ER Ursae Majoris

ER Ursae Majoris

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
PG 0943+521, ER UMa, AAVSO 0939+52, GSC 03439-00550, 2MASS J09471193+5154089 [6]
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]

References

1. Zhao, Yinghe; Li, Zongyun; Wu, Xiaoan; Peng, Qiuhe; Zhang, Zhousheng; Li, Zili (April 2006), "Superhumps Behavior during Normal Outbursts in ER Ursae Majoris: Spectroscopy and Photometry", Publications of the Astronomical Society of Japan, 58 (2): 367–373, arXiv: astro-ph/0602181 , Bibcode:2006PASJ...58..367Z, doi: 10.1093/pasj/58.2.367 , retrieved 25 October 2022.
2. Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics . 649: A1. arXiv: 2012.01533 . Bibcode:2021A&A...649A...1G. doi: 10.1051/0004-6361/202039657 . S2CID   227254300. (Erratum:  doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
3. Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports , 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID   125853869.
4. Thorstensen, J. R.; et al. (April 1997), "Orbital Periods for the Unusual Dwarf Novae ER Ursae Majoris and V1159 Orionis", Publications of the Astronomical Society of the Pacific, 109: 477–482, Bibcode:1997PASP..109..477T, doi: 10.1086/133904 , S2CID   121582607.
5. Guzman, Giannina; et al. (September 2019), "FUSE and IUE Spectroscopy of the Prototype Dwarf Nova ER Ursa Majoris During Quiescence", The Astronomical Journal, 158 (3): 99, arXiv: 1907.06513 , Bibcode:2019AJ....158...99G, doi: 10.3847/1538-3881/ab322f , S2CID   196622682, 99.
6. "ER UMa". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2022-10-15.
7. Green, R. F.; et al. (June 1982), "Cataclysmic variable candidates from the Palomar Green Survey", Publications of the Astronomical Society of the Pacific, 94: 560-564, Bibcode:1982PASP...94..560G, doi:10.1086/131022, S2CID   120644760.
8. Kato, Taichi; Kunjaya, Chatief (April 1995), "Discovery of a Peculiar SU UMa-Type Dwarf Nova ER Ursae Majoris", Publications of the Astronomical Society of Japan, 47: 163–168, Bibcode:1995PASJ...47..163K.
9. Kato, Taichi; et al. (February 1996), "Large-Amplitude Superhumps in ER Ursae Majoris during the Earliest Stage of a Superoutburst", Publications of the Astronomical Society of Japan, 48: L5 –L7, Bibcode:1996PASJ...48L...5K, doi:10.1093/pasj/48.1.L5.

Further reading

• Zemko, P.; et al. (March 2014), "Study of a long and short—term variability of ER Ursae Majoris", Contributions of the Astronomical Observatory Skalnaté Pleso, 43 (3): 319–324, Bibcode:2014CoSka..43..319Z.
• Zemko, Polina; et al. (June 2013), "Detection of Change in Supercycles in ER Ursae Majoris", Publications of the Astronomical Society of Japan, 65 (3): 8, arXiv: 1212.5940 , Bibcode:2013PASJ...65...54Z, doi:10.1093/pasj/65.3.54, 54.
• Ohshima, Tomohito; et al. (August 2012), "Discovery of Negative Superhumps during a Superoutburst of 2011 January in ER Ursae Majoris", Publications of the Astronomical Society of Japan, 64 (4): L3, arXiv: 1207.2705 , Bibcode:2012PASJ...64L...3O, doi:10.1093/pasj/64.4.L3.
• Kjurkchieva, D.; Marchev, D. (September 2010), "Large-Amplitude Modulations of the Cataclysmic Star ER UMa", Publications of the Astronomical Observatory of Belgrade, 90: 147–150, Bibcode:2010POBeo..90..147K.
• Kato, Taichi; et al. (April 2003), "Unusual Phase Reversal of Superhumps in ER Ursae Majoris", Publications of the Astronomical Society of Japan, 55 (2): L7 –L10, arXiv: astro-ph/0211520 , Bibcode:2003PASJ...55L...7K, doi:10.1093/pasj/55.2.L7.
• Gao, Weihong; et al. (December 1999), "Superhumps in a Peculiar SU Ursae Majoris-Type Dwarf Nova, ER Ursae Majoris", The Astrophysical Journal, 527 (1): L55 –L59, arXiv: astro-ph/9910558 , Bibcode:1999ApJ...527L..55G, doi:10.1086/312398, PMID   10566998, S2CID   16090638.
• Szkody, P.; et al. (1996), Evans, A.; Wood, Janet H. (eds.), "IUE and Optical Spectra of RZ LMi and ER UMa Throughout their 19 and 43 Day Cycles", Cataclysmic variables and related objects. Proceedings of the 158th colloquium of the International Astronomical Union (IAU); held at Keele; United Kingdom; June 26-30; 1995, Astrophysics and Space Science Library, vol. 208, Dordrecht: Kluwer Academic Publishers, p. 55, Bibcode:1996ASSL..208...55S, doi:10.1007/978-94-009-0325-8_15, ISBN   978-94-010-6632-7, S2CID   197532794.
• Kato, Taichi; et al. (August 1995), "Photometric Detection of the Orbital Period in ER UMa", Information Bulletin on Variable Stars, 4233: 1, Bibcode:1995IBVS.4233....1K.
• Osaki, Yoji (April 1995), "A Model for a Peculiar SU Ursae Majoris-Type Dwarf Nova ER Ursae Majoris", Publications of the Astronomical Society of Japan, 47: L11 –L14, Bibcode:1995PASJ...47L..11O.
• Robertson, J. W.; et al. (May 1995), "RZ Leonis Minoris, PG 0943+521, and V1159 Orionis: Three Cataclysmic Variables with Similar and Unusual Outburst Behavior", Publications of the Astronomical Society of the Pacific, 107: 443, Bibcode:1995PASP..107..443R, doi: 10.1086/133572 , S2CID   119609461.