QS Telescopii

QS Telescopii is a faint, well-studied^[4] binary star system in the southern constellation Telescopium.^[7] It is composed of a white dwarf and main sequence donor star, locked into a close, circular orbit facing one another. Known as polars, material from the donor star does not form an accretion disk around the white dwarf, but rather streams directly onto it.^[6] This is due to the presence of the white dwarf's strong magnetic field. The pair undergo frequent shifts between a high and low accretion states, and it shifts between single and double accretion poles. The main pole is partially self-eclipsing.^[4]

QS Telescopii

A visual band light curve for QS Telescopii, adapted from Rosen et al. (1996)[1]
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Telescopium
Right ascension	19h 38m 35.816s[2]
Declination	−46° 12′ 57.11″[2]
Characteristics
Spectral type	M4.5±0.5[3]
Variable type	AM Her[4]
Astrometry
Radial velocity (Rv)	110 km/s
Proper motion (μ)	RA: +35.150 mas/yr[2] Dec.: −25.496 mas/yr[2]
Parallax (π)	5.3378±0.0834 mas[2]
Distance	611 ± 10 ly (187 ± 3 pc)
Orbit[5]
Period (P)	2.33 h
Eccentricity (e)	0.0
Details
White Dwarf
Mass	0.71[6] M☉
Temperature	17,500[6] K
Other designations
QS Tel, EUVE J1938-46.2, RE 1938-461, AAVSO 1931-46[7]
Database references
SIMBAD	data

The pair orbit each other with a period of 2.33^[5] hours in a circular orbit. The donor star is a small red dwarf with an estimated stellar classification of M4−5.^[3] The white dwarf primary has 71% of the mass of the Sun and an effective temperature of 17,500 K.^[6] It has a magnetic field strength of 50–80 MG. The system is a source for X-ray emission.^[4]

See also

• Variable stars
• Polar (cataclysmic variable)
• AM Herculis