Rights statement: The final, definitive version of this article has been published in the Journal, Astronomy and Astrophysics, 637, 2020, © EDP Sciences.
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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - AT 2019abn
T2 - multi-wavelength observations of the first 200 days
AU - Williams, S. C.
AU - Jones, D.
AU - Pessev, P.
AU - Geier, S.
AU - Corradi, R. L. M.
AU - Hook, I. M.
AU - Darnley, M. J.
AU - Pejcha, O.
AU - Núñez, A.
AU - Meingast, S.
AU - Moran, S.
N1 - The final, definitive version of this article has been published in the Journal, Astronomy and Astrophysics, 637, 2020, © EDP Sciences.
PY - 2020/5/1
Y1 - 2020/5/1
N2 - 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.
AB - 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.
KW - Astrophysics - Solar and Stellar Astrophysics
KW - Astrophysics - Astrophysics of Galaxies
U2 - 10.1051/0004-6361/201937286
DO - 10.1051/0004-6361/201937286
M3 - Journal article
VL - 637
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
SN - 0004-6361
M1 - A20
ER -