Brightness and mass accretion rate evolution during the 2022 burst of EX~Lupi
Journal
Date Issued
2023
Author(s)
Cruz-Sáenz de Miera, F.
•
Kóspál, Á.
•
Ábrahám, P.
•
Claes, R. A. B.
•
Manara, C. F.
•
Wendeborn, J.
•
Fiorellino, E.
•
•
•
Sicilia-Aguilar, A.
•
Campbell-White, J.
•
•
Banzatti, A.
•
Szabó, Zs. M.
•
Lykou, F.
•
•
Varga, J.
•
Siwak, M.
•
Park, S.
•
Nagy, Zs.
•
Kun, M.
Abstract
EX Lupi is the prototype by which EXor-type outbursts were defined. It has
experienced multiple accretion-related bursts and outbursts throughout the last
decades, whose study have greatly extended our knowledge about the effects of
these types of events. This star experienced a new burst in 2022. We used
multi-band photometry to create color-color and color-magnitude diagrams to
exclude the possibility that the brightening could be explained by a decrease
in extinction. We obtained VLT/X-shooter spectra to determine the Lacc and Macc
during the peak of the burst and after its return to quiescence using 2
methods: empirical relationships between line luminosity and Lacc, and a slab
model of the whole spectrum. We examined the 130 year light curve of EX Lupi to
provide statistics on the number of outbursts experienced during this period of
time. Our analysis of the data taken during the 2022 burst confirmed that a
change in extinction is not responsible for the brightening. Our two approaches
in calculating the Macc were in agreement, and resulted in values that are 2
orders of magnitude above what had previously been estimated, thus suggesting
that EX Lupi is a strong accretor even when in quiescence. We determined that
in 2022 March the Macc increased by a factor of 7 with respect to the quiescent
level. We also found hints that even though the Macc had returned to almost its
pre-outburst levels, certain physical properties of the gas had not returned to
the quiescent values. We found that the mass accreted during this three month
event was 0.8 lunar masses, which is approximately half of what is accreted
during a year of quiescence. We calculated that if EX Lupi remains as active as
it has been for the past 130 years, during which it has experienced at least 3
outbursts and 10 bursts, then it will deplete the mass of its circumstellar
material in less than 160000 yr.
Volume
678
Start page
A88
Issn Identifier
0004-6361
Rights
open.access
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