AL Com : The first superoutburst since 1995

As S. Kerr reported on May 18, the WZ Sge-type dwarf nova AL Com experienced a rare outburst at ~13.3mag. The last outburst was observed in 1995 April (vsnet-campaign 906, 907). The Kyoto team (R. Ishioka, et al.) detected a rapid (3.0mag/d) brightening and small hump-like features which may be the birth of "early superhumps" (vsnet-campaign 908). The light curve on May 19 taken by the Kyoto team shows the growth of early superhumps (vsnet-campaign 909). T. Kato performed period analysis of them and reported the best period is very slightly shorter than the orbital period, which may imply the first indication of "negative superhumps" in the earliest stage of WZ Sge-type superoutburst (vsnet-campaign 912). The early superhump became irregular with time (vsnet-campaign 916).


Early superhump profile

The data on May 19 and 22 shows 0.05672(2)d periodicity which is consistent with the orbital period and the profile of the humps has double peaks. The light curve became relatively flat since May 21. (vsnet-campaign 920). The data by Brno team on April 24 and 25 showed single peaked humps with the same period (vsnet-campaign 929). In the light curve on May 25 taken at Kyoto, humps with a possible longer period are detected (vsnet-campaign 933). G. Masi reported the detection of ~0.25mag humps with a period of 0.053 or 0.055 d (vsnet-campaign 943). On May 26, the object still showed early superhumps with small amplitude (vsnet-campaign-dn 862). The data on May 28 clearly showed the evolution of normal superhumps (vsnet-campaign 946). R. Ishioka reported that period analysis yielded 0.0581d, 2.6% larger than the orbital period using May 27 and 28 data (vsnet-campaign-dn 855). G. W. Billings' data on May 30 also showed superhumps with an amplitude of 0.26mag (vsnet-campaign-dn 869).

A temporal dip was observed since June 11 as reported by R. Ishioka (vsnet-campaign-dn 898). J. Pietz reported recovering from the dip on June 13 (vsnet-campaign 974). R. Novak also confirmed the dip and recovering and performed successful time-series observations (vsnet-campaign 975).

The Kyoto team reported that their observations on July 2, 3, and 4 confirmed that the outburst was finally terminated (vsnet-campaign-dn 969).


Light curve of the 2001 outburst

Other related articles: vsnet-campaign 911, 910, 918, 921, 922, 923, 924, 925, 928, 939, 940, 950, 959, 973, 979, vsnet-campaign-dn 796, 795, 792, 797, 802, 805, 806, 808, 810, 813, 815, 817, 818, 821, 823, 825, 826, 831, 832, 833, 839, 846, 847, 852, 856, 859, 866, 872, 875, 877, 881, 884, 885, 886, 893, 895, 900, 901, 904, 912, 915, 944, 945, 969,

Links:
VSNET page for AL Com: http://www.kusastro.kyoto-u.ac.jp/vsnet/DNe/alcom0105.html
CCD image by R. Novak: http://codel.astronomy.cz/planetka.jpg http://ada.astronomy.cz http://codel.astronomy.cz/ada/stars/alcom/alcom.html
CCD image by G. Masi: http://www.eurolink.it/comets/galaxies.html

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