AR Pav in outburst

[Jaroslav Merc]

Southern eclipsing symbiotic star AR Pav is detected in strong outburst (ASAS-SN g < 10). The star has been such bright only twice according to AAVSO LC since 1985 (in August 1989 and December 1997). The last two brightenings were detected in 2013 and 2014.

ASAS-SN light curve here: https://asas-sn.osu.edu/sky-patrol/coor ... 6da061ae29

Spectroscopic monitoring is encouraged.

[2SPOT]

Jaroslav,

Here's a spectrum taken from our setup in Chile with an Alpy 600

[Francois Teyssier]

Nice spectrum!
The Alpy is very well tuned.
Classical symbiotic outburst with notably He II very faint.
Spectrum uploaded in the database: https://aras-database.github.io/database/arpav.html

François

[Jaroslav Merc]

That is great, thank you!

I briefly summarized the information from your spectrum and from ASAS-SN photometry to an ATel: https://www.astronomerstelegram.org/?read=14837, to encourage the community to keep an eye on the object.

[Peter Velez]

I managed just over an hour on AR Pavings last night. Taken with UVEX with 600 lines/mm grating through a Planewave CDK.

Here is a plot with some of the key emissions marked. There are clear HeI emissions as well as FeII. I think there are 2 emissions of SiII as well though I couldn't match them up with any emissions at other wavelengths.

I have adjusted the grating to address the UV tonight - weather permitting.

Pete

[Peter Velez]

Here is another spectrum of AR PAV - this time in the UV.

There are clear P Cygni profiles for the Balmer lines as well as prominent HeI and FeII lines. I've marked OII at 4414.9A though I'm uncertain whether this is correct as it requires an ionisation energy above the other emission lines. Similarly there are some emissions quite close to HeII but these also require significantly higher ionization energies and so are probably not correct - I have not marked these on the plot.

This will be another fun target to monitor. I'll post again when the clouds clear next

Pete

[Peter Velez]

Here is a quick update on the AR Pav outburst.

This represents only 40 minutes exposure from last night - again, taken with a UVEX 600 lines/mm grating on a CDK 12.5.

I've marked most of the same emission lines as last week's spectrum (I've committed a few of the Fe II as the plot gets busy). The clear difference is the increasing brightness of the UV and blue continuum. The spectrum from 20 August is included to show the change.

More to come in a few days.

Pete

[Peter Velez]

I've continued to monitor the outburst of AR Pav. All observations were taken with UVEX with 600 lines/mm grating on a PW CDK 12.5. I have switched the grating angle a couple of times which has meant that not all observations are directly comparable. That said, there is a reasonable spread of data to look at now. Perhaps I could have been more patient and stayed with a single range of wavelengths.

The Balmer lines for early spectra had significant P Cygni profiles. Here is a comparison of data taken on 20 and 31 August 2021. The absorption component have now gone.

He I emissions are increasing in intensity. This can be seen from the comparison of spectra taken on 19 August and 1 September.

What I found interesting was the rapid increase in brightness in the blue. I've attached a plot of observations made on 21, 27, 28 and 31 August 2021. The blue continuum has jumped substantially in the period 21 to 27 August and has since dropped rapidly back. I've processed these data several times to make sure that I haven't made an error with the instrument response but come back to the same result. ASAS-SN photometry reports a small increase in brightness in the g filter from 10.23 on 21 August to 9.92 on 21 August and then back to 10.37 on 28 August. These don't match my observations - they are 0.4 of a Julian Day behind my spectra.

If anyone has an explanation I'd love to hear it. The most likely is pilot error with processing.

Lastly, I attach the full spectrum for 1 September 2021 that I have annotated (the comparison to 19 August was cropped to ensure they were comparable). Apart from the Balmer lines, Fe II remains prominent as are emissions from Ni II and Si II. The He I emissions are growing and I have detected a modest bump at 6527 which matches He II. The other lines are my best guess and may require revision.

Pete

[2SPOT]

Our last AR Pav spectrum from Chile this morning



And evolution in one month



We see in particular the evolution on small emissions lines

[Francois Teyssier]

Rod Stubbings (Tetoora Road Observatory,Victoria, Australia - http://rodstubbingsobservatory.wordpress.com/
kindly provides his photometric monitoring, showing that AR Pav is in deep eclipse.

Of course, spectra are welcome: https://aras-database.github.io/database/arpav.html