arXiv subjects

D. Messier

Publications and source records attributed to D. Messier.

4 recordsLinked to original sources

arXiv2026

A multi-wavelength study of the 2025 low state of the intermediate polar BG CMi

We present multi-wavelength observations of the first recorded low state of the intermediate polar BG CMi. Optical monitoring of the source by members of the American Association of Variable Star Observers reveals a decrease of ~0.5 mag that lasted ~50 d in early 2025. During the low state the optical timing properties imply that BG CMi underwent a change in the accretion mode, as power at the spin frequency $\omega$ dramatically dropped. An XMM-Newton observation revealed a substantial decrease in intrinsic absorption and a slight increase in intrinsic X-ray luminosity, compared to archival Suzaku data. Timing analysis of the X-ray light curves shows that power shifted from the orbital frequency $\Omega$ (prominent in Suzaku data) to $2\Omega$ in the low state XMM-Newton data, along with the strengthening of certain orbital sidebands. We suggest that BG CMi transitioned to disk-overflow accretion, where the white dwarf accreted matter via both a disk and a stream, the latter becoming more dominant during the low state due to a decrease in the mass and size of the disk.

astro-ph.HE↗

arXiv2025

GOTO065054+593624: a 8.5 mag amplitude dwarf nova identified in real time via Kilonova Seekers

Dwarf novae are astrophysical laboratories for probing the nature of accretion, binary mass transfer, and binary evolution -- yet their diverse observational characteristics continue to challenge our theoretical understanding. We here present the discovery of, and subsequent observing campaign on GOTO065054+593624 (hereafter GOTO0650), a dwarf nova of the WZ Sge type, discovered in real-time by citizen scientists via the Kilonova Seekers citizen science project, which has an outburst amplitude of 8.5 mag. An extensive dataset charts the photometric and spectroscopic evolution of this object, covering the 2024 superoutburst. GOTO0650 shows an absence of visible emission lines during the high state, strong H and barely-detected HeII emission, and high-amplitude echo outbursts with a rapidly decreasing timescale. The comprehensive dataset presented here marks GOTO0650 as a candidate period bouncer, and highlights the important contribution that citizen scientists can make to the study of Galactic transients.

astro-ph.SR↗

arXiv2016

A 16-Year Photometric Campaign on the Eclipsing Novalike Variable DW Ursae Majoris

We present an analysis of photometric observations of the eclipsing novalike variable DW UMa made by the CBA consortium between 1999 and 2015. Analysis of 372 new and 260 previously published eclipse timings reveals a 13.6 year period or quasi-period in the times of minimum light. The seasonal light curves show a complex spectrum of periodic signals: both positive and negative superhumps, likely arising from a prograde apsidal precession and a retrograde nodal precession of the accretion disc. These signals appear most prominently and famously as sidebands of the orbital frequency but the precession frequencies themselves, at 0.40 and 0.22 cycles per day, are also seen directly in the power spectrum. The superhumps are sometimes seen together and sometimes separately. The depth, width and skew of eclipses are all modulated in phase with both nodal and apsidal precession of the tilted and eccentric accretion disc. The superhumps, or more correctly the precessional motions which produce them, may be essential to understanding the mysterious SW Sextantis syndrome. Disc wobble and eccentricity can both produce Doppler signatures inconsistent with the true dynamical motions in the binary, and disc wobble might boost the mass-transfer rate by enabling the hot white dwarf to directly irradiate the secondary star.

astro-ph.SR↗

arXiv2004

A New Cataclysmic Variable in Hercules

We present time-series observations, spectra and archival outburst data of a newly-discovered variable star in Hercules, Var Her 04. Its orbital period, mass ratio, and outburst amplitude resemble those of the UGWZ-type subclass of UGSU dwarf novae. However, its supercycle and outburst light curve defy classification as a clear UGWZ. Var Her 04 is most similar to the small group of possible hydrogen-burning ``period bouncers'', dwarf novae that have passed beyond the period minimum and returned.

astro-ph↗