Affiliation
Royal Astronomical Society of New Zealand, Variable Star Section (RASNZ-VSS)
Sun, 10/07/2012 - 19:36
I'd appreciate some clarification on this star. Bateson listed it as type M: on RASNZ VSS Charts 282 and 719. Sebastian Otero notes in VSX that it was originally classified as a UG: and that the M: listing is incorrect. So is it still considered a suspected UG? It was seen on photogrtaphic plates from 1918 and 1926 by Hertzsprung. Thanks. [Stephen]
Hi, Stephen,
Yes, it is not a mira. Back then they didn't have 2MASS and other astrometric/photometric catalogues to check. There is not a red star in the area, EP Car is actually rather blue. Bluer than any of the surrounding stars and it is bright in only one out of six USNO archive plates. It is essentially constant in the rest.
So the original UG: classification is more likely, with at least two outbursts on record, the discovery observation at 13.0 p and the 1984 outburst at 15.9 R.
Here are two images one week apart showing an outburst:
http://www.aavso.org/vsx/docs/5912/133/EPCar.jpg
More observations of this star are strongly needed to detect a new maximum and confirm its classification.
Cheers,
Sebastian
Hi Stephen,
EP Car has been on my list for many years now and I have observed quite a few outbursts. There is quite a lot of data in the AAVSO data base showing these outbursts. I still have observations on EP Car yet to be entered. I have copied some information about EP Car during an outburst in 2000 in which time-resolved photometry was obtained by Gordeo Garradd. It showed some modulations simiular to superhumps.
Rod.
The dwarf nova EP Car is undergoing a relatively rare outburst.
The last outburst was observed in 2000 Feb. (mv=14.3). Time-resolved
photometry was conducted by Gordon Garradd during this outburst,
and modulations simiular to superhumps were observed. The present
outburst is relativly fainter, and rather unfavorably situated for
a long run, but further time-resolved photometry may be useful in
determining the nature of variations. We recently observed similar
modulations in some dwarf novae, e.g. V344 Ori, and their nature is
still unclear.
YYYYMMDD(UT) mag observer
20010412.446 <146 (R. Stubbings)
20010413.438 <146 (R. Stubbings)
20010413.549 <140 (P. Nelson)
20010417.517 <144 (R. Stubbings)
20010417.560 <140 (P. Nelson)
20010420.594 <150 (A. Pearce)
20010424.490 <145 (P. Williams)
20010425.506 <144 (R. Stubbings)
20010426.487 148 (R. Stubbings)
20010426.500 148 (R. Stubbings)
20010426.551 <150 (A. Pearce)
> [vsnet-alert 4238]
>
> Gordon Garradd has provieded the result from the first half of a 6-hour
> time-resolved photometry. The data seem to indicate the presense of
> 0.1-mag modulation, which might be attibuted to superhumps. The possible
> period inferred from this segment of data seems to be longer than 0.08 day.
> Further analysis of the data and observations are very promising and
> encouraging!
>
> [vsnet-alert 4245]
>
> The immediately following data by Gordon Garradd mentioned in
> [vsnet-alert 4238] have not convincingly confirmed the recurring nature
> of the hump. The object brightened again by 0.1 mag at around Feb. 17
> 14 h UT, but remained bright for at least the following two hours.
> The possibility of superhumps with a period shorter than 2 hours can be
> safely precluded, but the possibility for a longer period still remains.
> It should be worth noting no rapidly fading trend was observed during
> the entire run.
Regards,
VSNET Collaboration team