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(cba:news) Periods in freshly erupted novae (Joe Patterson) [2021-08-13T10:03:42Z]

For those of you not subscribing to ATEL, here's the notice we just put out, based on the CBA data so far. The star is now magnitude 15.2, and still of very high importance. It's strange to see these signals - quite common signatures of CVs in their normal states - showing up in so bright a star, with very bright and presumably large unpulsed light sources (a still-young nova!) still present to dilute the pulsed fraction.
This will mutate into a (much) more complete ApJ submission by October 1, with all the CBA contributors as named co-authors.
If we are to understand this, we need to do a much better job studying the light curves of freshly-erupted novae. "Freshly" meaning from ~20 days to ~20 years. I'll send out some suggestions in a few days. For starters, consider these: V1974 Cyg, V1500 Cyg, V1494 Aql, QU Vul, V Per. A motley crew, but likely very interesting if you can go that faint. 

joe



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The Astronomer's Telegram http://www.astronomerstelegram.org 

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ATEL #14856							     ATEL #14856

Title:	The Orbital and Pulse Periods of V1674 Herculis
Author:	J. Patterson (Columbia Univ.), M. Epstein-Martin (Columbia
		Univ.), T. Vanmunster (CBA-Belgium), J. Kemp (Middlebury Coll.), on
		behalf of the Center for Backyard Astrophysics collaboration
Queries:	jop@xxxxxxxxxxxxxxxxxx
Posted:	12 Aug 2021; 22:24 UT
Subjects:Optical, Binary, Cataclysmic Variable, Nova, Transient

We have carried out time-series photometry of V1674 Herculis = Nova Her
2021 with the globally distributed telescopes of the Center for Backyard
Astrophysics.  During 2021 July 1 - August 10, the star displayed a strong
double-humped photometric signal at 0.15302(2) days, and another strong
signal at 8.3586(3) minutes.  The latter seems consistent with the 8.357
min signal detected in pre-outburst ZTF data by Mroz et al. (ATel #14720),
and the 8.4 min X-ray signal reported in outburst by Maccarone et al. (ATel
#14776).  Writing our two strong signals as Omega and omega, we find weaker
but clear detections at omega-Omega and omega-2Omega. This is all standard
fare for an intermediate polar (DQ Her star), although there is no precedent
for such signals in so bright a star (M_V~0), and so far above quiescence
(7 mag).  The mean orbital light curve of V1674 Her during 2021 July 1
- August 10 is shown at https://cbastro.org/the-astronomers-telegram/2021-august/ 
.  The amplitude grew significantly during this interval, when the V-band
brightness faded by 2 magnitudes.

Center for Backyard Astrophysics: https://cbastro.org/
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