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[vsnet-alert 3024] Re: Rare outburst of RX J0757.0+6306
- Date: Sun, 23 May 1999 13:49:25 +0900 (JST)
- To: vsnet-alert
- From: Taichi Kato <tkato>
- Subject: [vsnet-alert 3024] Re: Rare outburst of RX J0757.0+6306
- Sender: owner-vsnet-alert@kusastro.kyoto-u.ac.jp
Re: [vsnet-alert 3014] Rare outburst of RX J0757.0+6306
More (previous) information on this remarkable object:
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Subject: [vsnet-chat 662] RX J0757.0+6306
Date: Thu, 9 Oct 1997 12:22:48 +0900 (JST)
From: Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>
According to "Astronomical Time Series" (ed Maoz et al. 1997, Kluwer Academic
Press) p.195, Tovmassian et al. identified the ROSAT source RX J0757.0+6306
(=1RXS J075700.5+630602) as a new, ultrashort-period cataclysmic variable. The
orbital period is 75+/-1.4 min. The optical spectrum shows strong hydrogen
emission lines, resembling that of WZ Sge. Tovmassian et al. discussed in this
paper the possibility of a DQ Her type. This star may be worth monitoring for
possible future outbursts.
The paper did not mention the accurate coordinates, but watching at the ROSAT
position (07h 57m 00s.5, +63o 06' 02" 2000.0) might be sufficient.
Regards, Taichi Kato
Subject: [vsnet-chat 663] RX J0757+6306 (Tovmassian)
Date: Thu, 9 Oct 97 23:38:25 PDT
From: Gaghik Tovmassian <gag@bufadora.astrosen.unam.mx>
Dear VSNET fans,
I'm readily support Taichi's call for monitoring
RX J0757+6306. Indeed this system has all chances to
turn into another WZ Sge system or proof to be
the shortest period Intermediate Polar.
Briefly what we know about this system:
a. It is X-ray source, not much known about spectra or variability in X-rays.
b. Optical Spectroscopy indicates CV nature with prominent accretion disk
and hot spot.
c. Period derived from the S-wave radial velocity variations is
most probably 81 minutes (+/- 5 min are not excluded).
d. The limitted photometry shows no eclipsing, high amplitude flickering
light curves. On 4 ocassions out of 5, significant signal was recorded
at frequency corresponding to 8.5 min oscillations.
e. No outburst history is available at the moment.
The POSS measurments of coordinates and magnitude are as follows:
RA 07h57m01.3s DEC +63d06m01s 2000.0 16.06 (red)
The identification chart is posted to VSNET separately.
The system was reported by Tovmassian et al. in Proceedings of
Symp. dedicated to 25th aniversary of Wise observatory
"Astronomical Time Series" (ed Maoz et al. 1997, Kluwer Academic
Press) p.195
and 13th NorthAmerican Workshop on Cataclysmic Variables,
in press.
Regards, Gaghik Tovmassian
OAN, IAUNAM, Mexico
Subject: [vsnet-alert 1379] Outburst of RX J0757.0+6306
Date: Sat, 13 Dec 1997 09:42:45 +0900 (JST)
From: Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>
Outburst of RX J0757.0+6306
H. Itoh (Tokyo, Japan) communicates that the cataclysmic variable
(possible SU UMa-type or DQ Her-type) RX J0757.0+6306 is undergoing an
outburst. Recent observations:
YYMMDD(UT) mag observer
971202.672 <137 (T. Watanabe)
971202.794 <146 (H. Itoh)
971203.015 <155 (G. Poyner)
971203.674 <135 (T. Watanabe)
971204.530 <133 (T. Watanabe)
971205.667 <142 (T. Watanabe)
971205.860 <131 (H. Itoh)
971212.866 129 (H. Itoh)
Subject: [vsnet-alert 1387]
Date: Sat, 20 Dec 1997 08:05:03 -0500
From: "John R. Thorstensen" <thorsten@Dartmouth.EDU>
Hello VSNetters,
Gaghik Tovmassian (UNAM) recently called attention to
RX J0757.0+6306, for which he quoted a most likely orbital
period of 81 +- 5 minutes (vsnet-chat number 663).
The object has very strong H emission and he noted
the similarities with WZ Sge (another very short-period,
strong-lined cataclysmic). In addition the object
showed 8.5-minute oscillations in its light curve on
several occasions, suggesting the possibility of a DQ
Her classification.
I obtained spectra of this remarkable object on
December 18 and 19 UT, using the MDM 2.4-m telescope
and modular spectrograph, at 3 A FWHM resolution
from 4000 to 7500 Angstroms. The hydrogen lines are indeed
extremely strong, with H-alpha having an equivalent
width of about 200 Angstroms. HeII 4686 is not unusually
strong, with an equivalent width of 13 A, about 1/10 the strength
of H-beta. The strong H lines made it possible
to measure good radial velocities in this object, for
which I guesstimate a magnitude well fainter than 17
(see Bob Fried's observations reported below).
Discarding a few weakly-exposed spectra taken
through moonlit clouds left 67 exposures of 6
minutes each. The spectra covered a 6.79 hour range
of hour angle.
The radial velocities of the emission lines define
an unambiguous period
0.05982 +- 0.00013 days,
or
86.14 +- 0.19 minutes.
The radial-velocity curve on this period is fairly
clean (amplitude/scatter = 2.8). While daily
cycle-count aliases are present in the periodogram,
they are weak and symmetrically distributed around
the main peak. If the weather clears tonight, I may
be able to decrease the ncertainty slightly.
This period is at the upper end of Tovmassian's quoted range.
In addition, Joe Patterson (Columbia U.) passes on the following:
Robert Fried, Braeside Observatory, observed the star photometrically
for 7-hour runs on December 16 and 17. The star was near magnitude
18, and no significant periodicity was seen (to a limit of 0.07
mag) near the range of a possible orbital period (1-4 hr).
However, a significant signal was detected at 515.1+-0.3 s, with
a full amplitude of 0.06 mag.
John Thorstensen
Department of Physics and Astronomy
Dartmouth College
Subject: [vsnet-chat 989] Previous outburst of RX J0757.0+6306
Date: Tue, 23 Jun 1998 12:11:45 +0900 (JST)
From: Taichi Kato <tkato>
Previous outburst of RX J0757.0+6306
I have received preprints from the Wyoming CV group. Thanks! Among them:
A New Cataclysmic Variable RX J0757.0+6306: Candidate for the Shortest
Period Intermeduate Polar
Tovmassian et al. Astron. Astrophys. in press
According to this article, a search for 194 Sonneberg plates yielede
another positive detection of an outburst, on 1964 December 9.
Regards,
Taichi Kato
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(end VSNET quote)
The present outburst reported by P. Schmeer is the first-ever record
since the 1997 outburst reported by Itoh. High-speed photometry is
very strongly encouraged.
The further similarity of this object to WZ Sge/short-period SU UMa
stars may be illustrated by using the ROSAT catalog.
ROSAT
mv (c/s) (hardness) d
WZ Sge 15.5 0.199 0.01 0.0567
SW UMa 16.5 0.254 -0.00 0.0568
T Leo 15.7 0.659 0.03 0.0588
VY Aqr 16.6 0.086 0.00 0.059
FS Aur 16.2 0.134 0.10 0.059
V436 Cen 15.2 0.151 0.02 0.0625
BZ UMa 15.3 0.414 0.00 0.0679
GD552 16 0.182 -0.01 0.0713
RXJ0757 16.1 0.152 0.08 0.056
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