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Herbig-Haro 1 and 2 variability

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#1 Akarsh Simha

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Posted 27 February 2024 - 02:49 AM

At a recent (January new moon) BAS star party in south India, I happened to look at the NGC 1999 and HH1 / HH2 field in Orion through a 16" dob.

 

(2024-01-11) After carefully studying the field, I could hold HH2 about 70% of the time. It seemed slightly shifted west from the location seen on the POSSII. I was unable to detect HH 1, and I did not push very hard as it was a shared telescope.

 

Coming back to my notes, I see that I have two previous log entries for these objects. At Okie-Tex Star Party in 2021 October, I had somewhat similar results.

 

(2021-10-06) I seeing HH2 about 50% with averted vision. HH1 was way fainter, a threshold object which yielded ~4 flashes.

 

But previously in 2016 from Ft. Griffin in Texas, I had the opposite result:

 

(2016-01-10) I logged HH2 as more stellar and more faint, held about 10% of the time with averted vision. Of HH1, I wrote, "Diffuse, irregular and brighter. Held nearly 50% of the time, appeared much bigger [than HH2], seemed irregular and somewhat elongated in shape, axis of elongation roughly E-W.

 

I notice that in 2020, Scott Harrington reports HH2 as being brighter. (https://www.cloudyni...g-haro-objects/)

Uwe Glahn's observation sometime in 2006 reports HH2 brighter again.

 

I compared my 2016 sketch with the POSSII image, and the sketch checks out...

HH1_HH2.jpg

HH1_HH2_sketch.jpg

 

Now this is not absurd per se because Herbig-Haro objects can show variability in position, shape and brightness over the course of days or weeks. But I'm wondering if anyone else has noticed such substantial variation in the relative brightness of HH1 and HH2.

 

Clear Skies

Akarsh

 


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#2 Keith Rivich

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Posted 27 February 2024 - 06:55 PM

At a recent (January new moon) BAS star party in south India, I happened to look at the NGC 1999 and HH1 / HH2 field in Orion through a 16" dob.

 

(2024-01-11) After carefully studying the field, I could hold HH2 about 70% of the time. It seemed slightly shifted west from the location seen on the POSSII. I was unable to detect HH 1, and I did not push very hard as it was a shared telescope.

 

Coming back to my notes, I see that I have two previous log entries for these objects. At Okie-Tex Star Party in 2021 October, I had somewhat similar results.

 

(2021-10-06) I seeing HH2 about 50% with averted vision. HH1 was way fainter, a threshold object which yielded ~4 flashes.

 

But previously in 2016 from Ft. Griffin in Texas, I had the opposite result:

 

(2016-01-10) I logged HH2 as more stellar and more faint, held about 10% of the time with averted vision. Of HH1, I wrote, "Diffuse, irregular and brighter. Held nearly 50% of the time, appeared much bigger [than HH2], seemed irregular and somewhat elongated in shape, axis of elongation roughly E-W.

 

I notice that in 2020, Scott Harrington reports HH2 as being brighter. (https://www.cloudyni...g-haro-objects/)

Uwe Glahn's observation sometime in 2006 reports HH2 brighter again.

 

I compared my 2016 sketch with the POSSII image, and the sketch checks out...

attachicon.gif HH1_HH2.jpg

attachicon.gif HH1_HH2_sketch.jpg

 

Now this is not absurd per se because Herbig-Haro objects can show variability in position, shape and brightness over the course of days or weeks. But I'm wondering if anyone else has noticed such substantial variation in the relative brightness of HH1 and HH2.

 

Clear Skies

Akarsh

They are now on my list to monitor!


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#3 sgottlieb

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Posted 01 March 2024 - 03:43 PM

In his February 2022 Sky & Tel article on NGC 1999, Howard Banich wrote a sidebar on our joint observation back in 2012 of HH1 and HH2 from Mauna Kea VIS along with an astronomer from the NASA Infrared Telescope Facility (IRTF).


The first time I saw HH 1/2 was in January 2012 at the Visitor Center on Mauna Kea. After the nightly sky show had ended, several local observers were sharing views through their telescopes, one of which was an intriguing 20-inch ball scope. Mike Connelley was operating the scope, which he had made himself. A small group had coalesced around Mike, including myself and Steve Gottlieb, who suggested we look at HH 1/2.

It turned out that Mike is not only a talented amateur telescope maker and observer, but a professional astronomer based on the Big Island of Hawai‘i. When Steve suggested looking for HH 1/2, our gracious host said something to the effect of “you mean we can actually see them in my scope?! I’m researching HH objects right now!”

 

Steve replied “Sure!” and asked if he could move the scope to the proper position, and soon everyone in our small group had a look. Mike was thrilled to actually see the objects he knew so well through his research. We were all thrilled, too, both for him and because these are subtle objects most of us hadn’t seen before.

 

As it turns out, a 2013 paper about HH 222 and V380 Orionis is one of the primary sources for this article, and I only realized Mike is a co-author just before my deadline. Even better, all three of us have similar memories of this long-ago encounter in the dark, confirming that sometimes the world really is a small place.

 

I've also looked at the pair with my old 17.5" a couple of times, as well as with my 18".  HH 1 was very difficult in both scopes and was barely seen as a nearly stellar spot.  It wasn't difficult in Jimi Lowrey's 48" (in 2011), but I still logged it as "very faint, extremely small, possibly elongated, 4"x2" NW-SE".

 

In all cases (including Mauna Kea), I found HH 2 noticeably easier: "at 280x-380x Herbig-Haro 2 appeared very faint, very small, ~5" diameter.  Once identified I was surprised it was not difficult to view with concentration and averted vision."


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#4 Akarsh Simha

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Posted 06 March 2024 - 02:58 AM

Thanks for sharing your observations and the fascinating anecdote from Howard's article, Steve. Adds to the data.



#5 Alex Swartzinski

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Posted 06 March 2024 - 10:45 AM

Great observations Akarsh!

 

Seeing DSOs change between observations is very cool. 

 

I tried for both of these objects last Saturday night. HH1 and HH2 were suspected, but I wasn't confident enough in the observations to confirm them. 

 

How much magnification are people using on these objects? I don't recall trying magnification's over 250x. I'm not sure why I didn't try higher powers! 

 

NGC 1999 looked great though!



#6 Bill Weir

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Posted 06 March 2024 - 12:24 PM

 

How much magnification are people using on these objects? I don't recall trying magnification's over 250x. I'm not sure why I didn't try higher powers! 

 

This is my answer. Observing HH 1 & 2 was part of my working on the RASC Deep Sky Challenge list. This observation was from back in Feb. 2008. Looking back at my notes I see that it was at 365X I could hold them about 50% of the time and that it wasn’t until 456X that I could really hold them all of the time. They were stellar with HH 2 seeming slightly “fatter”. 

 

Seeing at this observatory site is often very good and back then the transparency in the winter was often excellent. Seeing still as good, transparency not so much. Oh and as I keep saying I wish Port Angeles across the strait would stop adding lights.

 

Bill

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#7 Akarsh Simha

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Posted 07 March 2024 - 02:03 AM

Thanks for your report, Bill. The RASC deep-sky challenge list is really one of the best lists ever put together in my opinion, and I too completed it late last year.

 

I sometimes forget to note the exit pupil / magnification in my logs even though it's such an important parameter. Tells me I should try to up the power next time I try (which might be tomorrow).

 

Clear Skies

Akarsh




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