Cataclysmic variables
 
Supernovae, novae and dwarf novae are cataclysmic events that have a devastating impact on their local area, but viewed from a distance appear as little more than a brightening point of light, usually only visible in a telescope.  Observing them challenges our imaginations, and can provide considerable information on the nature of these stars and the mechanisms in operation.  This can also help us identify candidates in our own local area...
 
This link gives a good rundown on the huge variety of cataclysmic variables:
 
 

INFORMATION:

Novae

Supernovae

Dwarf novae

______________________

LATEST NEWS:

Austral Variable Star Observers Network (membership required):

AVSON

 

Variable Stars South:

VSS

 

American Association of Variable Star Observers:

AAVSO

 

AAVSO Cataclysmic Variable Section:

CVsection

 

VSNET Alert Archives:

VSNET Alerts

 

Latest supernovae:

Supernovae

____________________
 
 
CURRENT PROJECT:
 
Monitoring known Recurrent Novae and candidate Recurrent Novae.
 
My use of a DSLR camera means that any magnitude observations I make are limited in their usefulness (acceptability) compared to CCD and visual observations.
 
The strength of DSLRs is in widefield, so I decided early in 2010 that monitoring a number of known and candidate recurrent novae would be more useful.  While the skies are well-covered by automated surveys, the earliest possible detections & notifications are crucial to gaining information on these objects, which are suspected of being progenitors of Type 1A supernovae.
 
I am monitoring V1341 LMC, CP Cru, and a number of known & candidate RNe in the Sagittarius/Scorpius region.  Well, when weather & life allow me!
 
_____________________ 
 
 
 
PREVIOUS
OBSERVING CAMPAIGNS:

Here are a few examples of observing campaigns I have contributed to, Nova Cent 2008, Nova Sco 2008 Nova Sgr 2009 No. 3, and Nova Sgr 2009 No. 4 (V5584 Sgr).  My measurements are the ones marked by red boxes in the first two, and crosses in the last two...

My method is to take unfiltered DSLR images, extract the green channel, and make visual estimates from the comparison stars marked on relevant AAVSO charts.  While not photometry, the method does seem to give reasonable correlation to V-band photometry.  Mag 12 is probably the upper limit I can reasonably go to, and I try to avoid very reddened objects where the green channel might be quite dim.
 
The correlation with V-band photometry was demonstrated in a few novae in 2009 where early observations were mainly visual, with an alarmingly wide range of magnitude estimates.  N SCT 2009 was a good example.  My estimates, aside from one seemingly anomolous obs, matched the limited V-band photometry obtained by Arne Henden and did not show the wide scatter of the visual observations:
 
 
 ____________________________
 
 
Another Dwarf Nova Outburst:
 
I don't usually follow dwarf novae, but in response to a request on vsnet-alert on 26 Sept 2010 I was able to quickly confirm an outburst of V893 Sco, a UGSU+E type variable:
 
 
V893 Sco gets as bright as mag 10.6 in outburst, but normally sits in the mid mag 14s.  It is about mag 12.0 in the above image.
 
 
 
_____________________________
 
 
My first nova image, V1280 SCO:
 
 
This was taken with a Fujifilm Finepix on tripod. 
 
 
_____________________
 
 
 
 
Other Variable Stars:
 
Reference to the AAVSO website will yield information on a huge range of variable stars.  While things that go bang interest me the most, I occasionally come across evidence of other variable stars in my shots.
 
WX SGR is an eclipsing binary (two stars orbiting each other, that eclipse each other viewed from Earth).  Here's a small animation showing maximum and minimum (mag 9.6-mag 11.3).  Minimum occurs when the dim companion eclipses the brighter star. 

 

Here's a gif animation showing an arbitrary range of high-amplitude variable stars in the Sgr, Sco and CrA region.  This was a by-product of 'blinking' recurrent novae monitoring images from May and August 2011:
 
Photobucket
 

 

 

Click on images to enlarge...

Some Images:
 
Possible nova in Carina, imaged 4 March 2012.
 
 
Possible nova in Scorpius, 8 September 2011, taken in strong moonlight.  Confirmed as a nova (Nova Scorpii 2011 No. 2) and designated V1313 Scorpii.
 
Possible nova in Lupus, 8 August 2011.  Confirmed as a nova (Nova Lupi 2011) and designated PR Lupi.
 
 V1312 Sco (Nova Scorpii 2011), 6 June 2011
 
Recurrent nova T Pyxidis in outburst, 16 April 2011, at about mag 7.8.
 

Nova Scorpii 2010 No. 2, imaged at 09:45, 2 May 2010 UT.  The nova is fading and highly reddened.

 

Recurrent nova U Sco, January 2010.  Just got the fast-dimming nova in light skies in late January.

 

Nova Scuti 2009 = V496 Scuti, 9 November 2009.  This image was taken about a day after the discovery was made.

Fourth nova in Sagittarius for 2009.  This image was taken less than 24 hours after the first of the original discovery images, taken by Koichi Nishiyama and Fujio Kabashima of Japan on October 26.439

Nova Sagittarii 2009 No. 3, 15 September 2009.  Nova is looking distinctly reddened in this colour image as it dims off.  Around mag 12.0 in this image, based on green channel (~ V band)

Canon 400D at 200mm, 3 x 75 sec.

 

From the Archive:

A nova occurs when a white dwarf star which has been accreting material from a larger companion star explosively sheds its outer layers.  We typically see this from Earth as a star brightening relatively quickly in a position where no star was known before, and dimming off again over time.

The above shots show three novae observed in 2008.  Extracting the green channel of the images, I am often able to estimate magnitudes for the novae, and have regularly submitted observations to AAVSO, who accumulate variable star data from amateur observers, for scientific use.  See examples in LH column.

 

 Novae can also be observed in nearby galaxies.  Most are quite dim when viewed from Earth of course, but occasionally novae within the Magellanic Clouds are bright enough for me to photograph.  This one is from February 2009, "Nova LMC 2009".
 

 

A supernova is a catastrophic star detonation, triggered in a variety of ways. While we're still waiting for the next Milky Way one, they go off regularly in dim & distant galaxies. Normally in the realm of big scopes & CCD cameras, sometimes when they're bright enough, all you need is an entry level DSLR and a zoom lens.  This shot was taken at 200mm in the Canon 400D.

This supernova is designated 2008bk, a Type II supernova, and the brightest one reported in 2008. It is located in the outer regions of NGC7793, a mag 10 spiral galaxy in the Sculptor group. I just find it fascinating - aside from the light from this supernova travelling for 12.7 million years before lodging on my camera sensor, what impact must this have had on the surrounding areas of NGC7793, when to us it looks for all the world like a faint MW star, and the other stars of 7793 are but a billionth part of a tiny grey fog?

 
Supernova 2011ja, 22 February 2012.  Left this a little late as it was fading off but it did get as bright as mid mag 11s earlier.  This Type IIP supernova was discovered by the veteran supernova hunter Berto Monard on 18 Dec 2011.

 Dwarf novae are similar to novae in that they involve a binary star system with a white dwarf companion, but the mechanism of energy release is believed to be from collapse rather that detonation of accreting shells of matter.

They are often too dim for me to image, but the dwarf nova imaged above was within my range.