M82, a strange structure
Posted 26 March 2010 - 12:47 PM
M82 has some dark lane and bright area.
And I observed strange structure in North-Western edge.
Very faint nebulosity is there.. It remind me melope's shape
(looks like sweep with a broom!)
But any photography of M82 doesn't have such structure.
I don't know it is true or false.
Have you ever seen this structure before?
Below is M82's photo. (google search)
Date : 2010.3.13
Time : 8:10~9:30 (UT)
Location : Cheonmunin-maul, Kangwon-do, S.Korea
Seeing : 5/5
Limiting Mag. : 5.0 → 4.5
Temp : -4C
Equipment : Discovery 15inch dobsonian
Pentax XL 14mm (136x)
White conte & pastel, black paper
Posted 26 March 2010 - 04:20 PM
Posted 26 March 2010 - 05:13 PM
FYI, infrared photos do show material being ejected into the region you show though - link
Posted 26 March 2010 - 11:22 PM
Could it be an optical illusion though? I noticed on some DSS photos that while the bright part of the galaxy narrows and bends "up" on the side with your fan, the galaxy's general shape remains straight. Thus would it be possible for the eye to perceive the bright part as a sort of straight 'guide line', and thus extrapolate that the actually unbent part of the galaxy fans out in the direction opposite the bending.
Add in relatively minor glare from that bright star, and it could, I think, be enough to make it look as if there's an extension there.
Posted 27 March 2010 - 12:22 AM
Excellent sketch of M82, and terrific analysis. Here are some images M82 Chandra , taken with the Chandra telescope. They show the outflow of material from the galaxy in above and below the central region but I don't see a flow out from where the broom you observed is. Hrundi offers some good possible alternatives.
Posted 27 March 2010 - 02:41 PM
Posted 27 March 2010 - 04:23 PM
I found one sketch out of 41 in Deepskylog (click link here) who may have the same mistery triangle. The sketch was done by Guido Gubbels with a 25 cm dobson @ x178.
Link to image
EDIT: Sorry Jef - you must have explicit permission to repost someone else's work. A link is permissible however. Also, I trimmed down your link text and made it clickable so folks could get to the website easier. CH
Posted 27 March 2010 - 08:22 PM
As for the fan like nebulosity you've captured, it may be an optical illusion. I find that when observing many dim, diffuse objects the hazy nebulosity (or galaxy glow) nearer stars can seem to be a little brighter. Just a guess.
Posted 28 March 2010 - 11:01 AM
Posted 28 March 2010 - 12:39 PM
I'm also confused about illusion or real structure....
So, I'll observe M82 next time with my experienced colleagues.
Posted 28 March 2010 - 02:17 PM
My impression is that the 'bright' star contained within the nebulous extension is the culprit. The light from this star could be scattered by one or more of the following:
- dirty optics.
- smudge on the eyepiece.
- dew on the optics.
- thin cloud.
- your own eye.
And the proximity of the galaxy and the star is a quite good candidate for the appearance of spurious extensions such as this. The visual system has a powerful propensity for making such 'connections.'
Posted 28 March 2010 - 03:17 PM
Posted 28 March 2010 - 04:51 PM
There actually is a fan shaped extension in that direction that is visible in the hubble picture. I'd think it would be invisible the the human eye though. You probably saw the contrast between the dark lane and the glowing sky around it, along with the light from the nearby star, and assumed it to be a larger structure.
You can't always count on your brain accurately representing what your eyes are seeing. I always "see" the complete bridge between M51 and NGC 5195, but I almost never actually see it.