectral modelling. We also detected variability during the SSS phase, which is anti-correlated with the UV emission, indicating a common origin, probably due to the accretion disk reformation. A comparison of the accretion rate with different models on the ‘WD mass - accretion rate’ plane yielded the CO WD erupting every 1 year to be near the Chandrasekhar limit and growing with time, making M31N 2008-12a a strong candidate for the single degenerate scenario of Type Ia supernovae progenitor. |
