J/A+A/700/A138 SN 2022lxg light curves (Charalampopoulos+, 2025)
Luminous, rapidly declining supernovae as stripped transitional objects in low
metallicity environments: The case of SN 2022lxg.
Charalampopoulos P., Kotak R., Sollerman J., Gutierrez C.P., Pursiainen M.,
Killestein T.L., Schulze S., Pessi P.J., Maeda K., Kangas T., Cai Y.-Z.,
Fremling C., Hinds K.R., Jegou du Laz T., Kankare E., Kasliwal M.,
Kuncarayakti H., Lundqvist P., Masci F.J., Mattila S., Perley D.A.,
Reguitti A., Reynolds T.M., Stritzinger M., Tartaglia L., Van Roestel J.,
Wold A.
<Astron. Astrophys. 700, A138 (2025)>
=2025A&A...700A.138C 2025A&A...700A.138C (SIMBAD/NED BibCode)
ADC_Keywords: Supernovae ; Photometry, SDSS ; Optical
Keywords: circumstellar matter - stars: mass loss - supernovae: general -
supernovae: individual: SN 2022lxg
Abstract:
We present an analysis of the optical and near-infrared properties of
SN 2022lxg, a bright (Mgpeak=-19.41mag) and rapidly evolving SN. It
was discovered within a day of explosion, and rose to peak brightness
in ∼10d. Two distinct phases of circumstellar interaction are evident
in the data. The first is marked by a steep blue continuum (T>15000K)
with flash-ionisation features due to hydrogen and HeII. The second,
weaker phase is marked by a change in the colour evolution accompanied
by changes in the shapes and velocities of the spectral line profiles.
Narrow P-Cygni profiles (∼150km/s) of HeI further indicate the
presence of slow-moving unshocked material and suggesting partial
stripping of the progenitor. The fast decline of the light curve from
peak (3.48±0.26mag(50d)-1 in g-band) implies that the ejecta mass
must be low. Spectroscopically, until +35d there are similarities to
some Type IIb SNe but then there is a transition to spectra that are
more reminiscent of an interacting SN II. However, metal lines are
largely absent in the spectra, even at epochs of ∼80d. Its remote
location (∼4.6kpc projected offset) from the presumed host galaxy, a
dwarf with MB~-14.4mag, is consistent with our metallicity estimate --
close to the Small Magellanic Cloud value -- obtained from scaling
relations. Furthermore, several lines of evidence (including intrinsic
polarisation of p~(0.5-1.0)%) point to deviations from spherical
symmetry. We suggest that a plausible way of uniting the observational
clues is to consider a binary system that underwent case C mass
transfer. This failed to remove the entire H-envelope of the
progenitor before it underwent core-collapse. In this scenario, the
progenitor itself would be more compact and perhaps straddle the
boundary between blue and yellow supergiants, tying in with the early
spectroscopic similarity to Type IIb SNe.
Description:
We acquired well-sampled imaging and spectroscopy, and three epochs of
imaging polarimetry from a range of telescopes.
We obtained gri imaging with a roughly 2-3d cadence via the
Zwicky Transient Facility (ZTF), the Palomar Schmidt 48-inch (P48)
Samuel Oschin and the Spectral Energy Distribution Machine Rainbow
Camera on the Palomar 60-inch telescope (SEDM)
We were able to collect 28 spectra of SN 2022lxg spanning ∼2∼90d. The
earliest spectrum was obtained using the Low-Resolution Imaging
Spectrometer (LRIS) on the Keck I 10-m telescope.
We were also able to obtain three epochs of imaging polarimetry (18
June 2022, 7 July 2022, 18 July 2022) with ALFOSC at the NOT in the V
and R filters.
Photometry of SN 2022lxg. It contains the six followinbg columns:
Date, MJD, Phase wrt explosion epoch (d), Telescope, Band, Magnitude
(mag). All reported magnitudes are in the AB system and are host
subtracted but not dereddened for Milky Way reddening. The table is
sorted from bluest to reddest band. A value of 99 in the error refers
to an upper-limit.
Objects:
--------------------------------------------
RA (2000) DE Designation(s)
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19 15 23.630 +48 19 27.70 SN 2022lxg
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 47 218 Photometry of SN 2022lxg
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 "date" Date Observation date
12- 19 F8.2 d MJD Modified Julain date
21- 26 F6.2 d Phase Phase wrt to explosion epoch
28- 32 A5 --- Tel Telescope
34 A1 --- Band [oc griz] Band
36 A1 --- l_mag Upper limit flag on mag
37- 41 F5.2 mag mag Magnitude in Band
43- 47 F5.2 mag e_mag ?=99 Magnitude in Band error
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Acknowledgements:
Pacha Charalampopoulos, pachar(at)utu.fi
(End) Patricia Vannier [CDS] 19-Jun-2025