_version_ 1866911265927987200
author Esseldeurs, Mats
Decin, Leen
De Ridder, Joris
Mori, Yoshiya
Karakas, Amanda I.
Malfait, Jolien
Danilovich, Taïssa
Mathis, Stéphane
Richards, Anita M. S.
Saha, Raghvendra
Yates, Jeremy
Van de Sande, Marie
Baes, Maarten
Baudry, Alain
Bolte, Jan
Ceulemans, Thomas
De Ceuster, Frederik
Mellah, Ileyk El
Etoka, Sandra
Gottlieb, Carl
Herpin, Fabrice
Kervella, Pierre
Landri, Camille
Marinho, Louise
McDonald, Iain
Menten, Karl
Millar, Tom
Osborn, Zara
Pimpanuwat, Bannawit
Plane, John
Price, Daniel J.
Siess, Lionel
Vermeulen, Owen
Wong, Ka Tat
author_facet Esseldeurs, Mats
Decin, Leen
De Ridder, Joris
Mori, Yoshiya
Karakas, Amanda I.
Malfait, Jolien
Danilovich, Taïssa
Mathis, Stéphane
Richards, Anita M. S.
Saha, Raghvendra
Yates, Jeremy
Van de Sande, Marie
Baes, Maarten
Baudry, Alain
Bolte, Jan
Ceulemans, Thomas
De Ceuster, Frederik
Mellah, Ileyk El
Etoka, Sandra
Gottlieb, Carl
Herpin, Fabrice
Kervella, Pierre
Landri, Camille
Marinho, Louise
McDonald, Iain
Menten, Karl
Millar, Tom
Osborn, Zara
Pimpanuwat, Bannawit
Plane, John
Price, Daniel J.
Siess, Lionel
Vermeulen, Owen
Wong, Ka Tat
contents Close companions influence stellar evolution through tidal interactions, mass transfer, and mass loss effects. While such companions are detected around young stellar objects, main-sequence stars, red giants, and compact objects, direct observational evidence of close-in companions around asymptotic giant branch (AGB) stars has remained elusive. Here, we present (sub)millimeter time-domain imaging spectroscopy revealing the Keplerian motion of a close-in companion around the AGB star pi1 Gruis. The companion, slightly more massive than the AGB star, is likely a main-sequence star. Unlike more evolved stars with companions at comparable distances, pi1 Gru's companion follows a circular orbit, suggesting an eccentricity-generating mechanism late- or post-AGB. Our analysis suggests that model-predicted circularization rates may be underestimated. Our results highlight the potential of multi-epoch (sub)millimeter interferometry in detecting the Keplerian motion of close companions to giant stars and open avenues for our understanding of tidal interaction physics and binary evolution.
format Preprint
id arxiv_https___arxiv_org_abs_2511_11247
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Evidence for the Keplerian orbit of a close companion around a giant star
Esseldeurs, Mats
Decin, Leen
De Ridder, Joris
Mori, Yoshiya
Karakas, Amanda I.
Malfait, Jolien
Danilovich, Taïssa
Mathis, Stéphane
Richards, Anita M. S.
Saha, Raghvendra
Yates, Jeremy
Van de Sande, Marie
Baes, Maarten
Baudry, Alain
Bolte, Jan
Ceulemans, Thomas
De Ceuster, Frederik
Mellah, Ileyk El
Etoka, Sandra
Gottlieb, Carl
Herpin, Fabrice
Kervella, Pierre
Landri, Camille
Marinho, Louise
McDonald, Iain
Menten, Karl
Millar, Tom
Osborn, Zara
Pimpanuwat, Bannawit
Plane, John
Price, Daniel J.
Siess, Lionel
Vermeulen, Owen
Wong, Ka Tat
Solar and Stellar Astrophysics
Close companions influence stellar evolution through tidal interactions, mass transfer, and mass loss effects. While such companions are detected around young stellar objects, main-sequence stars, red giants, and compact objects, direct observational evidence of close-in companions around asymptotic giant branch (AGB) stars has remained elusive. Here, we present (sub)millimeter time-domain imaging spectroscopy revealing the Keplerian motion of a close-in companion around the AGB star pi1 Gruis. The companion, slightly more massive than the AGB star, is likely a main-sequence star. Unlike more evolved stars with companions at comparable distances, pi1 Gru's companion follows a circular orbit, suggesting an eccentricity-generating mechanism late- or post-AGB. Our analysis suggests that model-predicted circularization rates may be underestimated. Our results highlight the potential of multi-epoch (sub)millimeter interferometry in detecting the Keplerian motion of close companions to giant stars and open avenues for our understanding of tidal interaction physics and binary evolution.
title Evidence for the Keplerian orbit of a close companion around a giant star
topic Solar and Stellar Astrophysics
url https://arxiv.org/abs/2511.11247