Unveiling the white dwarf in the eclipsing polar HU Aquarii
A.D. Schwope, T.R. Marsh, S.G. Parsons, J. Vogel, V.S. Dhillon

TL;DR
This study precisely measures the white dwarf's mass and accretion regions in HU Aquarii during a low state, revealing detailed accretion geometry and magnetic field interactions with unprecedented accuracy.
Contribution
First direct and highly accurate measurement of the white dwarf's size and mass in HU Aquarii using low-state photometry and light curve modeling.
Findings
White dwarf mass is 0.78 ± 0.02 Msun.
Accretion regions show a 30° longitudinal shift.
Detected a warm region at ~33,000 K in the low state.
Abstract
We present an analysis of high-speed u- and r-band photometry of the eclipsing polar HU Aquarii that was obtained with ULTRACAM mounted on the VLT. The observations were performed during a low state, permitting us for the first time to determine the contact points of the white dwarf. Using LCURVE we could determine its size, and hence mass, with a direct method and with unprecedented accuracy. We determined the mass of the white dwarf as 0.78 +- 0.02 Msun, the mass ratio Q= MWD / Msec = 4.59, and the orbital inclination i=87.4 +- 0.9. An extended warm region with a central temperature of ~33,000 K was observed in the u-band at the location of the previous high-state accretion spot. Weak accretion was ongoing in the low state that led to cyclotron emission that could best be studied with the r-band data. It has a diameter of only 3deg to 4deg and is located much closer to the binary…
Peer Reviews
No public reviews on file for this paper yet. If you reviewed it on a platform where reviews are public (OpenReview, ICLR, NeurIPS, ICML), you can paste yours below so the community can read it here.
Videos
No videos yet. Explain this paper in a talk, walkthrough, or lecture? Add one.
Taxonomy
TopicsAstrophysical Phenomena and Observations · Astrophysics and Star Formation Studies · Astronomy and Astrophysical Research
