An extremely fast fading population II dwarf nova candidate: caught spectroscopically on the rise

ABSTRACT In the first observational run of the Kilonova and Transients Programme (KNTraP), a rapidly evolving optical transient, KNTraP2022-02a (TNS name: AT2022kak), was discovered. This interesting burst exhibited extremely fast evolution, with a large amplitude blue outburst of $m \gt $ 3.3 in a single night, and a rapid fade back to quiescence in the following two nights. We deployed a multiwavelength follow-up campaign, monitoring the object for the next two months, but saw no recurrent burst. Three years later, while obtaining spectroscopy of the object in quiescence, there was a new outburst, enabling the collection of time-resolved spectra of the rise and fade of the outburst. The light-curve properties of the first burst and spectra of the second burst are consistent with a dwarf nova. Its rapid evolution makes it one of the fastest and faintest dwarf novae known. The estimated distance of KNTraP2022-02a from the Galactic centre is $\sim$6.6 kpc, with a scale height of $\sim$2 kpc. This scale height places it in the Galactic thick disc, where only very few dwarf novae have been found, and is therefore a potential Population II dwarf novae system.

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Publication Details

Journal
Monthly Notices of the Royal Astronomical Society
Published
2026-02-13
DOI
https://doi.org/10.1093/mnras/stag309
Primary Topic
Astrophysical Phenomena and Observations
Type
article
Field-Weighted Citation Impact
0.00

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article

An extremely fast fading population II dwarf nova candidate: caught spectroscopically on the rise

Nikita Rawat, K. Auchettl, A. W. Shafter, James Freeburn et al.
Monthly Notices of the Royal Astronomical Society
Astrophysical Phenomena and Observations
article

An extremely fast fading population II dwarf nova candidate: caught spectroscopically on the rise

Nikita Rawat, K. Auchettl, A. W. Shafter, James Freeburn, Dougal Dobie, I. Andreoni, Mark Suhr, Natasha Van Bemmel, Vanshika Kansal, Jeff Cooke, Jielai Zhang, Itumeleng Monageng, Arne Rau, D A H Buckley, Jonathan Carney, Edward N Taylor, Anais Möller, Bruce Gendre
article en

Abstract

ABSTRACT In the first observational run of the Kilonova and Transients Programme (KNTraP), a rapidly evolving optical transient, KNTraP2022-02a (TNS name: AT2022kak), was discovered. This interesting burst exhibited extremely fast evolution, with a large amplitude blue outburst of $m \gt $ 3.3 in a single night, and a rapid fade back to quiescence in the following two nights. We deployed a multiwavelength follow-up campaign, monitoring the object for the next two months, but saw no recurrent burst. Three years later, while obtaining spectroscopy of the object in quiescence, there was a new outburst, enabling the collection of time-resolved spectra of the rise and fade of the outburst. The light-curve properties of the first burst and spectra of the second burst are consistent with a dwarf nova. Its rapid evolution makes it one of the fastest and faintest dwarf novae known. The estimated distance of KNTraP2022-02a from the Galactic centre is $\sim$6.6 kpc, with a scale height of $\sim$2 kpc. This scale height places it in the Galactic thick disc, where only very few dwarf novae have been found, and is therefore a potential Population II dwarf novae system.

Monthly Notices of the Royal Astronomical SocietyVol. 547(1)
University of North Carolina at Chapel Hill (US), Goddard Space Flight Center (US), United States Department of State (US), University of Cape Town (ZA), The University of Melbourne (AU), University of the Virgin Islands (VI), The University of Western Australia (AU), University of California, Santa Cruz (US), San Diego State University (US), University of the Free State (ZA), ARC Centre of Excellence for Dark Matter Particle Physics (AU), Max Planck Institute for Extraterrestrial Physics (DE), ARC Centre of Excellence in Plant Energy Biology (AU), Joint Space Science Institute (US), South African Radio Astronomy Observatory (ZA), ARC Centre of Excellence for Gravitational Wave Discovery (AU), ARC Centre of Excellence for All-sky Astrophysics (AU), Swinburne University of Technology (AU), University of Maryland, College Park (US)
National Aeronautics and Space Administration, Space Telescope Science Institute, Queen's University Belfast, Deutsche Forschungsgemeinschaft, Queen's University, Nuclear Safety and Security Commission, Science and Technology Facilities Council, Leibniz-Gemeinschaft
Openalex Percentile: Top 55%
Astrophysical Phenomena and Observations
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