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Дата изменения: Mon Jan 8 14:18:18 2007 Дата индексирования: Tue Oct 2 00:30:37 2012 Кодировка: Поисковые слова: halloween |
Fig. 1. CCD blue frames of V838 Mon before the eclipse (left)
and in the eclipse (right).
The fragment of the historical light curve of V838 Mon in the B band
given in the upper box of the Figure 2 shows the disappearance of the
both blue components of the binary. Red circles are photographic
pre-outburst observations indicating the total light of two
stars. The main outburst light curve is not shown here, only its
decay is drawn by vertical line. The blue and green
circles are CCD observations. After the main outburst
decay, we see only one B3V star (near JD~2452600). The remnant
of the explosion was then so cool, that its light did not reach
photometric B band. Later it became hotter, a small amount of flux
reached the B band, and weak brightening occured. And finaly, the
second B3V star in this system disappeared due to eclipse. The
light curve of the eclipse is shown in the bottom box. One point
given in parentheses shows an observation of poor quality published
by Bond.
Fig. 2. Fragments of the light curves of V838 Mon in the
B filter.
Fig. 3. Spectral energy distributions of V838 Mon.
It is interesting to establish the nature of residual light in
the eclipse (light-red line). Mostly this is the radiation of
cool sgL star at the long wavelength, but there is a strong
blue and UV excess superimposed on the distribution of the cool star.
Barsukova et al.
(ATel 803) reported the rapid strengthening of [FeII] forbidden-
line spectrum in the blue region what they explain with the
rarefied gas of ejecta arriving to the vicinities of B3V companion,
and this companion was the source of ionizing radiation.
This emission-line spectrum may explain the excess.
Bond (ATel 966) reported that the blue emission lines of [FeII]
continue to be strong, and very strong emission of H-alpha is
detected in his October 12, November 29, and December 13, 2006
spectra. H-alpha emission was not seen in May. The evolution
of this emission-line spectrum was accompanied by small
photometric brightening of the star by 0.13,
0.15, 0.18, and 0.20 mag in Rc,V,B, and U filters, consequently.
Bond suggested that the ejecta have reached the vicinity
of the B3V companion and are beginning to engulf the star.
Our December 19 photometry (BVRcIc observations were taken
by A.N.Burenkov in SAO) shows that the radiation of B3V star
has totally disappeared from the star energy distribution. If such a
hot star is really engulfed by the L-type supergiant and is now
located under its photosphere, the source of ionization should
disappear, and [FeII] line spectrum vanish. Otherwise, the
eclipse hypothesis does not predict disappearance of [FeII] line
spectrum, but partial eclipse of its forming region is possible.
View of current
UBVRcRjIcIj light curves of V838 Mon. Java compatible brouser is
needed. Use mouse mouseDrag function to examine the details.