Affiliation
American Association of Variable Star Observers (AAVSO)
Tue, 07/20/2021 - 18:54
AAVSO Alert Notice 747 announces an observing campaign on the WZ Sge-type cataclysmic variable V627 Peg. Please see the notice for details and observing instructions.
There are threads for this campaign under the following forums:
- Campaigns and Observation Reports: https://www.aavso.org/v-627-peg-campaign
- Cataclysmic Variables: https://www.aavso.org/v-627-peg-campaign-01
- Spectroscopy: https://www.aavso.org/v-627-peg-campaign-02
Please subscribe to these threads if you are participating in the campaign so you can be updated by the astronomer and by HQ. Join in the discussion or ask questions there!
Many thanks, and Good observing,
Elizabeth O. Waagen, AAVSO HQ
I have been following this for the past few days. here are low resolution (R~500) spectra showing the emergence of narrow emission components in the broad Balmer absorption lines as the outburst progressed
https://britastro.org/specdb/data_graph.php?obs_id=10120%2C10100%2C10097&spec_id=0&obs_observer_id=none&multi=yes&mix_flux=no&r_c=0&f_c=0&o_comment=&std_spectra_id=None&legend_pos=ne
1D fits files can be downloaded from the BAA database
Cheers
Robin
Hi all,
I'm Christian, the guy who requested your help with this target, so I just wanted to check in quickly to say hello and thank everybody who is able to contribute.
Hopefully the alert explains things well enough -- very briefly, this is kind of an exciting outburst, because V627 Peg is one of the closest WZ Sge-type dwarf novae, and -- like most of these systems -- erupts very infrequently, something like once every few years. Since the system is so nearby -- and therefore very bright in outburst -- this is a fantastic chance to follow the evolution of a WZ Sge outburst in more detail than is usually possible. In particular, high cadence photometry and even spectroscopy should be feasible even with relatively small apertures.
What we are especially interested in is the multi-wavelength evolution of the the system as it declines back into quiescence. We are currently getting X-ray and ultraviolet data with the Swift satellite observatory, and we have several radio telescopes trying to get observations that would allow us to track whether there is a jet in the system during outburst, and how this evolves. The sort of questions we'd like to answer are whether the (dis)appearance of the jet is connected to other events at other bands, e.g. the emergence of emission lines on the decline, or perhaps particular types of fast oscillations in the optical photometry, or maybe changes in the optical color of the system.
The Swift campaign will run for at least 30 days, so any data you can get over that period would be great. Spectroscopy and two-colour (B and V, say) high cadence photometry are especially encouraged for those of you who can do this. But any data will be useful in helping us to establish the optical evolution.
I'll try to check in here periodically to answer any questions that may arise, but please feel free to contact me directly as well if you need a response more quickly (c.knigge@soton.ac.uk).
Thanks!
Christian
A quick suggestion for those of you able to get spectroscopy on V627 Peg. There is a nice, bright and blue spectrophotometric standard star close to V627 Peg:
Name RA Dec V
BD+25d4655 21:59:42.02 +26:25:58.1 9.76
If you can easily grab a spectrum of that star each night as well, it should allow us to carry out a pretty nice flux calibration across all spectra.
For more info, see:
https://www.naoj.org/Observing/Instruments/FOCAS/Detail/UsersGuide/Observing/StandardStar/Spec/SpecStandard.html
Don't worry if that's not easy or possible though -- it's definitely more of an added bonus than a necessity.
Thanks!
Christian
Hi Christian,
I have been using a brighter reference but can make a comparison of this star with mine so the spectra can be brought to a common standard. For anyone trying to read the dat file from the link, the flux is in AB magnitude, not linear flux. The bin size also changes along the spectrum. (The third column is the bin size)
Cheers
Robin
Thanks for clarifying the format, Robin -- should have done that myself.
And using a brighter reference is OK. Theoretically, there is some benefit to everybody using the same reference star, but in practice, for our purposes, I don't think it's a big deal at all.
Cheers,
C
The intensity of the emission component of the Balmer lines and of the He II emission which have gradually been increasing has significantly reduced tonight. Is this expected behaviour or signs of a further outburst ? See here for a comparison of the rectified spectra
https://britastro.org/comment/10776#comment-10776
Cheers
Robin
This is actually extremely interesting behaviour -- to the best of my knowledge, there aren't really a lot of good benchmarks that could serve as reference points here. So we don't really know what to expect. I agree that this behaviour might indicate that we're about to go / in the process of going into a rebrightening. Continued spectroscopic and photometric coverage is therefore strongly encourage!
Thanks for flagging this up!