J/A+A/687/L17 SN 2021yja BVRI light curves (Nagao+, 2024)
Evidence for bipolar explosions in Type IIP supernovae.
Nagao T., Maeda K., Mattila S., Kuncarayakti H., Kawabata M., Taguchi K.,
Nakaoka T., Cikota A., Bulla M., Vasylyev S.S., Gutierrez C.P.,
Yamanaka M., Isogai K., Uno K., Ogawa M., Inutsuka S., Tsurumi M.,
Imazawa R., Kawabata K.S.
<Astron. Astrophys., 687, L17 (2024)>
=2024A&A...687L..17N 2024A&A...687L..17N (SIMBAD/NED BibCode)
ADC_Keywords: Supernovae ; Photometry, UBVRI
Keywords: techniques: polarimetric - supernovae: general -
supernovae: individual
Abstract:
Recent observations of core-collapse supernovae (SNe) suggest
aspherical explosions. Globally, aspherical structures in SN
explosions are thought to encode information regarding the underlying
explosion mechanism. However, the exact explosion geometries from the
inner cores to the outer envelopes are poorly understood.
Here, we present photometric, spectroscopic, and polarimetric
observations of the Type IIP SN 2021yja and discuss its explosion
geometry in comparison to those of other Type IIP SNe that show
large-scale aspherical structures in their hydrogen envelopes (SNe
2012aw, 2013ej and 2017gmr).
During the plateau phase, SNe 2012aw and 2021yja exhibit high
continuum polarization characterized by two components with
perpendicular polarization angles. This behavior can be interpreted as
being due to a bipolar explosion, where the SN ejecta is composed of a
polar (energetic) component and an equatorial (bulk) component. In
such a bipolar explosion, an aspherical axis created by the polar
ejecta would dominate at early phases, while the perpendicular axis
along the equatorial ejecta would emerge at late phases after the
photosphere in the polar ejecta has receded. Our interpretation of the
explosions in SNe 2012aw and 2021yja as bipolar is also supported by
other observational properties, including the time evolution of the
line velocities and the line shapes in the nebular spectra. The
polarization of other Type IIP SNe that show large-scale aspherical
structures in the hydrogen envelope (SNe 2013ej and 2017gmr) is also
consistent with the bipolar-explosion scenario, although this is not
conclusive.
Description:
We obtained B-, V-, R- and I-band photometry of SN 2021yja using the
Hiroshima One-shot Wide-field Polarimeter (HOWPol) mounted on the
1.5-m Kanata telescope at the Higashi-Hiroshima Observatory in Japan.
Objects:
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RA (2000) DE Designation(s)
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03 24 21.17 -21 33 56.2 SN 2021yja = AT 2021yja
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 60 40 Log of the photometric observations of SN 2021yja
and photometric measurements (Vega magnitudes)
tablec1.dat 62 17 Log of the spectroscopic observations of
SN 2021yja
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Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 8 F8.2 d MJD Modified Julian date
10- 16 F7.2 d Time Days from explosion
18- 22 F5.2 mag Bmag ?=- B magnitude (Vega)
24- 27 F4.2 mag e_Bmag ? B magnitude (Vega) error
29- 33 F5.2 mag Vmag ?=- V magnitude (Vega)
35- 38 F4.2 mag e_Vmag ? V magnitude (Vega) error
40- 44 F5.2 mag Rmag ?=- R magnitude (Vega)
46- 49 F4.2 mag e_Rmag ? R magnitude (Vega) error
51- 55 F5.2 mag Imag ?=- I magnitude (Vega)
57- 60 F4.2 mag e_Imag ? I magnitude (Vega) error
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Byte-by-byte Description of file: tablec1.dat
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Bytes Format Units Label Explanations
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1- 13 A13 "date" Date Observation date (YYYY-MM-DD.dd)
15- 22 F8.2 d MJD Modified Julian date
24- 30 F7.2 --- Phase Phase
32- 38 F7.2 d Time Days from explosion
40- 45 A6 s ExpTime Exposure time
47- 62 A16 --- Inst/Tel Instrument/Telescope
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 13-Aug-2024