Recently, our school astronomy department postdoctoral Su Jie and professor Fu Jianning, based on Chinese large scientific devices Guo Shoujing telescope (LAMOST) survey data of the white dwarf star observation table, found four new DA type pulsating white dwarf.
A white dwarf star is the evolution of low mass stars in late stage, is composed of a compact object electron degenerate matter. Because of the Milky Way in about 98% of the stars will eventually become a white dwarf, so the study of the white dwarf's knowledge and understanding of stellar evolution and the Milky Way system has important significance in evolutionary history, at the same time the white dwarf is a natural laboratory for research in extreme conditions of physical phenomena, and while type DA white dwarfs are the class that has thelargest number ofall known white dwarf stars. When the effective temperature of DA type white dwarf is between 12500 K and 10500 K, the whole structure of white dwarf star will vibrate, thus showing the change of brightness and becoming a pulsating white dwarf star. Through the observation and analysis of pulsating white dwarfs in the basic parameters of white dwarfs to identify and understand its internal structure. At present, the number of known DA type pulsating white dwarf is about 200, in order to have a more comprehensive study of pulsating white dwarfs character and astroseismology study, the search for a new pulsating white dwarf is very necessary.
Su Jie et al first using the stellar effective temperatures of LAMOST data tables on the white dwarf stars that has been published before, screening out of instability candidates in the band, and then use the LIJIANG 2.4 meter and XINGLONG 2.16 meter telescopes to do time-series photometric observations, to determine whether they have luminosity changes. In the recently completed work, 4 candidates were found to have significant luminosity changes that could be confirmed as pulsating white dwarfs. The figure shows the light curves of the 4 pulsating white dwarfs and the spectrum of the light curve, which shows significant light variability. This achievement is the first time a new pulsating white dwarf star has been found by Chinese astronomers relying solely on domestic observation equipment. It has good autonomy and originality.
The research results have been received by The Astrophysical Journal (ApJ), a famous international astronomical journal. (Pre-publish links: https://arxiv.org/abs/1708.07253)
The light curves and corresponding spectra of 4 newly discovered DA pulsating white dwarfs are respectively shown in the figure. Underneath Each picture is the LAMOST target catalog number. The number on the spectrogram indicates the main pulsating frequency of the pulsating white dwarf.