APOD: Rigil Kentaurus and Sandqvist 169 (2019 Apr 13)

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APOD: Rigil Kentaurus and Sandqvist 169 (2019 Apr 13)

Post by APOD Robot » Sat Apr 13, 2019 4:09 am

[img]https://apod.nasa.gov/apod/calendar/S_190413.jpg[/img] Rigil Kentaurus and Sandqvist 169

Explanation: Rigil Kentaurus is the bright star near the top of this broad southern skyscape. Of course it's probably better known as Alpha Centauri, nearest star system to the Sun. Below it sprawls a dark nebula complex. The obscuring interstellar dust clouds include Sandqvist catalog clouds 169 and 172 in silhouette against the rich starfields along the southern Milky Way. Rigil Kent is a mere 4.37 light-years away, but the dusty dark nebulae lie at the edge of the starforming Circinus-West molecular cloud about 2,500 light-years distant. The wide-field of view spans over 12 degrees (24 full moons) across southern skies.

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Ann
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Re: APOD: Rigil Kentaurus and Sandqvist 169 (2019 Apr 13)

Post by Ann » Sat Apr 13, 2019 6:24 am

Really nice picture. Beautifully detailed and richly resolved. Beautiful colors.

Is the prominent bluish star at 4 o'clock Alpha Circini? And is the prominent bluish star near the bottom right corner Beta Triangulum Australis? Is the bluish double star to the upper left of Sandqvist 169 Delta Circini and friend?

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Re: APOD: Rigil Kentaurus and Sandqvist 169 (2019 Apr 13)

Post by De58te » Sat Apr 13, 2019 6:42 am

This is interesting. If it wasn't for the 'us' the names Kentaurus and Centauri almost rhymes. It would even be closer if you pronounced the C as a hard C like in the words cat, candle or Canada. I've always pronounced Centauri with a soft C as in cent, city, or celebrity. Which makes me wonder, how is Centauri officially pronounced? Hard C or soft C?

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Re: APOD: Rigil Kentaurus and Sandqvist 169 (2019 Apr 13)

Post by Nitpicker » Sat Apr 13, 2019 7:08 am

De58te wrote:
Sat Apr 13, 2019 6:42 am
This is interesting. If it wasn't for the 'us' the names Kentaurus and Centauri almost rhymes. It would even be closer if you pronounced the C as a hard C like in the words cat, candle or Canada. I've always pronounced Centauri with a soft C as in cent, city, or celebrity. Which makes me wonder, how is Centauri officially pronounced? Hard C or soft C?
Both names stem from the mythical centaur. It is likely spoken with a hard k sound in Greek and a hard q sound in Arabic, but with a soft c in Latin and English.

Amazingly deep APOD.

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Re: APOD: Rigil Kentaurus and Sandqvist 169 (2019 Apr 13)

Post by rcolombari » Sat Apr 13, 2019 10:51 am

Thanks for featuring my image as APOD!

I think I figured out where Proxima Centauri is in the field: Am I right??

Best regards

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Re: APOD: Rigil Kentaurus and Sandqvist 169 (2019 Apr 13)

Post by neufer » Sat Apr 13, 2019 11:27 am

https://en.wikipedia.org/wiki/Where%27s_Wally%3F_(book) wrote: <<Where's Wally?, published in the United States and Canada as Where's Waldo?, is the title of the first book in the Where's Wally? series, published in 1987. In the book, Wally travels to everyday places, where he sends postcards to the reader (which are the pictures in the book), and the reader must locate Wally in the postcard. The book became an instant best-seller. Where's Wally? was re-released in October 1997 in a special 10th anniversary edition form. The location of Wally was changed in each picture and additional characters were added for the reader to find (Woof, Wizard Whitebeard, Wenda, Odlaw, the Wally Watchers, and others).

The Wally series is quite evocative of an earlier children's book titled Where's Wallace? (by Hilary Knight), in which a red-headed orangutan escapes from the zoo and "hides" in highly detailed picture panoramas, including beach, department store, circus, stadium, and museum.

The book has been challenged in libraries and schools because of a topless woman near the upper right of the "On the Beach" scene. It ranks #87 on the American Library Association's "100 Most Frequently Challenged Books" list (1990-1999) because of the exposed breast. The woman is wearing a bikini top in the 1997 special edition release. A similar happening occurs in "The Campsite" where children open a tent on a man while he is undressing. In the original, although his genitals are blocked from view by his hand, he is clearly naked. In the 1997 special release, however, he is wearing white briefs.>>
rcolombari wrote:
Sat Apr 13, 2019 10:51 am
Thanks for featuring my image as APOD!

I think I figured out where Proxima Centauri is in the field:

Am I right??

