2 research outputs found
SN 2022joj: A Peculiar Type Ia Supernova Possibly Driven by an Asymmetric Helium-shell Double Detonation
We present observations of SN 2022joj, a peculiar Type Ia supernova (SN Ia)
discovered by the Zwicky Transient Facility (ZTF). SN 2022joj exhibits an
unusually red color at early times and a rapid
blueward evolution afterwards. Around maximum brightness, SN 2022joj shows a
high luminosity ( mag), a blue
broadband color ( mag), and shallow Si
II absorption lines, consistent with those of overluminous, SN 1991T-like
events. The maximum-light spectrum also shows prominent absorption around 4200
\r{A}, which resembles the Ti II features in subluminous, SN 1991bg-like
events. Despite the blue optical-band colors, SN 2022joj exhibits extremely red
ultraviolet optical colors at maximum luminosity ( mag and
mag), suggesting a suppression of flux between
2500--4000 \r{A}. Strong C II lines are also detected at peak. We show
that these unusual spectroscopic properties are broadly consistent with the
helium-shell double detonation of a sub-Chandrasekhar mass
() carbon/oxygen (C/O) white dwarf (WD) from a
relatively massive helium shell (--), if
observed along a line of sight roughly opposite to where the shell initially
detonates. None of the existing models could quantitatively explain all the
peculiarities observed in SN 2022joj. The low flux ratio of [Ni II]
7378 to [Fe II] 7155 emission in the late-time nebular
spectra indicates a low yield of stable Ni isotopes, favoring a
sub-Chandrasekhar mass progenitor. The significant blueshift measured in the
[Fe II] 7155 line is also consistent with an asymmetric chemical
distribution in the ejecta, as is predicted in double-detonation models.Comment: 24 pages, 11 figures, 6 tables. Submitted to Ap
SN 2022joj: A Peculiar Type Ia Supernova Possibly Driven by an Asymmetric Helium-shell Double Detonation
International audienceWe present observations of SN 2022joj, a peculiar Type Ia supernova (SN Ia) discovered by the Zwicky Transient Facility (ZTF). SN 2022joj exhibits an unusually red color at early times and a rapid blueward evolution afterwards. Around maximum brightness, SN 2022joj shows a high luminosity ( mag), a blue broadband color ( mag), and shallow Si II absorption lines, consistent with those of overluminous, SN 1991T-like events. The maximum-light spectrum also shows prominent absorption around 4200 Å, which resembles the Ti II features in subluminous, SN 1991bg-like events. Despite the blue optical-band colors, SN 2022joj exhibits extremely red ultraviolet optical colors at maximum luminosity ( mag and mag), suggesting a suppression of flux between 2500--4000 Å. Strong C II lines are also detected at peak. We show that these unusual spectroscopic properties are broadly consistent with the helium-shell double detonation of a sub-Chandrasekhar mass () carbon/oxygen (C/O) white dwarf (WD) from a relatively massive helium shell (--), if observed along a line of sight roughly opposite to where the shell initially detonates. None of the existing models could quantitatively explain all the peculiarities observed in SN 2022joj. The low flux ratio of [Ni II] 7378 to [Fe II] 7155 emission in the late-time nebular spectra indicates a low yield of stable Ni isotopes, favoring a sub-Chandrasekhar mass progenitor. The significant blueshift measured in the [Fe II] 7155 line is also consistent with an asymmetric chemical distribution in the ejecta, as is predicted in double-detonation models