Stellar activity in a post-merger Giant star
Abstract
Binary stars are the progenitors of exotic objects, such as supernovae and gravitational wave sources. However, some systems merge earlier when the primary expands into a giant star at the end of its lifetime on the main sequence and causes its companion to spiral in. TYC 4144-329-2 is a candidate post-merger first ascent giant star with a circumstellar disk seen in the infrared (IR). We detect weak X-ray and far ultraviolet (FUV) emission from TYC 4144-329-2, which we interpret as a signature of weak coronal activity. We also find variability in Ha line profiles and in the optical light curves and we suggest an intermediate geometry where the line-of-sight passes through the upper layers of a flared disk with a time variable column density. While the X-rays must be coronal, the Ha line profiles point to ongoing and variable accretion. We suggest that TYC 4144-329-2's merger was more recent than other stars in this class and that it did not yet have time to develop a deep convection zone. If this scenario holds, TYC 4144-329-2 would be a unique probe of the earliest stages in the evolution of post-merger systems.
Related
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BibTeX
@misc{gunther2026stellar,
title = {{Stellar activity in a post-merger Giant star}},
author = {Hans Moritz Günther and C. Melis and K. J. Shen and Eric G. Blackman and K. Hoadley and P. C. Schneider},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.15652},
eprint = {2609.15652},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.15652},
note = {CC BY-SA 4.0},
}
RIS
TY - UNPB
TI - Stellar activity in a post-merger Giant star
AU - Hans Moritz Günther
AU - C. Melis
AU - K. J. Shen
AU - Eric G. Blackman
AU - K. Hoadley
AU - P. C. Schneider
PY - 2026
DA - 2026/09/17
PB - arXiv
DO - 10.48550/arxiv.2609.15652
UR - https://arxiv.org/abs/2609.15652
AB - Binary stars are the progenitors of exotic objects, such as supernovae and gravitational wave sources. However, some systems merge earlier when the primary expands into a giant star at the end of its lifetime on the main sequence and causes its companion to spiral in. TYC 4144-329-2 is a candidate post-merger first ascent giant star with a circumstellar disk seen in the infrared (IR). We detect weak X-ray and far ultraviolet (FUV) emission from TYC 4144-329-2, which we interpret as a signature of weak coronal activity. We also find variability in Ha line profiles and in the optical light curves and we suggest an intermediate geometry where the line-of-sight passes through the upper layers of a flared disk with a time variable column density. While the X-rays must be coronal, the Ha line profiles point to ongoing and variable accretion. We suggest that TYC 4144-329-2's merger was more recent than other stars in this class and that it did not yet have time to develop a deep convection zone. If this scenario holds, TYC 4144-329-2 would be a unique probe of the earliest stages in the evolution of post-merger systems.
ER -