Best regards
Art Neuendorffer

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Ann
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Re: APOD: Rigil Kentaurus and Sandqvist 169 (2019 Apr 13)

Post by Ann » Sat Apr 13, 2019 11:29 am

rcolombari wrote:
Sat Apr 13, 2019 10:51 am
Thanks for featuring my image as APOD!

I think I figured out where Proxima Centauri is in the field: Am I right??

Best regards
Proxima Centauri is terribly hard to find. :(

I googled "Proxima Centauri", and these were the two best wide-angle pictures I could find:

https://upload.wikimedia.org/wikipedia/ ... ntauri.jpg (685 KB)

https://epod.usra.edu/.a/6a0105371bb32c ... 730970b-pi (4.27 MB, an EPOD image)

I think I can see a line of 10th and 11th magnitude stars relatively close to Proxima Centauri in the pictures I posted, anchored by 8th magnitude star HD 126793. I'm not sure I can see that line of stars in your closeup. Maybe possibly maybe the star that you have pointed out as Proxima Centauri could in fact be HD 126793.

OH, wait!!! I think I can see that line of stars in your closeup!!

Yes, I think you may have found Proxima!!! :D :clap:

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Re: APOD: Rigil Kentaurus and Sandqvist 169 (2019 Apr 13)

Post by orin stepanek » Sat Apr 13, 2019 2:15 pm

Wow! The dust clouds are dark; but sprinkled with a lot of small stars; so many in fact that the clouds look similar to sandpaper! 8-) :?
Orin

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Re: APOD: Rigil Kentaurus and Sandqvist 169 (2019 Apr 13)

Post by NGC3314 » Sat Apr 13, 2019 6:26 pm

rcolombari wrote:
Sat Apr 13, 2019 10:51 am
Thanks for featuring my image as APOD!

I think I figured out where Proxima Centauri is in the field: Am I right??
I agree on the ID. Here is a 2014 image I did with a remote telescope (field about 10 arcminutes), where the ID was confirmed by the motion year-to-year (and huge change since the digitized Sky Survey photographs). Comparison shows its proper motion from 2014 to your image, as well. It sure looks like a long way from Alpha.
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Ann
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Re: APOD: Rigil Kentaurus and Sandqvist 169 (2019 Apr 13)

Post by Ann » Sat Apr 13, 2019 7:34 pm

NGC3314 wrote:
Sat Apr 13, 2019 6:26 pm
rcolombari wrote:
Sat Apr 13, 2019 10:51 am
Thanks for featuring my image as APOD!

I think I figured out where Proxima Centauri is in the field: Am I right??
I agree on the ID. Here is a 2014 image I did with a remote telescope (field about 10 arcminutes), where the ID was confirmed by the motion year-to-year (and huge change since the digitized Sky Survey photographs). Comparison shows its proper motion from 2014 to your image, as well. It sure looks like a long way from Alpha.
Alpha, Beta and Proxima Centauri.
Earthsky/ESO.
It is a long way from Alpha indeed!
Jim Kaler wrote:
Alpha Centauri has yet another member, a faint eleventh magnitude (11.05) companion called "Proxima" that is a huge 1.85 degrees (at least 8500 AU) away from Alpha proper and that orbits with a period of at least a three-quarters of a million years. If indeed it does orbit (and that is not certain), it is now on the near side of its path and some 6,000 astronomical units closer than the bright pair, making it actually the closest known star (but since it is part of Alpha, surely it is still fair to call Alpha the closest star).
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Re: APOD: Rigil Kentaurus and Sandqvist 169 (2019 Apr 13)

Post by starsurfer » Sat Apr 13, 2019 8:15 pm

Nice image of an obscure region. There is a lot in Circinus for astrophotographers. An interesting coincidence is the Atacama Photographic Observatory team released a closeup of Sandqvist 172 a few days ago. They also have a closeup of Sandqvist 169, which is also known as the Circinus Cloud.

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Re: APOD: Rigil Kentaurus and Sandqvist 169 (2019 Apr 13)

Post by alter-ego » Sun Apr 14, 2019 1:20 am

Stellarium nicely confirms Proxima's location. Interestingly, the APOD shows Proxima to be about a 30 arcsec westward of Stellarium position. This is consistent with about 9 years of proper motion. I'm using about a 3-yr old version of Stellarium and I don't know how old Proxima's coordinates are. Still, it's likely the obvious position change is, in good part, due to proper motion.
 
Click to view full size image 1 or image 2
Edit: The viewed position difference is purely a prediction error.
I've not used Stellarium for measurably fast-moving stars before. The program does attempt to update Proxima's position based on the "year of last satisfactory observation" which is listed as 2000. It's unclear if/when they'll implement GAIA data.
A pessimist is nothing more than an experienced optimist