APOD: Reflections on the 1970s (2023 Feb 02)

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APOD: Reflections on the 1970s (2023 Feb 02)

Post by APOD Robot » Thu Feb 02, 2023 5:05 am

Image Reflections on the 1970s

Explanation: The 1970s are sometimes ignored by astronomers, like this beautiful grouping of reflection nebulae in Orion - NGC 1977, NGC 1975, and NGC 1973 - usually overlooked in favor of the substantial glow from the nearby stellar nursery better known as the Orion Nebula. Found along Orion's sword just north of the bright Orion Nebula complex, these reflection nebulae are also associated with Orion's giant molecular cloud about 1,500 light-years away, but are dominated by the characteristic blue color of interstellar dust reflecting light from hot young stars. In this sharp color image a portion of the Orion Nebula appears along the bottom border with the cluster of reflection nebulae at picture center. NGC 1977 stretches across the field just below center, separated from NGC 1973 (above right) and NGC 1975 (above left) by dark regions laced with faint red emission from hydrogen atoms. Taken together, the dark regions suggest the region's popular moniker, the Running Man Nebula. At the estimated distance of Orion's dusty molecular cloud this running man would be about 15 light-years across.

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Ann
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Re: APOD: Reflections on the 1970s (2023 Feb 02)

Post by Ann » Thu Feb 02, 2023 6:59 am

Today's APOD is fine, but in order to make sense of the 1970s we'll have to look at the full size version of the APOD:

APOD 2 February 2023 detail annotated.png

As for where NGC 1977 is, I'll just take APOD Robot's words for it that it is below the Running Man! :D

NGC 1973 is illuminated by HD 36958, a star of spectral class B3/B5 (according to Simbad). A star of these spectral classes produces a lot of blue light, but not enough UV light to ionize a red emission nebula, so it is perfect for lighting up a blue reflection nebula.

NGC 1975 is illuminated by by at least three stars, the brightest of which is HD 294262. Simbad calls its spectral class A E, which is very helpful. Not. Well, in spite of that confusing "A E", I'd say that this is also a B-type star, although cooler than the one lighting up NGC 1973. I'm sure you're all taking notes! 😄


Let's look at the star that is the most important player here:


42 Orionis in the Running Man Nebula Adam Block.png
42 Orionis in the Running Man Nebula.
Image credit: Ngc 1535 of English Wikipedia.


42 Orionis is a star of spectral class B1V, which means it is just barely hot enough to ionize a faint red emission nebula. It also emits copious blue light to paint the surrounding "sky" blue. But the Running Man can thank the wheezing UV light of 42 Ori for the dull red color of his (admittedly somewhat loose) spandex suit.

Finally, yes, let's grab this moment to think a bit more about the 1970s, shall we? :D


Pictures of the 1970s.png
Click to play embedded YouTube video.


Mary Hopkin actually recorded the song in the video in 1968. That's close enough to the 1970s.

Ann
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Re: APOD: Reflections on the 1970s (2023 Feb 02)

Post by AVAO » Thu Feb 02, 2023 11:19 am

APOD Robot wrote: Thu Feb 02, 2023 5:05 am Image Reflections on the 1970s
Image
APOD 2015 December 29 Image Credit & Copyright: Raul Villaverde Fraile

I like the dusty Orion Nebula especially in the Infrared! :roll:

Image

https://www.herschel.caltech.edu/image/nhsc2022-002a
https://www.herschel.caltech.edu/system ... 1669229196

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Re: APOD: Reflections on the 1970s (2023 Feb 02)

Post by orin stepanek » Thu Feb 02, 2023 1:51 pm

NGC1975RunningMan_1024.jpg
I had no problem finding the running man; but i can't count 3 nebulae! :oops:
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Re: APOD: Reflections on the 1970s (2023 Feb 02)

Post by Holger Nielsen » Thu Feb 02, 2023 2:38 pm

Ann writes:
I'm sure you're all taking notes!
Indeed, I always enjoy reading your mini-lectures with their attention to interesting details!

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Re: APOD: Reflections on the 1970s (2023 Feb 02)

Post by De58te » Thu Feb 02, 2023 2:55 pm

Speaking of astronomers ignoring the 1970s, I'd be more interested to see where NGC 1976 is? It is the year I graduated from high school, and it was also a bicentennial year in the USA. What is the reason that 1975 and 1977 got a reflection nebulae but why was 1976 ignored?

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Re: APOD: Reflections on the 1970s (2023 Feb 02)

Post by DonB312 » Thu Feb 02, 2023 4:37 pm

De58te wrote: Thu Feb 02, 2023 2:55 pm Speaking of astronomers ignoring the 1970s, I'd be more interested to see where NGC 1976 is? It is the year I graduated from high school, and it was also a bicentennial year in the USA. What is the reason that 1975 and 1977 got a reflection nebulae but why was 1976 ignored?
NGC 1976 is the Orion Nebula.
Don

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Re: APOD: Reflections on the 1970s (2023 Feb 02)

Post by AVAO » Thu Feb 02, 2023 8:48 pm

orin stepanek wrote: Thu Feb 02, 2023 1:51 pm
Image
I had no problem finding the running man; but i can't count 3 nebulae! :oops:
...I was wondering the same...

Image
https://de.wikipedia.org/wiki/NGC_1977