(ORDO NEWS) — Using the Hubble Space Telescope (HST), astronomers at Villanova University analyzed spectroscopic observations of a nearby star known as T Aurigae.
The results of this study, published on March 29 on the arXiv preprint server, provide a better understanding of the properties of this object.
A nova is a star that experiences a sudden increase in brightness and then slowly returns to its original state, a process that can take many months. Such an outburst is the result of an accretion process in a close binary system containing a white dwarf (WD) and its companion.
Cataclysmic Variables (CVs) are binary star systems consisting of a primary WD star that accretes matter from a normal companion star. They irregularly increase their brightness by a large amount and then return to a dormant state.
T Aurigae is a CV consisting of an HD in a compact binary with a main-sequence donor star. In 1891, a classical nova exploded in the constellation Auriga, becoming the first nova to be observed spectroscopically. The distance to T Aurigae is estimated at 2,650 – 2,840 light years.
Recently, a team of astronomers led by Conor Larsen at Villanova University have been exploring T Aurigae using data from the Hubble Space Telescope Imaging Spectrograph (STIS).
“We extracted data from the Hubble spectrograph from the MAST archive, which were obtained during the rest interval on March 7, 2003,” the researchers write in their paper.
After analyzing the spectrum of T Aurigae, Larsen’s team concluded that it was a nova dominated by an accretion disk.
This hypothesis was confirmed by the scintillation present in the light curve and the model fit performed by the scientists. It has been noted that accretionary light from the disk fully explains the observed luminosity of this nova.
The results show that the white dwarf in T Aurigae has a mass of about 0.7 solar masses and a mass transfer rate of about 0.000000018 solar masses per year. The distance to the new star was determined to be 2,738 light years.
The slope of the system was measured and was approximately 60 degrees. Astronomers suggest that for such a tilt, part of the accretion disk, possibly a hot spot, must be eclipsing.
The spectroscopic study also revealed deep metal absorption lines in the spectrum of T Aurigae. The authors of the article noted that they cannot form in the disk and most likely form in the material above the disk in the circular substance.
Another plausible scenario is that they formed in a shell ejected from the 1891 explosion. Further research is needed to confirm any of these hypotheses, especially spectroscopic observations of this system in the far ultraviolet.
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