SN 2003aw: Helium Dwarf Nova with P=2034s

(vsnet-alert 7658)

SN 2003aw: helium dwarf nova with P=2034s

Summary posted here from VSNET messages; object of extremely timely interest. The object is (although a little faint) suitably situated for observations from any latitude. Please use the designation SN2003aw until the object receives a permant GCVS designation. The duration of the current outburst (>22 d) is significantly longer than the "canonical" superourbursts of helium dwarf novae, such as CR Boo and V803 Cen. The duration seems to more resemble that of "standstills" (cf. Kato et al. (2001) IBVS No. 5091; Kato et al. (2000) MNRAS 315, 140) or unusually active states (Kato et al. (2001) IBVS No. 5120). If the current state of "SN2003aw" corresponds to these states of CR Boo and V803 Cen, the object would undergo brighter "outbursts" (e.g. spike-like super-bright outbursts of V803 Cen) in future. The object may alternatively correspond to dwarf nova-type helium CVs with shorter outburst duty cycles, such as CP Eri and KL Dra. In any case, further observations (including confirmation of the suggested eclipses) and future systematic monitoring for outbursts are undoubtedly needed!

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Date: Sat, 1 Mar 2003 09:58:31 +0900 (JST)
From: Taichi Kato 

According to IAUC No. 8084, "SN2003aw" looks like to be a hydrogen-deficient dwarf nova resembling KL Dra = SN1998di. The duration of the current bright state suggests a superoutburst, if this type classification is correct. Further observations are naturally encouraged!

(From
vsnet-campaign-sn 565)

> SN2003aw  20030114.0  <210C  PAL
> SN2003aw  20030206.26  178C  PAL
> SN2003aw  20030210.0   176C  PAL
> SN2003aw  20030219.0   178C  PAL
> 
> # SN 2003aw (9:05:54.79, -05:36:08.6 (J2000.0), almost superimposed on
> # the nucleus (within 2")) is hosted by also a dim galaxy.  

Regards,
Taichi Kato

Date: Sun, 2 Mar 2003 11:18:35 +0900 (JST)
From: Taichi Kato 

Woudt and Warner report in IAUC No. 8085 that they detected a periodic signal of 2034s (amplitude 0.1 mag). From this peridicity and the spectroscopic description, they suggested that the object is a double- degenerate helium-transferring binary (AM CVn star). The period is supposed to reflect superhumps. Woudt and Warner also reported the existence of shallow eclipses. If this feature is confirmed, the object is the first AM CVn star with eclipses (please note that there have been arguements whether AM CVn stars are binaries or single stars; the unambiguous identification of eclipses will present the final conclusion). There is, however, slight diference of the outburst behavior of this object from the other "dwarf nova-type" AM CVn stars, particularly in its long duration of outburst. This difference also needs to be clarified by further observations. We therefore request further follow-up observations, although the object is a bit faint (V = 18.3).

Regards,
Taichi Kato
VSNET Collaboration team

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