sigma Orion - an enigma ?! - (solved in October,29)

[jsmoraes (Jorge)]

My last capture shows Sigma Orion star. Wikpedia says it is a system of five stars. But I saw seven stars, despite of bad focus. Searching in Aladin Sky Map it seems to be 3 stars together Sigma, and 2 stars together D or E, really I don't know which of them. Therefore it should be 7 stars. Searching in Sky-Map I only saw 2 stars in Sigma's region and I saw 2 stars together D or E, too.

My question: Sigma Orion is a 5, 6 or 7 stars system ?

[Larryp (Laurie)]

Good capture, Jorge!

[billdan (Bill)]

Looks like 7 to me
Bill

[mithrandir (Andrew)]

Jorge,

Vizier says there are 5 stars within 1 arcmin of the coords of Sigma Ori (see I/274/ccdm) - CCDM 05387-0236 A/B/C/D/E.

CCDM 05386-0234 A/B/C/D are the group at about PA 45.

The Aladin image agrees with your photo.

[jsmoraes (Jorge)]

Would be 5 stars with gravitational interaction and the others 2 stars don't belong the system, being only visual appearence ?

One seems to be very close Sigma Star! And the other seems to be side by side !

[jsmoraes (Jorge)]

I know is out of topic, and ok to me if it has to be tranfered to another place of forum, but ...

And, now, worse to me !

Sigma Orionis seems to be a cluster, with numerous low mass stars, brown dwarf, with mass only a few times that Jupiter.

http://stars.astro.illinois.edu/sow/sigmaori.html

Or

Herschel describes as two groups of 3 stars. Barlow, as two groups of 4 stars, adding two little stars to each group of Herschel.

Main stars:

component A, mag 4 with a a little mag 11 star

component B, mag 8

Note: It seems my photo shows these 3 stars.

component C, mag 7

component D, mag 8,5 with a little mag 12 ( more distant from A)

Note: My photo shows two stars with same magnitude, side by side, and near other star (what are their names ?).

component E, mag 9

http://www.cosmovisions.com/ori.htm

[mithrandir (Andrew)]

Originally Posted by jsmoraes

Note: My photo shows two stars with same magnitude, side by side, and near other star (what are their names ?).

Jorge, since you haven't marked which stars you mean does this help with identification? I have a version using the Tycho2 catalog but GSC2 puts labels on many more objects.

[jsmoraes (Jorge)]

Thanks Laurie, Bill and Andrew. I was thinking about stars D and E.

S1MH000460 should be A an B and little star mag 11. To me it seems there are 3 stars in my photo.

S1NG000452 should be C.

And who is D and E ? S1MH000425 (two stars) and S1MH000415 ?

Or D should be S1MH000384 (star at top of image) ? Perhaps S1MH000350 ?

Many texts tell about 5 stars (A,B,C,D and E) but none shows who is who.
The reference most distant is relative. And the description of distance with arcseg wasn't clear to me.

[jsmoraes (Jorge)]

Ok , I did a great confusion! With my GSO 305 mm and Canon 350 D the resolution don't permit the separation A and B. So, the system is too more together then I thought to be.

I received a photo with correct identification.

Ufa ! At least, there isn't nothing wrong in the sky. But, with me ... Attention, Jorge! Wake up, man !