J/A+A/707/A157 SN 2024acyl light curves (Cai+, 2026)
Massive stars exploding in a He-rich circumstellar medium.
XII. SN 2024acyl: A fast, linearly declining Type Ibn supernova with early
flash-ionisation features.
Cai Y.-Z., Pastorello A., Maeda K., Zhao J.-W., Wang Z.-Y., Peng Z.-H.,
Reguitti A., Tartaglia L., Filippenko A.V., Pan Y., Valerin G., Kumar B.,
Wang Z., Fraser M., Anderson J.P., Benetti S., Bose S., Brink T.G.,
Cappellaro E., Chen T.-W., Chen X.-L., Elias-Rosa N., Esamdin A.,
Gal-Yam A., Gonzalez-Banuelos M., Gromadzki M., Gutierrez C.P.,
Inserra C., Iskandar A., Kangas T., Kankare E., Kravtsov T.,
Kuncarayakti H., Li L.-P., Liu C.-X., Liu X.-K., Lundqvist P.,
Matilainen K., Mattila S., Moran S., Mueller-Bravo T.E., Nagao T.,
Petrushevska T., Pignata G., Salmaso I., Smartt S.J., Sollerman J.,
Srivastav S., Stritzinger M.D., Wang L.-T., Yan S.-Y., Yang Y.,
Yang Y.-P., Zheng W., Zou X.-Z., Chen L.-Y., Du X.-L., Fang Q.-L.,
Fiore A., Ragosta F., Zha S., Zhang J.-J., Liu X.-W., Bai J.-M., Wang B.,
Wang X.-F.
<Astron. Astrophys. 707, A157 (2026)>
=2026A&A...707A.157C 2026A&A...707A.157C (SIMBAD/NED BibCode)
ADC_Keywords: Supernovae ; Photometry ; Optical ; Ultraviolet
Keywords: circumstellar matter - supernovae: general -
supernovae: individual: SN 2024acyl
Abstract:
We present a photometric and spectroscopic analysis of the Type Ibn
supernova (SN) 2024acyl. It rises to an absolute magnitude peak of
M_o=-17.58±0.15mag in 10.6 days, and displays a rapid linear
post-peak light-curve decline in all bands (e.g.,
gamma0-60(V)=0.097±0.002mag/d), similar to most SNe Ibn. The
optical pseudobolometric light curve peaks at (3.5±0.8)x1042erg/s,
with a total radiated energy of (5.0±0.4)x1048erg. The spectra are
dominated by a blue continuum at early stages, with narrow P-Cygni HeI
lines and flash-ionisation emission lines of CIII, NIII, and HeII. The
P-Cygni HeI features gradually evolve and become emission-dominated
in late-time spectra. The H-alpha line is detected throughout the
entire spectral evolution, which indicates that the circumstellar
material (CSM) is helium-rich with some residual amount of hydrogen.
Our multiband light-curve modelling yields estimates of the ejecta
mass of Mej=0.49+0.11-0.09M☉, with a kinetic energy of
Ek=0.06+0.01-0.01x1051erg, and a 56Ni mass of
MNi=0.018M☉. The inferred CSM properties are characterised by
a mass of MCSM= 0.51 (+0.05/-0.04) M_sun, an inner radius of
R0=17.8+3.6-3.0AU, and a density
rhoCSM=(8.3+2.7-1.2)x10-12g/cm3. The multi-epoch spectra are
well reproduced by the CMFGEN/he4p0 model, corresponding to a He-ZAMS
mass of 4M☉ (H-ZAMS mass 18.11M☉, pre-SN mass
3.16M☉). These findings are consistent with a scenario of an SN
powered by ejecta-CSM interaction, originating from a low-mass helium
star that evolved within an interacting binary system where the CSM
with some residual hydrogen may originate from the mass-transfer
process. We also discuss an extreme scenario involving the possible
merger of a helium white dwarf. In addition, a channel of
core-collapse (CC) explosion of a late-type Wolf-Rayet (WR) star with
hydrogen (WNH), or a transitional star between an Of and a WR type
(e.g., an Ofpe/WN9 star) with fallback accretion, cannot be entirely
ruled out.
Description:
The multi-band photometric data for SN 2024acyl.
Objects:
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RA (2000) DE Designation(s)
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02 46 05.326 +28 01 17.91 SN 2024acyl
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 82 325 The multi-band photometric data for SN 2024acyl
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 23 A23 "datime" Date Observation date
25- 32 F8.2 d MJD Modified Julian Date
34- 39 F6.2 d Phase Phase in days relative to maximum light
41- 46 F6.3 mag mag Observed apparent magnitude in Band
48- 52 F5.3 mag e_mag Uncertainty of the magnitude in Band
54- 57 A4 --- Band Photometric filter/band name (1)
59- 62 A4 --- System Photometric system (e.g. Vega, AB)
64 A1 --- Type [PU] P = detection, U = upper limit
66- 73 A8 --- Inst Name of the instrument
75- 82 A8 --- Tel Name of the telescope
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Note (1): Bands are U, B, V, u, g, r, i, z, um, vm, UVM2, UVW1, UVW2, c and o.
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Acknowledgements:
Yongzhi Cai, caiyongzhi789(at)gmail.com
(End) Patricia Vannier [CDS] 27-Jan-2026