Epsilon Aurigae.....your help needed!

[david scanlan]

Hi,

In mid 2009 the variable star Epsilon Aurigae will enter its mid eclipse phase and astronomers around the world are turning their scopes onto this star in the hope of learning more about it.

We have known the star is a variable for over a century but astronomers do not know what is eclipsing what and your observations regardless of how many or how little you submit will be of major interest to professional astronomers world wide.

We desperately need observations in the run up to the eclipse, during the eclipse and after the eclipse.

Please help us out by emailing your observations to variablestar@popastro.com

Feel free to post any questions you may have

Regards

Dave

[david scanlan]

Come on guys.....

someone must be interested in helping out

There wont be another eclipse of this star for 20 years :-)

Dave

[Macavity]

Can't really help... as yet. But was rather inspired, way back, by Sir P's remarks in my/his 1963 "Observer's Book" i.e. "... the fainter component of Epsilon is the largest star known to us, with a diameter of 1,800,000,000 miles". Should be a sufficiently large (?20 A.U.) Carrot (sic?), since I imagine this to be ostensible true, to this day...

[AlexG]

Yes, Dave

I am sure we can put it on the to-do list.

We need to look at the popastro website for details, right?

AG

[jgs001]

Dave, I wouldn't know where to start, what to look for or how to report it, although I could find Epsilon Aurigae (at a push )...

[david scanlan]

Thanks Everyone :-)

Most of the info you will need can be found on the SPA VSS site here http://www.popastro.com/sections/vs.htm

Updated charts will hopefully will be online sometime this week but we have problems at the moment with our forum boards so there might be a slight delay

There is piece written about Eps Aur in our Variable vista this month which can be found here http://www.popastro.com/sections/vs/vs-feb2008.htm

This also has a chart for finding the star

Hope this helps and look forward to your feedback and any possible observations

Dave

[jgs001]

Dave, I'll do my best to remember to include an attempt to guesstimate the brightness each time I get out. I've only just started in Astronomy really (3 months ago), so I don't really have much of a clue about star magnitudes at the moment.

[david scanlan]

Thats OK

Its a good area to get into even in passing as knowing, understanding and estimating magnitudes is something that will pass over onto many other astronomical areas including deep sky, comet and meteor observing

Dave

[Kaptain Klevtsov]

Dave, would it be of any use to post images of the area annotated with date and time, location etc? I expect it will be a small thing to snap a frame or two using the goto.

Kaptain Klevtsov

[david scanlan]

That would be fantastic :-)

That way we could actually see the fall in magnitude over the next coming years, for those that miss the eclipse and also would make an excellent record for future generations

Excellent idea :-)

Dave

[jgs001]

Dave, which two stars would you suggest would be a good beginners guide for estimating the Mag against ?

[david scanlan]

Ant of the stars in Gemini are good ones to be honest. Theres some faint ones, 4.2, right through to the brighter ones,1.8.

Heres a comparison star chart for you to use

Hope this helps

Dave

[david scanlan]

Chart has not pasted in so well so if you need the chart in a better format just drop me an email at variablestar@popastro.com

Dave

[jgs001]

Dave, Thanks, printing the chart out now.

[MartinB]

I don't know anything about photometry but I'd be willing to learn. I could get an unsaturated image with the same scope, camera and exposure time, recording FWHM as measured in CCD inspector and record the declination of the image each time and run a comparison against a standard star of known magnitude. Sounds interesting

[david scanlan]

Anything that could help us understand the star a little more will be very worthwhile

Thanks for everyones interest and efforts concerning this :-)

Dave

[Rob]

Hi Dave,

I'll put some effort in with my C8 and report my obs.

Rob

[david scanlan]

Thanks Rob

All help is very much welcomed and I look forward to seeing your observations :-)

Dave

[jgs001]

Dave, I managed to actually see some sky last night. I had a look, estimating Mag is harder than I'd expected. I guesstimated that epsilon was about 3.3 (approx half way between B and C), does this sound about right ? What is the magnitude scale, is it comparable to the db scale, where a shift of 3 db more gives a doubling ? :?

[barkis]

Come on guys.....

someone must be interested in helping out

There wont be another eclipse of this star for 20 years :-)

Dave

Is the period not 27.06 years Dave. Not trying to be a smart a*** here, I have just been reading about this in Burnhams book, and it is an enigma this thing.

Otto Struve in 1962 declared it's history to be "The history of Astrophysics since the beginning of the 20th., century".

And Burnhams goes on to give a very interesting read on this remarkable eclipsing binary. I don't know if the up to date information differs much from what is written in the book. The main suspect, although only conjecture, is that the eclipsing companion is the largest, and coolest star known. I would have thought this puzzle might be solved during the upcoming event, simply because the means by which exo planets are being discovered, could well identify the monster that has been defying detection for all time.

The eclipse phase is in three stages. The deep phase lasts for a year. The partials either side of full, last for six months each. Again I am quoting from Burnhams here Dave.

Ron.

[david scanlan]

Hi

Its commonly thought that eps aur companion is a much smaller star but whats its nature is somewhat of a mystery but it theorised that there is an acrretion disc associated with the two stars.

Although the info in brunhams is good data on variables moves along and progresses at a very rapid scale.

At this stage....we simply dont know but yes your thoughts that the upcoming event might help out with this are very very true and only by observations can we help to understand what exactly is going on :-)

Dave

[david scanlan]

Dave, I managed to actually see some sky last night. I had a look, estimating Mag is harder than I'd expected. I guesstimated that epsilon was about 3.3 (approx half way between B and C), does this sound about right ? What is the magnitude scale, is it comparable to the db scale, where a shift of 3 db more gives a doubling ?

Technically no estimate is too inaccurate :-)

Your estimate of 3.3 is not too far off the mark and since January I have seen observations submitted between 3.1 all the way through to 4.0 so your estimate falls within the expected parameters

Keep up the good work.

Please can you email your observations to me at variablestar@popastro.com in the following format would be fantastic

Your Name

Stars Name

Estmated Mag

Time

Date

That way I have a complete record of who has submiited what observations and you can be given approriate credit.

Many Thanks

Dave

[jgs001]

Dave, Email sent. I just wanted to check if I'd understood and found the correct playing field

[david scanlan]

You did indeed

Many Thanks

I will insure this is logged and recorded as your observation

Dave

[Viking]

A post on cloudynights gives a link to the largest known star. Linking to the given URL runs a simulation starting with our planets then going through a dozen or more stars.

http://www.techdo.com/images/largest-know-star.htm

John