V1280 Sco (Nova Scorpii 2007)


Independently discovered on February 4, 2007 by Yuji Nakamura and Yukio Sakurai at a magnitude of about 9.7, V1280 Sco quickly established itself as one of the most interesting novae of the current century. On February 17 it reached a peak magnitude of 3.79, making it one of the brightest novae of the past few decades. From the first days after its discovery, the behavior of this nova seemed curious to observers. Its rise to maximum was unusually slow, similar to that of some slow novae. Its initial slow decline suddenly speeded up during the second week after maximum, then slowed again and demonstrated variations until it reached a temporary minimum brightness at magnitude 15 about three months after maximum.  The system then brightened unexpectedly by 3 magnitudes 104 days after maximum, and then dimmed once again, reaching a minimum of magnitude 16. It then brightened once more and is currently holding at approximately magnitude 10.5 (CBAT 2007; Chesneau et al. 2008).

This pattern of rapid dimming and sudden secondary brightening was exciting for astronomers. For the first time, they were able to watch as a shell of dust formed around the system, and finally dissipated enough to make it semi-transparent.  In addition, the two re-brightenings may have been caused by “enhanced mass loss” from the white dwarf (Hounsell 2010: 486). Using the European Space Agency’s  Very Large Telescope Interferometer (VLTI), the carbon-rich dust shell’s evolution was monitored in extreme detail at various infrared wavelengths . It is estimated that the total amount of dust shed by this system surpassed 30 earth masses (ESO 2008). The shell was also monitored in x-ray, making it “only the second carbon-rich dust-forming nova” seen at these wavelengths (Ness et al. 2009). This close study of the nova’s dust shell is not only important for scientists seeking to understand how dust is created in the universe, but also to test methods of distance determination using the expansion rate of dust shells (Chesneau et al. 2008).

Like KT Eri, V1280 was also observed by the Solar Mass Ejection Imager (SMEI).  Although the initial rise to maximum was not captured by SMEI (due to light pollution from the Sun and Jupiter), sufficient pre-maximum data was obtained to corroborate the slow rise to maximum seen by other observers. The SMEI light curve also has sufficient detail to aid astronomers in determining the precise onset of various events in the evolution of the dust shell (Hounsell, R. et al. 2010).

Due to its relatively southern declination there are only 856 observations of it in the AAVSO archive. However these observations were used by the research team monitoring the dust shell with the VLTI, once again demonstrating the importance of AAVSO observers and observations.