Variable binary star system in the constellation Ursa Major
ER Ursae Majoris
A
visual bandlight 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]
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
amplitudesuperhumps 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 7.3×10−11M☉·yr−1.[5]
^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,
S2CID121582607.
^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,
S2CID120644760.
^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.
^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.
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.
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,
ISBN978-94-010-6632-7,
S2CID197532794.
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,
S2CID119609461.