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CCD Observations of the Outburst of V838 Mon
V1309 Sco was proposed to be a stellar merger and a common envelope transient based on the pre-outburst light curve of a contact eclipsing binary with a rapidly decaying orbital period. Using published data, I show that the period decay timescale of V1309 Sco decreased from ~1000 to ~170 yr in 6 yr, which implies a very high value of . I argue that V1309 Sco experienced an onset of dynamical mass loss through the outer Lagrange point, which eventually obscured the binary. The photosphere of the resulting continuous optically thick outflow expands as the mass-loss rate increases, explaining the ~200 day rise to optical maximum. The model yields the mass-loss rate of the binary star as a function of time and fits the observed light curve remarkably well. It is also possible to observationally constrain the properties of the surface layers undergoing the dynamical mass loss. V1309 Sco is thus a prototype of a new class of stellar transients distinguished by a slow rise to optical maximum that are driven by dynamical mass loss from a binary. I discuss the implications of these findings for stellar transients and other suggested common envelope events.
V838 Mon has been observed at the U.S. Naval Observatory, Flagstaff Station since its initial outburst in January, 2002. This paper gives a summary of the imaging activities following the discovery of the light echo in February 2002.
It was undoubtedly the rapid second outburst of V838 which increased the interest of the astronomical community in this unusual object. It is less well known that this discovery was made by a member of MEDUZA, the group of amateur observers of variable stars in the Czech Republic, who announced it quickly on the Internet and in the Czech public media. Due to its increased publicity, the star has been investigated spectroscopically with the coudé and echelle spectrographs of the Ondrejov Observatory 2m telescope. We give a short overview of the history of the discovery as well as the results of these observations.
V838 Mon has been monitored at many observatories since its initial outburst in January, 2002. This paper gives full light curves, from Johnson U through K bands, along with a description of principal events.
The peculiar nova V838 Mon has been monitored since its initial outburst in January 2002. The light curve shows several separate outbursts--a month-long hump in January, followed by a rapid 4-magnitude rise in February, two minor brightenings in March and April, and a final decline in May. This paper will discuss the current state of the nova itself, the remarkable light-echo around it, and offer some suggestions as to how amateurs can continue to monitor the object over the coming seasons.
Variable Star Network (VSNET, http://www.kusastro.kyoto-u.ac.jp/vsnet/) is a
global professional-amateur network of researchers in variable stars and
related objects, particularly in transient objects, such as cataclysmic
variables, black hole binaries, supernovae and gamma-ray bursts. The VSNET has
been playing a pioneering role in establishing the field of "transient object
astronomy", by effectively incorporating modern advance in observational
astronomy and global electronic network, as well as collaborative progress in
theoretical astronomy and astronomical computing. The VSNET is now one of the
best-featured global networks in this field of astronomy. We review on the
historical progress, design concept, associated technology, and a wealth of
scientific achievements powered by the VSNET.
In early 2002 V838 Monocerotis had an extraordinary outburst, the nature of which is still unclear. The optical light curve
showed at least three peaks, and imaging revealed a light echo around the object – evidence for a dust shell which was emitted
several thousand years ago and now reflecting light from the eruption. Spectral analysis suggests that the object was relatively
cold throughout the event, which was characterized by an expansion to extremely large radii. We show that the three peaks
in the light curve have a similar shape and thus it seems likely that a certain phenomenon was three times repeated. Our suggestion
that the outburst was caused by the expansion of a red giant, followed by the successive swallowing of three relatively massive
planets in close orbits, supplies a simple explanation to all observed peculiarities of this intriguing object.