AT 2019abn: multi-wavelength observations of the first 200 days. (arXiv:2001.08782v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Williams_S/0/1/0/all/0/1">S. C. Williams</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jones_D/0/1/0/all/0/1">D. Jones</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pessev_P/0/1/0/all/0/1">P. Pessev</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Geier_S/0/1/0/all/0/1">S. Geier</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Corradi_R/0/1/0/all/0/1">R. L. M. Corradi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hook_I/0/1/0/all/0/1">I. M. Hook</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Darnley_M/0/1/0/all/0/1">M. J. Darnley</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pejcha_O/0/1/0/all/0/1">O. Pejcha</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nunez_A/0/1/0/all/0/1">A. Núñez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Meingast_S/0/1/0/all/0/1">S. Meingast</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Moran_S/0/1/0/all/0/1">S. Moran</a>
AT 2019abn was discovered in the nearby M51 galaxy, by the Zwicky Transient
Facility more than two magnitudes, and around 3 weeks, prior to its optical
peak. We aimed to conduct a detailed photometric and spectroscopic follow-up
campaign for AT 2019abn, with the early discovery allowing significant
pre-maximum observations of an intermediate luminosity red transient (ILRT) for
the first time. This work is based around the analysis of u’BVr’i’z’H
photometry and low-resolution spectroscopy with the Liverpool Telescope,
medium-resolution spectroscopy with Gran Telescopio Canarias (GTC) and
near-infrared imaging with GTC and the Nordic Optical Telescope. We present the
most detailed optical light curve of an ILRT to date, with multi-band
photometry starting around three weeks before peak brightness. The transient
peaked at an observed absolute magnitude of M_r=-13.1, although it is subject
to significant reddening from dust in M51, implying an intrinsic M_r~-15.2. The
initial light curve showed a linear, achromatic rise in magnitude, before
becoming bluer at peak. After peak brightness the transient gradually cooled.
This is reflected in our spectra which at later times show absorption from
species such as Fe I, Ni I and Li I. A spectrum taken around peak brightness
shows narrow, low-velocity absorption lines, which we interpret as likely
originating from pre-existing circumstellar material. We conclude that, while
there are some peculiarities, such as the radius evolution, AT 2019abn overall
fits in well with the ILRT class of objects, and is the most luminous member of
the class seen to date.
AT 2019abn was discovered in the nearby M51 galaxy, by the Zwicky Transient
Facility more than two magnitudes, and around 3 weeks, prior to its optical
peak. We aimed to conduct a detailed photometric and spectroscopic follow-up
campaign for AT 2019abn, with the early discovery allowing significant
pre-maximum observations of an intermediate luminosity red transient (ILRT) for
the first time. This work is based around the analysis of u’BVr’i’z’H
photometry and low-resolution spectroscopy with the Liverpool Telescope,
medium-resolution spectroscopy with Gran Telescopio Canarias (GTC) and
near-infrared imaging with GTC and the Nordic Optical Telescope. We present the
most detailed optical light curve of an ILRT to date, with multi-band
photometry starting around three weeks before peak brightness. The transient
peaked at an observed absolute magnitude of M_r=-13.1, although it is subject
to significant reddening from dust in M51, implying an intrinsic M_r~-15.2. The
initial light curve showed a linear, achromatic rise in magnitude, before
becoming bluer at peak. After peak brightness the transient gradually cooled.
This is reflected in our spectra which at later times show absorption from
species such as Fe I, Ni I and Li I. A spectrum taken around peak brightness
shows narrow, low-velocity absorption lines, which we interpret as likely
originating from pre-existing circumstellar material. We conclude that, while
there are some peculiarities, such as the radius evolution, AT 2019abn overall
fits in well with the ILRT class of objects, and is the most luminous member of
the class seen to date.
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