10 Feb 2016

Variable Star alert V694 Monoceros

Star: V694 Mon
RA 07h 25m 51.28s DEC -07 44’ 08.09”
Click on images to enlarge.
Astronomers at the INAF-Osservatorio Astronomico di Padova in Italy are studying the unique symbiotic binary V694 Monoceros which is now on a steep rise in brightness. Indications are that it is about to surpass the record level attained during the last, and much studied, outburst of 1990, which was the brightest event in the historical light-curve of the object. At that time V694 attracted special interest by showing deep and broad absorptions, blue-shifted by 6000 km/s and completely detached from corresponding emission lines, as if originating in discrete blobs, ejected from the central star and rapidly accelerated to large velocities.
These absorptions have shown considerable variability in intensity, profile and velocity over the years. These latest measurements for February 5.967 UT shows V694 at Mag 8.88. For comparison, the peak brightness in 1990 was reached at Mag 9.2.
On February 5 the astronomers collected spectra on V694, in low resolution with the Asiago 1.22m telescope and in high resolution Echelle mode with the Multi Mode Spectrograph on the Varese 0.61m telescope. On top of an A-type hot continuum (with Balmer continuum in absorption), two types of absorption and two types of emission lines were observed. The absorptions in NaI D1-D2, CaII H-K, HeI 5876, and FeII multiplet 42 are located at -1900 km/s, 200-300 km/s wide, with a round profile and are completely detached from the corresponding emission lines.
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