Related papers: White-dwarf asteroseismology with the Kepler space…
The current picture painted by the observations of circumstellar dust at white dwarfs, and the consequent atmospheric pollution, is of a surviving planetary system. This chapter recounts in detail both the discovery and empirical…
Many low-mass white dwarfs are being discovered in the field of our galaxy and some of them exhibit $g$-mode pulsations, comprising the extremely low-mass variable (ELMV) stars class. Despite it is generally believed that these stars are…
We present results from a search for short time-scale white dwarf variability using \texttt{gPhoton}, a time-tagged database of \textit{GALEX} photon events and associated software package. We conducted a survey of $320$ white dwarf stars…
For many years, astronomers interested in white dwarf stars have promised that the study of these relatively simple compact objects would ultimately lead to useful information about the physics under extreme conditions of temperature and…
Asteroseismology involves probing the interiors of stars and quantifying their global properties, such as radius and age, through observationsof normal modes of oscillation. The technical requirements for conducting asteroseismology include…
Pre-white dwarf (PWD) star evolution can be driven by energy losses from neutrino interactions in the core. Unlike solar neutrinos, these are not the by-product of nuclear fusion, but instead result from electron scattering processes in the…
White dwarfs are one of the few types of stellar objects for which we know almost nothing about the possible existence of companion planets. Recent evidence for metal contaminated atmospheres, circumstellar debris disks and transiting…
White dwarfs with infrared excess emission provide a window into the late stages of stellar evolution and the dynamics of circumstellar environments. Using data from the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX), we…
Low-mass ($M_{\star}/M_{\sun} \lesssim 0.45$) white dwarfs, including the so called extremely low-mass white dwarfs (ELM, $M_{\star}/M_{\sun } \lesssim 0.18-0.20$), are being currently discovered in the field of our Galaxy through dedicated…
High-precision and long-duration light curves from space telescopes have revolutionized the fields of asteroseismology and binary star systems. In particular, the number of pulsating systems in eclipsing binaries has drastically increased…
It is well known that asteroseismology is the unique technique permitting the study of the internal structure of pulsating stars using their pulsational frequencies, which is per se very important. It acquires an additional value when the…
The Kepler spacecraft provides new opportunities to search for long term frequency and amplitude modulations of oscillation modes in pulsating stars. We ana- lyzed nearly two years of uninterrupted data obtained with this instrument on the…
ZZ Ceti stars are pulsating white dwarfs with a carbon-oxygen core build up during the core helium burning and thermally pulsing Asymptotic Giant Branch phases. Through the interpretation of their pulsation periods by means of…
We present a prescription for parametrizing the chemical profile in the core of white dwarfs in the light of the recent discovery that pulsation modes may sometimes be deeply confined in some cool pulsating white dwarfs. Such modes may be…
Ultra-massive white dwarf stars are currently being discovered at a considerable rate, thanks to surveys such as the {\it Gaia} space mission. These dense and compact stellar remnants likely play a major role in type Ia supernova…
Oscillations occur in stars of most masses and essentially all stages of evolution. Asteroseismology is the study of the frequencies and other properties of stellar oscillations, from which we can extract fundamental parameters such as…
White dwarf spectroscopy shows that nearly half of white dwarf atmospheres contain metals that must have been accreted from planetary material that survived the red giant phases of stellar evolution. We can use metal pollution in white…
We present an asteroseismic analysis of the helium atmosphere white dwarf (a DBV) recently found in the field of view of the Kepler satellite. We analyze the 5-mode pulsation spectrum that was produced based on one month of high cadence…
The measured rates of period change, $\dot{P}$, in the signals of pulsating white dwarf stars are often interpreted as direct detections of structural changes from secular cooling. Due to the intrinsic nature of this quantity, $\dot{P}$…
A central challenge in the field of stellar astrophysics lies in accurately determining the mass of isolated stars. However, for pulsating white dwarf (WD) stars, the task becomes more tractable due to the availability of multiple…