Gaia23bab: A New EXor

Author(s): T. Giannini, E. Schisano, B. Nisini, P. Ábrahám, S. Antoniucci, K. Biazzo, F. Cruz-Sáenz de Miera, E. Fiorellino, M. Gangi, A. Kóspál, M. Kuhn, E. Marini, Z. Nagy, D. Paris
Abstract: On 2023 March 6, the Gaia telescope alerted a 2 mag burst from Gaia23bab, a young stellar object in the Galactic plane. We observed Gaia23bab with the Large Binocular Telescope obtaining optical and near-infrared spectra close in time to the peak of the burst, and collected all public multiband photometry to reconstruct the historical light curve. The latter shows three bursts in 10 years (2013, 2017, and 2023), whose duration and amplitude are typical of EXor variables. We estimate that, due to the bursts, the mass accumulated on the star is about twice greater than if the source had remained quiescent for the same period of time. Photometric analysis indicates that Gaia23bab is a class II source with age ≲1 Myr, spectral type G3−K0, stellar luminosity ∼4.0 L _⊙, and mass ∼1.6 M _⊙. The optical/near-infrared spectrum is rich in emission lines. From the analysis of these lines we measured an accretion luminosity and mass accretion rate (L _acc^burst ∼ 3.7 L _⊙, M ̇ acc ^burst ∼ 2.0 × 10⁻⁷ M _⊙ yr⁻¹) consistent with those of EXors. More generally, we derived the relationships between accretion and stellar parameters in a sample of EXors. We find that, when in burst, the accretion parameters become almost independent of the stellar parameters and that EXors, even in quiescence, are more efficient than classical T Tauri stars in assembling mass.
Organisation(s): Department of Astrophysics
External organisation(s): INAF - Osservatorio Astronomico di Roma, INAF-Osservatorio Astrofisico di Torino, Eötvös Loránd Research Network, Hungarian Academy of Sciences, Eötvös Loránd University Budapest, University of Toulouse, INAF Astronomical Observatory of Capodimonte , Space Science Data Center (SSDC) - Agenzia Spaziale Italiana (ASI), Max-Planck-Institut für Astronomie, University of Hertfordshire
Journal: Astrophysical Journal
Volume: 967
No. of pages: 12
ISSN: 0004-637X
DOI: https://doi.org/10.3847/1538-4357/ad39e2
Publication date: 05-2024
Peer reviewed: Yes
Austrian Fields of Science 2012: 103003 Astronomy, 103004 Astrophysics
ASJC Scopus subject areas: Astronomy and Astrophysics, Space and Planetary Science
Portal url: https://ucrisportal.univie.ac.at/en/publications/da645966-c9c1-4521-a016-c1e522862ba9

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