1RXS J232953.9+062814 : New SU UMa star with a ultrashort period

P. Schmeer reported an outburst of this recently discovered dwarf nova at 12.5mag on November 3 (vsnet-campaign 1205). The Kyoto team performed time-series observation on November 4 (vsnet-campaign 1206), and detected strong humps with a very short period of 0.043 day (vsnet-campaign 1208). As also confimed by T. Vanmunster on Novemver 5/6, this object turned out to be a new SU UMa star below the period minimum (vsnet-campaign 1211, 1212, 1213). According to Jingyao et al (1998), The outburst spectrum resembles that of an A-star. The quiescent spectrum was dominated by Balmer and He I emission lines, indicating that the object is not hydrogen-poor (vsnet-campaign-dn 1844). The Gunma team performed spectroscopy and reported a spectra with weak absorption lines of H-beta, H-gamma and H-delta, and the H-alpha emission (vsnet-campaign-dn 1861). B. Skiff reported a proper motion of this object to be 0"".049/yer using USNO-A2.0 and GSC-2.2 catalogues (vsnet-campaign-dn 1851). H. Yamaoka also reported to be 0".05 - 0".06 /yr using the Kyoto images (vsnet-campaign-dn 1857). The superhump period was calculated to be 0.046330(10) d (vsnet-campaign-dn 1854). T. Kato reported a period increase of superhumps. The mean period derivative is dot{P}/P = 6x10^(-5) (vsnet-campaign-dn 1859). The amplitude of humps became smaller with time, and on November 7, the object rapidly faded (vsnet-campaign 1219). The fading rate became gradual on November 9 (vsnet-campaign-dn 1864). On late November 9, the object experienced a rebrightening reaching 13.0mag (vsnet-campaign 1220). During this rebrightening, T. Vanmunster detected superhumps as in the plateau phase (vsnet-campaign 1223). It has faded with the duration of about 1 day (vsnet-campaign-dn 1876). T. Kato commented that the persistence of superhumps is similar to ER UMa stars (vsnet-campaign-dn 1879). The D. Starkey's data on the fading phase show a slightly shorter periodicity of 0.04608(4) d, indicating a possible orbital modulations (vsnet-campaign-dn 1880). It showed superhumps and sometimes double humps after the rebrightening (vsnet-campaign-dn 1885). Using the data on November 13 and 14, the period analysis yielded 0.04591(8) d, which is 0.8% shorter than the superhump period. The emergence of a significantly different period is highly suggestive of the (co-)existence of orbital modulations (vsnet-campaign-dn 1888). The superhump signal became weak on November 16 (vsnet-campaign-dn 1899). The light curve was then dominated by double-wave humps, with occasional brightenings (time scale ~1-2 hr), during which humps tend to become rather unclear (vsnet-campaign-dn 1921). The later light curve on November 19 - 21 showed two periodicity of 0.044590(16) d and 0.045935(67) d. The former probably corresponds to orbital periods, and the latter is superhumps (vsnet-campaign-dn 1935).

Both observations by the Kyoto team and T. Krajci detected a small rebrightening started on December 2. The rising rate was relatively slow, and the object became 0.15mag brighter on the monotonous gradual decline trend on December 2 - 3. After this peak, its fading rate returned to the monotonous gradual trend before the rebrightening (vsnet-campaign 1237).

Superhump light curve by the Kyoto team

Image during the outburst by the Kyoto team

Other related articles: vsnet-campaign 1209, 1214, 1215, 1216, 1218, 1220, 1224, 1225, vsnet-campaign-dn 1853, 1875, 1843, 1845, 1847, 1850, 1852, 1858, 1860, 1863, 1877, 1878, 1884, 1885, 1892, 1893, 1903

VSNET web page: http://www.kusastro.kyoto-u.ac.jp/vsnet/DNe/J2329.html