E. Dennihy

Outbursts in two new cool pulsating DA white dwarfs

The unprecedented extent of coverage provided by Kepler observations recently revealed outbursts in two hydrogen-atmosphere pulsating white dwarfs (DAVs) that cause hours-long increases in the overall mean flux of up to 14%. We have identified two new outbursting pulsating white dwarfs in K2, bringing the total number of known outbursting white dwarfs to four. EPIC 211629697, with

Two white dwarfs in ultrashort binaries with detached, eclipsing, likely substellar companions detected by K2

{T}_{\mathrm{eff}}

A SUBTLE INFRARED EXCESS ASSOCIATED WITH A YOUNG WHITE DWARF IN THE EDINBURGH-CAPE BLUE OBJECT SURVEY

= 10,780 ± 140 K and

When Flux Standards Go Wild: White Dwarfs in the Age of Kepler

\mathrm{log}\,g

White Dwarf Rotation as a Function of Mass and a Dichotomy of Mode Line Widths: Kepler Observations of 27 Pulsating DA White Dwarfs through K2 Campaign 8

= 7.94 ± 0.08, shows outbursts recurring on average every 5.0 days, increasing the overall flux by up to 15%. EPIC 229227292, with

Rapid Evolution of the Gaseous Exoplanetary Debris around the White Dwarf Star HE 1349–2305

{T}_{\mathrm{eff}}

A 15.7-Minute AM CVn Binary Discovered in K2

= 11,190 ± 170 K and

Destroying Aliases from the Ground and Space: Super-Nyquist ZZ Cetis in K2 Long Cadence Data

\mathrm{log}\,g

Evidence from K2 for rapid rotation in the descendant of an intermediate-mass star

= 8.02 ± 0.05, has outbursts that recur roughly every 2.4 days with amplitudes up to 9%. We establish that only the coolest pulsating white dwarfs within a small temperature range near the cool, red edge of the DAV instability strip exhibit these outbursts.

The magnetic cataclysmic variable LSQ1725-64

SGP acknowledges the support of the Leverhulme Trust. The research leading to these results has received funding from the European Research Council under the European Unions Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement numbers 340040 (HiPERCAM) and 320964 (WDTracer), as well as the European Unions Horizon 2020 Research and Innovation Programme/ERC Grant Agreement number 677706 (WD3D). ULTRACAM, and TRM, VSD and SPL are supported by the Science and Technology Facilities Council (STFC) under grants ST/L000733 and ST/M001350. DAHB is supported by the National Research Foundation of South Africa. Support for this work was provided by NASA through Hubble Fellowship grant #HST-HF2-51357.001-A, by NASA K2 Cycle 4 Grant NNX17AE92G, as well as NSF grants AST-1413001 and AST-1312983. This work has made use of data obtained at the Thai National Observatory on Doi Inthanon, operated by NARIT; the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministerio da Ciencia, Tecnologia, e Inovacao da Republica Federativa do Brasil, the U.S. National Optical Astronomy Observatory, the University of North Carolina at Chapel Hill and the Michigan State University; and the McDonald Observatory of the University of Texas at Austin; as well as the SALT, through DDT programme 2016-2-DDT-006, where the assistance of Marissa Kotze is acknowledged. Data for this paper have been obtained under the International Time Programme of the CCI (International Scientific Committee of the Observatorios de Canarias of the IAC) with the GTC operated on the island of La Palma in the Observatorio del Teide/Roque de los Muchachos.