Slow dimming in the brightness of V1647 Orionis
ATel #4237; J. P. Ninan (TIFR), D. K. Ojha (TIFR), K. K. Mallick (TIFR), S. K. Ghosh (NCRA, TIFR), J. S. Joshi (TIFR), B. C. Bhatt (CREST, IIA)
on 4 Jul 2012; 10:04 UT
Credential Certification: Devendra Ojha (ojha@tifr.res.in)
Subjects: Infra-Red, Optical, Variables, Pre-Main-Sequence Star
We report a slow dimming in the brightness of the young eruptive star V1647 Ori (cf. IAUC # 9079 , # 9006 , # 8969 , # 8968 , # 8694 , # 8681 , # 8600 , # 8396 , # 8354 , # 8284 ; CBET #2647, #2104, #1596) from the long term optical and near-infrared (NIR) photometric observations, made with the 2-m IUCAA Girawali Telescope (+IFOSC spectrograph and TIFR Near Infrared Camera, TIRCAM2) at Girawali (Pune) and the 2-m Himalayan Chandra telescope (+HFOSC spectrograph and NIR camera) at Hanle (Ladakh). Typical optical magnitudes of V1647 Ori were: 2008 September 28 UT, V = 18.95+/-0.03, R = 17.01+/-0.01, I = 14.96+/-0.01; 2012 January 17 UT, V = 19.21+/-0.04, R = 17.26+/-0.02, I = 15.24+/-0.02. During the period 2009 - 2012, the source brightness shows a linear dimming trend of ~0.3 mag in R and I bands. This linear dimming trend is also present in the brightness of an Herbig-Haro object illuminated by the source. The observations during the period January - February 2012 show an increase in dimming rate, but it can be confirmed only after the source becomes visible once again in 2012. A similar trend is also seen in NIR magnitudes: 2009 October 24 UT, J = 10.71+/-0.05, H = 8.88+/-0.05, K = 7.44+/-0.02 (using NIR camera); 2011 December 04 UT, J = 11.24+/-0.1, H = 9.25+/-0.1, K = 8.08+/-0.1 (using TIRCAM2). The source brightness has therefore dimmed by ~0.5 mag in NIR bands during the period 2009 - 2011. V1647 Ori has undergone an unexpected second outburst in 2008 after the first outburst in late 2003 which lasted for ~2 years till early 2006 (Ojha et al. 2006, MNRAS, 368, 825; Aspin et al. 2009, ApJ, 692, L67; Aspin et al. 2011, AJ, 142, id:135 and references therein).
