AN Ursae Majoris

AN Ursae Majoris

A light curve for AN Ursae Majoris. The main plot (from Catalina Sky Survey data[1]) shows the long term variation, and the inset plot (from TESS data[2]) shows the variation over the orbital period.
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ursa Major
Right ascension 11h 04m 25.65570s[3]
Declination +45 03 13.9415°[3]
Apparent magnitude (V) 14.9 – 20.2[4]
Characteristics
Spectral type pec(e+cont)[4]
Variable type Eclipsing + Polar[4]
Astrometry
Proper motion (μ) RA: −44.989[3] mas/yr
Dec.: −24.972[3] mas/yr
Parallax (π)3.0993 ± 0.1371 mas[3]
Distance1,050 ± 50 ly
(320 ± 10 pc)
Orbit[5]
Period (P)0.0798 d
Eccentricity (e)0.00
Periastron epoch (T)2,444,217.9961 JD
Argument of periastron (ω)
(secondary)		0.00°
Semi-amplitude (K1)
(primary)		321 km/s
Details
White dwarf
Mass0.4–0.6[6] M☉
Temperature≈ 20,000[6] K
Other designations
AN UMa, PG 1101+453,[7] S 07738, X 11016+454[4]
Database references
SIMBADdata

AN Ursae Majoris is a binary star[5] system in the northern circumpolar constellation of Ursa Major. It is a variable star, with AN Ursae Majoris being the variable star designation, and ranges in brightness from 14.90 down to 20.2.[4] Even at its peak brightness though, the system is much too faint to be visible to the naked eye. Based on parallax measurements, the system is located roughly 1,050 light years away from the Sun.[3]

This is a single-lined spectroscopic binary system with a period of 1.92 hours in a close, circular orbit.[5] The pair form an eclipsing binary system that decreases from magnitude 14.9 down to 20.2, once per orbit.[8] This object, along with AM Herculis, define a class of cataclysmic variables known as polars.[9] The pair consist of a low mass white dwarf with a strong magnetic field, interacting with a low–mass main sequence star that has filled its Roche lobe. Matter is being energetically accreted from the main sequence star onto one or both magnetic poles of the white dwarf star, producing emission lines in the spectrum. The magnetic field of the white dwarf has an estimated strength of 35.8 MG.[6]

  1. ^ Cite error: The named reference Catalina was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference MAST was invoked but never defined (see the help page).
  3. ^ a b c d e f Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  4. ^ a b c d e Cite error: The named reference Samus2017 was invoked but never defined (see the help page).
  5. ^ a b c Cite error: The named reference Schneider1980 was invoked but never defined (see the help page).
  6. ^ a b c Cite error: The named reference Sanad2015 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Avvakumova2013 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Krzeminski1977 was invoked but never defined (see the help page).