Star cluster in M66?

[Ivan Maly]

Last night I was observing M66 from Cherry Springs (21.80 mpsas by SQM-L) with my 16" and noticed a starlike object superimposed on the prominent star cloud just off the NW end of the bar. It was seen best at 300x with ZAOII-6, although I had to wait for moments of stabilization, because seeing was generally bad. I recorded it on the sketch and looking at some amateur photos I had with me began to suspect that it might not be a superimposed star, but could not be certain because of their resolution. In the ESO image of M66 on Wikipedia there is a clear candidate and it does not look stellar or superimposed. What do you think? Have you seen it? Is this a Milky Way star? Is this a known object in M66? I could not find anything on it in the literature or databases, but maybe I just don't know how to look.

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Left, sketch. Right, ESO Wikipedia. The frame of the photo is indicated on the sketch. North up, west right in both (approximately).

[Clear Skies]

If it's known, it's likely to be in NED. It's not in NED.

The second image you posted is mirrored horizontally?
Assuming I have the correct position @ 11:20:14.5 +13d00m45s
15' DSS: http://archive.stsci.edu/cgi-bin/dss_search?v=poss2ukstu_blue&r=11+20+14.50&d=%2B13+00+45&e=J2000&h=15&w=15&f=gif&c=none&fov=NONE&v3=
1' DSS: http://archive.stsci.edu/cgi-bin/dss_search?v=poss2ukstu_blue&r=11+20+14.50&d=%2B13+00+45&e=J2000&h=1&w=1&f=gif&c=none&fov=NONE&v3=

the best NED comes up with within a 2 arcminute radius is a radio source. Nothing stellar, nebulous or superimposed:
http://ned.ipac.caltech.edu/cgi-bin/objsearch?search_type=Near+Position+Search&in_csys=Equatorial&in_equinox=J2000.0&lon=11%3A20%3A14.5&lat=13d00m45s&radius=2.0&hconst=73&omegam=0.27&omegav=0.73&corr_z=1&z_constraint=Unconstrained&z_value1=&z_value2=&z_unit=z&ot_include=ANY&nmp_op=ANY&out_csys=Equatorial&out_equinox=J2000.0&obj_sort=Distance+to+search+center&of=pre_text&zv_breaker=30000.0&list_limit=5&img_stamp=YES

Nothin in SIMBAD either..!

Cheers,


Victor

[Ivan Maly]

No, the photo is not mirror-reversed. My estimate for the position of the object I indicated is 11h20m14s, +13deg 00' 20". The area looks overexposed on the DSS GIF. You picked instead the second brightest almost starlike knot in this star cloud, to the E, in a less busy area.

I edited the OP to indicate the area covered by the photo on the sketch.

[Dragan]

Hi Ivan,

Best I can tell, according to your coordinates, is that it is SN1989B (http://ned.ipac.caltech.edu/cgi-bin/objsearch?objname=SN1989B&extend=no&out_csys=Equatorial&out_equinox=J2000.0&obj_sort=RA+or+Longitude&of=pre_text&zv_breaker=30000.0&list_limit=5&img_stamp=YES). Now, are you seeing a SN from 20 years ago? I doubt it.

I've tried all the usual resources and was unable to find anything, stellar or non, that corresponds with what you're seeing. Now you've got me curious. My guess that its something in M66 you're seeing. I just can't find what it is.

Can you pinpoint what you're seeing on a high res image?

[Ivan Maly]

Dragan, yes, the SN of 1989 was very close to that location. It is not surprising because generally the star cloud off the NW end of the bar seems to be the most active area of star formation.

In the ESO image in my post, the brightest compact knot is indicated by the black arrow. It is as close to the location I recorded as it can possibly be given the precision of locating something visually. The only alternative is the even more starlike object just to its S (N is up in my attachments). But looking at this photo I doubt the southern object would be as prominent visually as the northern (indicated) one. This ESO image from the Wikipedia entry on M66 is the highest-resolution photo I could find.

I am looking at some new papers now that seem relevant...

[Ivan Maly]

Found the identification in the 1974 AJ paper by Paul Hodge (http://adsabs.harvard.edu/full/1974ApJS...27..113H). It is his HII region #44. (The more starlike and fainter object in the ESO photo in my original post just to the S is also an HII region described by Hodge, but it is fairly obvious that it was not what I saw. I just wanted to exclude the possibility that it was a Milky Way star that could be unresolved visually from the bright object.) This - what I will call Hodge 44 in M66 - is, I believe, the most distant HII region I have seen.

[Ivan Maly]

It is probably this object (Hodge 44) that was seen by our Steve Gottlieb with 48": "very faint star or knot was seen at the very north tip of the bar" (http://www.astronomy-mall.com/Adventures.In.Deep.Space/NGC%203001%20thru%20NGC%204000.html).

I now realize that the few glimpses I had of another star to the NE in the same star cloud were of the Hodge HII region 32, the second most prominent knot in the ESO image, ENE of the one indicated and photographically on the very edge of the star cloud. It is not included on the sketch. Either I did not feel certain enough of that observation or, more likely, I just forgot to add that "star" as I was sketching at 3 in the morning after several hours of observation.

568

[isaacnewtonzhang]

cool!the adventage of big dobson,maybe i am witnessing a new discoverry?