ASASSN-19de (TCP J06373299-0935420)

[Robin Leadbeater]

This normally 19th mag star in Monoceros is currently at mag 10.3 (g) and still brightening. An R~500 ALPY spectrum taken last night shows a blue continuum with no H alpha line and H beta and higher Balmer lines in weak absorption. The spectrum can be viewed here

https://britastro.org/specdb/data_graph.php?obs_id=3925

and a current light curve and finder image is available here on the ASASSN website

https://asas-sn.osu.edu/light_curves/d99aa5e7-0b3f-4127-afbe-cd34192b0a67

Robin

[David Swan]

Hi Robin. Very interesting. Am I right in thinking this would be consistent with an accretion disk in an optically thick state? Or are there other – perhaps more likely – explanations?

[Robin Leadbeater]

Hi David,

I’m afraid I am not enough of an expert to interpret spectra of CVs, beyond being able to tell the difference between the spectrum of a classical nova and one of a dwarf nova. This is a typical spectrum of a dwarf nova in outburst. In this case a large amplitude outburst of a star with no previous history of outbursts so a likely WZ Sge (UGWZ)  type (I am reliant on Patrick Schmeer for this classification)

The source of the additional flux is impressively hot. The continuum fits to a ~35000K Planck curve, like an O star

Robin

[Nick James]

Here’s an image of it from last night. I get it to be 10.68 (using Gaia G and the green plane of this colour image)

[David Swan]

Here’s another image. As Nick’s image shows, and indeed Robin’s spectrum indicates, the object is very blue. I’ve uploaded a higher quality image to my member’s page.

[Robin Leadbeater]

Another spectrum last night. It has cooled significantly (to ~15000K) and the Balmer absorption lines are more pronounced

Robin

[Author]

Posts