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Thread: HII regions in M81

  1. #1
    Member Ivan Maly's Avatar
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    HII regions in M81

    In the spirit of some recent material here, a deeper dive into one of the most observed objects. Last night I was able to hunt down a few of the small HII regions in M81, from the 1983 Hodge-Kennicutt catalog. 20", 250x, SQM 21.6. It's a bit hard to match HK's coordinates to the broadband image. Most identifications are from the Stoyan Atlas of the Messier Objects and two more (305 and 435) are my best attempt using Aladin. Most of these presented a nonstellar or "unstellar" appearance, and the putative foreground star on the N edge of region 746 was also seen, as was the extended object immediately WNW of 652. I'd be interested to hear about other observations of these, and about a method of identification that others use for such objects.

    Last edited by Ivan Maly; January 10th, 2018 at 08:20 PM.

  2. #2
    Member Howard B's Avatar
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    Hi Ivan,

    I used Aladin to identify HII regions in M81, and the regions I've seen are shown here: http://www.skyandtelescope.com/wp-co...82-Details.pdf
    Howard
    28 inch f/4 alt-az Newtonian

  3. #3
    Member Ivan Maly's Avatar
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    Thanks, that's a great approach. I remember your observations now. Incidentally, I saw your region G last night but thought it was a star. Will get back to it.

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    Hi Ivan,

    Incidentally I was writing an article about Holmberg IX so the HII regions weren't too far from that.

    I use NASA's NED for HII regions, or SIMBAD, as well as the ADS to get to the professional articles about them.

    I have recorded 7 HII regions (or groups of HII regions)/stellar associations with my 17.5" at 271x.

    In the hook of the northern arm : (PSK 139), (PSK 170 + PSK 178 + PSK 177) and (PSK 97 + PSK 72)
    In the prolongation of this arm, west of the main core and going south : (PSK 15 + [l92b] 6), ([ZH91] M 81 394 + PSK 17 + PSK 16 + PSK 26) and (PSK 29 +
    HK NGC 3031 741 + PSK 30)
    In the south arm going E and reaching north, around a mag.14 star, the HII regions are not separated but they enhance the arm locally : PSK 414 + PSK 416 +PSK 417 + [l92b] 153 + 155 + 156

    clear skies,
    Yann

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