A visual band light curve for ER Ursae Majoris. The main plot shows a normal outburst in 2004, with the estimated value for the unobserved maximum plotted in red. The inset plot shows superhump oscillations. Adapted from Zhao et al. (2006). [1] | |
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Ursa Major |
Right ascension | 09h 47m 11.941s [2] |
Declination | +51° 54′ 08.95″ [2] |
Apparent magnitude (V) | 12.4 to 15.2 [3] |
Characteristics | |
Variable type | Dwarf nova(?) [3] |
Astrometry | |
Proper motion (μ) |
RA: 33.659
mas/
yr
[2] Dec.: −6.209 mas/ yr [2] |
Parallax (π) | 2.8039 ± 0.0205 mas [2] |
Distance | 1,163 ± 9
ly (357 ± 3 pc) |
Orbit [4] | |
Period (P) | 0.06366±0.00003 d |
Eccentricity (e) | 0.00 (assumed) |
Inclination (i) | 18–50 [5]° |
Periastron epoch (T) | 2,449,740.0637±0.0008 HJD |
Argument of periastron (ω) (secondary) | 0.00 (assumed)° |
Semi-amplitude (K1) (primary) | 48±4 km/s |
Details | |
White dwarf | |
Mass | 1.0±0.2 [5] M☉ |
Temperature | 32,000 [5] K |
Donor star | |
Mass | 0.10 [5] M☉ |
Other designations | |
Database references | |
SIMBAD | data |
ER Ursae Majoris is a variable star in the northern circumpolar constellation of Ursa Major, abbreviated ER UMa. It is a prototype system for a subclass of SU Ursae Majoris dwarf novae. [5] The system ranges in brightness from a peak apparent visual magnitude of 12.4 down to 15.2, [3] which is too faint to be visible to the naked eye. The distance to this system, based on parallax measurements, is approximately 1,163 light years. [2]
This system was identified as an ultraviolet excess object as part of the Palomar-Green (PG) survey by R. F. Green and associate in 1986. It was given the catalog identifier PG 0943+521, and was confirmed to be cataclysmic variable. In 1992, it was determined this is a dwarf nova that ranges in brightness from magnitude 12.3 down to 15.2. F. A. Ringwald in 1993 found a candidate orbital period of 0.1997 days based on radial velocity variation, but with some uncertainty. [7]
In 1995, T. Kato and C. Kunjaya confirmed this is a SU Ursae Majoris-type dwarf nova, and noted the unusual nature of this system, finding it has a long superoutburst lasting about 20 days and the supercycle (the time between superoutbursts) is very short at around 43 days. [8] Large amplitude superhumps were found to occur near the start of a superoutburst, with a brightness increase of around 0.35 magnitude. [9] The properties of the system suggest a high mass transfer rate and the white dwarf component is hotter than in other typical dwarf novae. During periods of quiescence, the accretion rate is 7.3×10−11 M☉·yr−1. [5]
A visual band light curve for ER Ursae Majoris. The main plot shows a normal outburst in 2004, with the estimated value for the unobserved maximum plotted in red. The inset plot shows superhump oscillations. Adapted from Zhao et al. (2006). [1] | |
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Ursa Major |
Right ascension | 09h 47m 11.941s [2] |
Declination | +51° 54′ 08.95″ [2] |
Apparent magnitude (V) | 12.4 to 15.2 [3] |
Characteristics | |
Variable type | Dwarf nova(?) [3] |
Astrometry | |
Proper motion (μ) |
RA: 33.659
mas/
yr
[2] Dec.: −6.209 mas/ yr [2] |
Parallax (π) | 2.8039 ± 0.0205 mas [2] |
Distance | 1,163 ± 9
ly (357 ± 3 pc) |
Orbit [4] | |
Period (P) | 0.06366±0.00003 d |
Eccentricity (e) | 0.00 (assumed) |
Inclination (i) | 18–50 [5]° |
Periastron epoch (T) | 2,449,740.0637±0.0008 HJD |
Argument of periastron (ω) (secondary) | 0.00 (assumed)° |
Semi-amplitude (K1) (primary) | 48±4 km/s |
Details | |
White dwarf | |
Mass | 1.0±0.2 [5] M☉ |
Temperature | 32,000 [5] K |
Donor star | |
Mass | 0.10 [5] M☉ |
Other designations | |
Database references | |
SIMBAD | data |
ER Ursae Majoris is a variable star in the northern circumpolar constellation of Ursa Major, abbreviated ER UMa. It is a prototype system for a subclass of SU Ursae Majoris dwarf novae. [5] The system ranges in brightness from a peak apparent visual magnitude of 12.4 down to 15.2, [3] which is too faint to be visible to the naked eye. The distance to this system, based on parallax measurements, is approximately 1,163 light years. [2]
This system was identified as an ultraviolet excess object as part of the Palomar-Green (PG) survey by R. F. Green and associate in 1986. It was given the catalog identifier PG 0943+521, and was confirmed to be cataclysmic variable. In 1992, it was determined this is a dwarf nova that ranges in brightness from magnitude 12.3 down to 15.2. F. A. Ringwald in 1993 found a candidate orbital period of 0.1997 days based on radial velocity variation, but with some uncertainty. [7]
In 1995, T. Kato and C. Kunjaya confirmed this is a SU Ursae Majoris-type dwarf nova, and noted the unusual nature of this system, finding it has a long superoutburst lasting about 20 days and the supercycle (the time between superoutbursts) is very short at around 43 days. [8] Large amplitude superhumps were found to occur near the start of a superoutburst, with a brightness increase of around 0.35 magnitude. [9] The properties of the system suggest a high mass transfer rate and the white dwarf component is hotter than in other typical dwarf novae. During periods of quiescence, the accretion rate is 7.3×10−11 M☉·yr−1. [5]