[vsnet-campaign-ip 121] Call for Observation: Campaign for outbursts of intermediate polars

[Makoto Uemura]

CALL FOR OBSERVATION 

Optical Campaign for Outbursts of Southern Intermediate Polars 
--- Prompt Spectroscopy with Cerro Tololo 1.5-m Telescope ---
***** August - December 2005 *****

http://home.hiroshima-u.ac.jp/~uemuram/ipoutburst2005/index.html

1. Overview
2. Targets and Strategy
3. Short summary of scientific backgrounds

1. Overview

    We have got 17-hour ToO (Target of Opportunity) time of 
Cerro Tololo 1.5-m telescope during August 1 - December 23, 2005.  
This ToO is aimed at prompt spectroscopy during outbursts of 
intermediate polars (IPs).  We'd like to call for observations 
of our targets in order to monitor the targets and promptly trigger 
the ToOs.  If you have an interest to our project, please let me 
know (uemuram at hiroshima-u.ac.jp). 
    We are planning another ToOs for northern IPs and fainter IPs 
with other telescopes in future.  This is the first step for 
the project.


2. Targets and Strategy

    All IPs can be our targets when they start very rare and 
unprecedented outbursts.  
    The list below is our recommended targets, which have 
experienced IP or IP-like outbursts before. 
    We'd like to ask collaborators to monitor these objects 
as frequently as possible, and when an outburst occurs, to 
report us promptly.

Class 1 (higher priority):  
  TV Col:  dq, 05:29:25.44, -32:49:04.5, 13.6V - 14.1V
            Short outbursts with a low amplitude.

Class 2 (lower priority):
  CW Mon:  ug, 06:36:54.53, +00:02:16.3, 11.9v - 16.3v
            Atypically rapid decline from outbursts.  IP?

  RX J0944.5+0357: dq, 09:44:31.72, +03:58:05.4, 12.8-16.3B
            Rapid decline from dwarf nova outbursts.

  NSV10934: ugsu, 18:40:52.61, -83:43:08.6, 11.2p - <15.0p
            Atypically rapid decline from normal outbursts.  IP?
            Only normal outbursts will be a target for the ToO.

  GZ Cnc: ug/dq:, 09:15:51.70, +09:00:50.2, 13.1p - 15.4p
            Clustering of outbursts.  IP?

  AH Eri: ug/dq:, 04:22:38.10, -13:21:30.2, 13.5V - 18.5V
            IP candidate showing dwarf nova outbursts.

Our project requires to start ToOs as early as possible in outbursts.
When an alert of one of the above targets is reported to us, we will 
decide whether ToOs are triggered or not, based on observations 
last few days.  If there is no observation in the last few days, 
we will not trigger ToO because we cannot confirm whether we can 
observe an early phase of the outburst.  
Our ToO times is 17 hours, that is, 2 nights. 
We will carefully select the best opportunity for our goal.

You can find detailed information about target at:
http://home.hiroshima-u.ac.jp/~uemuram/ipoutburst2005/index.html

3. Short summary of scientific backgrounds

    Several IPs show outbursts, like dwarf novae.  It has been, 
however, suspected that their mechanism may be different from 
that of dwarf novae.  This is because some of IP outbursts show 
peculiar characteristics compared with dwarf novae.  
TV Col, for example, show very short outburst with a low amplitude. 
Hellier & Buckley (1993) suggested that outbursts of TV Col are 
not caused by the disk instability (a good model for dwarf novae), 
but caused by the mass-transfer instability.  

    On the other hand, recent observations have revealed that 
there are more various types in IP outbursts.  IP outbursts are 
not always "low amplitude" and "very short", like TV Col.  
HT Cam and DO Dra, for example, show very short outbursts with 
high amplitudes.  While the IP outburst nature is not established, 
several dwarf novae are known to show outbursts like IP's.  
CW Mon and RX J0944.5+0357, for example, show atypically rapid 
declines from outbursts, which are reminiscent of IP outbursts.

    The final goal of our project is to understand outbursts 
of IPs and IP candidates; whether their mechanisms are same or not; 
if they are same, what causes the observed diversity of them.  
Due to their rapid time evolution, spectroscopic observations have 
poorly been reported during outbursts.  For the first step of 
this project, we now propose prompt spectroscopy during outbursts 
of southern bright IPs with the CTIO 1.5-m telescope.

Makoto Uemura
Hiroshima University, Japan
uemuram at hiroshima-u.ac.jp
Co-Investigators: R. Mennickent, S. Mineshige, T. Kato, 
D. Nogami, R. Ishioka, and A. Imada