Novae. Close binary systems with orbital periods
from 0.05 to 230 days. One of the components of
these systems is a hot dwarf star that suddenly,
during a time interval from one to several dozen or
several hundred days, increases its brightness by
7-19 mag. in V, then returns gradually to its former
brightness over several months, years, or decades.
Small changes at minimum light may be present.
Cool components may be giants, subgiants, or
dwarfs of K-M type. The spectra of novae near
maximum light resemble A-F absorption spectra
of luminous stars at first. Then broad emission
lines (bands) of hydrogen, helium, and other
elements with absorption components indicating
the presence of a rapidly expanding envelope
appear in the spectrum.
As the light decreases, the composite spectrum
begins to show forbidden lines characteristic of
the spectra of gas nebulae excited by hot stars.
At minimum light, the spectra of novae are generally continuous or resemble the spectra of Wolf-
Rayet stars. Only spectra of the most massive systems show traces of cool components. Some
novae reveal pulsations of hot components with periods of approximately 100 s. and amplitudes of
about 0.05 mag. in V after an outburst. Some novae eventually turn out to be eclipsing systems.
According to the features of their light variations, novae are subdivided into fast (NA), slow (NB),
very slow (NC), and recurrent (NR) categories.
AAVSO Alert 383: March 27, 2014
Koichi Nishiyama (Kurume, Japan) and Fujio Kabashima (Miyaki, Japan) report their discovery
of a transient in Scorpius: They confirmed the discovery on unfiltered CCD frames taken around
2014 Mar 26.86981 UT. Survey frames from 2014 Mar 22.819 UT (limiting mag.= 12.5) and
23.836 UT (limiting mag.= 12.9) show no object, nor does DSS or USNO-B1.0.
The nearest star in the DENIS Database has position end figures 46.861s, 30.48", distance
0.44", magnitude I=14.222.
ATel #6015 (E. Kuulkers et al.) reports that Swift observations taken only hours after the
discovery (March 27 03:39-03:51 and 04:42-04:51 UT) reveal a new, bright, X-ray source. The
source is also seen in UVOT, with uvw1 magnitudes of 12.58 +/- 0.02 and 12.61 +/- 0.02, for the
2 snapshots, respectively. The positions they derive are consistent with the optical discovery
The mean X-ray spectrum is consistent with an (expanding) shell in a nova. The position was
covered during an XMM-Newton slew on UT 2011 March 4, but no source was seen with a 0.2-12
keV 2-sigma upper limit of 0.54 c/s. Follow-up Swift ToO observations for the next days have been
Hills Observatory: 1 January 2013 to 6 May 2018