T Draco - Some questions...Double...variable...

[mdstuart]

This looks an interesting object..

Its a double and one star is a variable..but at minimum now..

It is at an xray source point..why?

Its a spectral type NEVAR.....but there is nothing on this on google..what does it mean..

Is it a true double or just optical?

How far away are the stars...

Lots of questions and no answers...

Over to you experts...I want to know more..

Mark

[ronin]

Try:

Carbon star, MIRA variable, and a double.

Google search for "t draconis" turns up a few results.

[Astro Imp]

Just found this:- https://www.flickr.com/photos/latent0image/11529575975/

HTH

[Astro Imp]

Ronin, you're too quick for me, but I get there eventually!!

[ronin]

Alan, I posted then it disappeared, posted a second time with the above and checked and again gone.

Exitted SGL, shut down browser, restarted PC and checked back and 1 entry is present.

Seems to have occurred elsewhere in a post - Meade LPI - first post vanished.

Not sure if I have a problem or what.

Almost looks like post goes unless or until someone else posts after me.

Weird.

[mdstuart]

Thanks for the links peeps...Just found it in my 14 inch..it was too faint for the 5 inch reflector..

Nice grouping as per your picture...quite hard to star hop to it!

The Mira star T is at mag 12 so near minimum I guess...I will enjoy going back to it as it brightens this Autumn..

So what is a NEVAR spectrum, how far away is it and is it a true or optical double?

Mark

[ronin]

From what I read it is a true double.

No idea what a NEVAR spectrum is, did try a search or two but nothing that made sense.

Seem to recall Nevar coming up as a name, suppose that could mean "he" refered to it and attached his name as a shot at fame, and you managed to come across what is possibily the one reference to it.

Being a carbon star search for those, also it seems to have a designation of: GSC 3914: 546

There is a spreadsheet on dvaa.org and the last column may be the distance, but they do not say specifically what it is.

The Astroleague carbon star list has it in but no distance.

https://www.astroleague.org/files/obsclubs/CarbonStar/CarbonStar-List.pdf

Just found an old reference I had.

Spectral type MAY be Ne Var - as in Variable. The ref I have says Spec N0e, the terms may have changed and it is now classed as spectral type Ne Variable (NEVAR). Bit of a long shot.

As the UK appears to have nothing like the observing programs I suspect that answers lie with The Astro League, RASC and AAVSO.

Did expect to locate a distance for it however.

[ronin]

Another designation is CGCS 3921.

Vizier gives spectral type as Ne

http://vizier.u-strasbg.fr/viz-bin/VizieR-S?CGCS%203921

Simbad says Nev

http://simbad.u-strasbg.fr/simbad/sim-id?Ident=GCVS%20T%20Dra

So I suspect spectral type is listed at times as Ne Var.

Simbad also give 25 other designations for t Draco so happy searching through each.

The AAVSO listing is: http://www.aavso.org/vsx/index.php?view=detail.top&revid=85021

Another (bit messy) source is:

http://www1.ynao.ac.cn/~jinhuahe/know_base/catalogues/sourcelists/Sourcelists.htm

About half a mouse wheel turn down if List of C Stars (C=Carbon apparently)

[mdstuart]

Thanks mate...clearly an interesting one if little is known about it..

One to observe and then plot its curve and work out an orbit...we could try parallax!...only joking..

I appreciate your efforts. I will check out the links

I am going to get the folks at the Bristol Astro society on to it on Friday and put it in my talk!

Mark

[ronin]

Fun bit was locating a designation for it other the t Draconis, very few refer to that, the CGCS number was the one that started to give the information.

Looks like Harvard (I think it was them) manage to use spectral type Ne, then add V or Var on to that.

From what I recall there are three carbon stars in Draco, may be others. So seems to have a few.

As you said it is a double, true not visual, and variable - although I gather all carbons are defined as variable in one way or another. Was it a 442 day cycle ??