I don’t know if this is previously known, but perhaps was superhumps visible in the intermediate polar HT Cam after its outburst 2023. I have not found any previously reporting about it.
HT Cam had a very short outburst 2023-02-14 (JD 2459989), only lasted 1 or 2 days. During the outburst the star raised from mag 17 to 11.5 and was observed in AAVSO by 3 visual observers and 1 photometric. After the outburst has the star continued to be a bit brighter than before the outburst, from mag. 17-17.2 to now 16.5-16.2.
I have done a period analysis from the photometric time series that was taken right after the outburst and found a variation with the amplitude 0.3 mag and the period 0.06108 days. The humps were most prominent the first 2 weeks after the outburst, but was visible up to 4 weeks after the outburst.
VSX has the period 0.059712 for HT Cam. This should be the orbital period measured spectroscopically. It has also a spin period that is about 1/10 of this period. The period I found is 2.3% higher than the orbital period and could indicate superhumps in the system.
Apart from the month after the outburst I have not found any prominent periods for the star in the region 0.05 to 0.07. The spin period on the other hand is always prominent.
I don’t know of any reports of superhumps in HT Cam, either - there are a couple of other IPs with superhumps (CC Scl, Woudt et al. CC Sculptoris: a superhumping intermediate polar - NASA/ADS and V455 And, Araujo-Betancor et al. HS 2331+3905: The cataclysmic variable that has it all - NASA/ADS) but they have true superoutbursts, whereas HT Cam doesn’t as far as I know (you noted that the 2003 outburst was short). I’m a bit surprised that such a short outburst can excite superhumps, but superhumps can do some surprising things …
I have only basic knowledge about CV’s and would like to draw attention to this event that I found curious. From AAVSO AID was HT Cam in quiescence at JD 2459987.7 (mag 16,9), probably also at 2459988.3 (<15.3), rising at 2459989.3 (13.2), in max at 2459989.6 (11.4), descending at 2459990.3 14.9 and almost back at 2459990.6 (16.1).
There are one time series during the outburst that also shows a few humps. The variation I found was in the weeks after the outburst. I thought that the amplitude and period resembles superhumps. But the type of star and other circumstances does it less probable. But if not superhumps, what was this variation which appeared and disappeared after the short outburst?
There are known cases of true (non-magnetic) SU UMa type systems exhibiting superhumps into quiescence - most famously, V344 Lyr (Still et al. 2010, ApJLett, 717, L113; a follow-up paper by Wood et al. 2011, ApJ, 741, 105 mentions other cases). This include superhumps seen in WZ Sge in what Joe Patterson described as the final decline phase (Patterson et al. 2002, PASP, 114, 721). Also, Araujo-Betancor et al. detected what they thought was a quiescent superhump in V455 And. So, the fact that your detection was back in quiescence should be okay. The remaining question, to me, is if a short outburst can indeed lead to superhumps …
I asked ChatGPT to provide references to superhumps in HT_Cam, and “it” provided the following list of positive detections dating back 29 years to the first one.
“There have been multiple studies on HT Cam and its behavior, including its outbursts and the presence of superhumps. Some key references include observations of superhumps in the light curves of HT Cam that point to the presence of an eccentric accretion disk or precessing disk.”
“Here are a few references where superhumps in HT Cam are discussed:”
Patterson, J., et al. (1998).
"Superhumps in the Nova-like Variable HT Cam."
The Astrophysical Journal, 501(1), 439-444.
This paper presents an analysis of the photometric data of HT Cam during outburst phases and discusses the detection of superhumps in the system, providing a detailed light curve and period analysis.
Warner, B., et al. (1999).
"The Nova-like Variable HT Cam and its Outbursts."
MNRAS, 309(4), 902-914.
This study provides an in-depth look at the outburst behavior of HT Cam, highlighting the role of superhumps in its light curve during active phases.
Hameury, J.-M., et al. (1998).
"The nature of superhumps in Nova-like variables."
Astronomy & Astrophysics, 334, 271-281.
While this paper discusses the theoretical models for superhumps in nova-like variables like HT Cam, it also includes observational data that confirm the presence of superhumps in systems with eccentric accretion disks, such as HT Cam.
Berriman, G. B., et al. (1995).
"Superhumps in HT Cam: a study of accretion disk geometry in nova-like variables."
The Astronomical Journal, 110(5), 2486-2492.
This paper reports on photometric observations of HT Cam, identifying superhump periods and linking them to the precessing accretion disk model.
“These references offer a combination of theoretical understanding and observational data on the occurrence of superhumps in HT Cam, helping to connect the phenomenon to the system’s disk structure and outburst properties. For more detailed and up-to-date research, checking the original papers through sources like ADS (NASA’s Astrophysics Data System) or arXiv could be useful.”
Unfortunately, these are all non-existent papers made up by ChatGPT - what AI people prefer to call “hallucinations.” (Anybody can do their own ADS searches to verify this.) Perhaps ChatGPT clued off on the similarity in name between HT Cam, the low luminosity intermediate polar in which a superhump would be unusual, and HT Cas, the well known, deeply-eclipsing SU UMa-type dwarf nova whose superhumps are well studied.
One clue: HT Cam was originally discovered as a ROSAT X-ray source, RX J0757.0+6306, and its variable star designation (HT Cam) was not given until the 75th name list originally published on 2000 March 31 (http://ibvs.konkoly.hu/pub/ibvs/4801/4870.pdf).
Very illustrative example of to be careful of what ChatGPT and other AI systems say. I was at first confused as to why I hadn’t seen any of those articles before when I searched on info about HT Cam.
Yes, none of the references that ChatGPT cited actually exists. A study of even these few which is focused on which parts are real and which parts are not reveals a good deal about how ChatGPT works to produce such responses to queries. I thought that I might describe some of that in a post here, but it is too complex and way far off-topic. Calling the responses to questions “hallucinations” is ChatGPT’s way of dodging the fact that their AI evidently and too frequently only fabricates plausible fictions … entertaining, perhaps, but otherwise not useful. Other participants in the AI industry can, however, generate useful applications that are more firmly grounded in this world.
