APOD: Stars and Dust Across Corona Australis (2012 Sep 27)

Comments and questions about the APOD on the main view screen.
User avatar
APOD Robot
Otto Posterman
Posts: 4683
Joined: Fri Dec 04, 2009 3:27 am

APOD: Stars and Dust Across Corona Australis (2012 Sep 27)

Post by APOD Robot » Thu Sep 27, 2012 4:12 am

Image Stars and Dust Across Corona Australis

Explanation: Cosmic dust clouds sprawl across a rich field of stars in this sweeping telescopic vista near the northern boundary of Corona Australis, the Southern Crown. Probably less than 500 light-years away and effectively blocking light from more distant, background stars in the Milky Way, the densest part of the dust cloud is about 8 light-years long. At its tip (upper right) is a group of lovely reflection nebulae cataloged as NGC 6726, 6727, 6729, and IC 4812. A characteristic blue color is produced as light from hot stars is reflected by the cosmic dust. The smaller yellowish nebula (NGC 6729) surrounds young variable star R Coronae Australis. Magnificent globular star cluster NGC 6723 is toward the upper right corner of the view. While NGC 6723 appears to be part of the group, it actually lies nearly 30,000 light-years away, far beyond the Corona Australis dust clouds.

<< Previous APOD This Day in APOD Next APOD >>
[/b]

User avatar
Ann
4725 Å
Posts: 12076
Joined: Sat May 29, 2010 5:33 am

Re: APOD: Stars and Dust Across Corona Australis (2012 Sep 2

Post by Ann » Thu Sep 27, 2012 5:12 am

Oh, this is a wonderful APOD! Really and truly! And Marco Lorenzi is one of the great astrophotographers who regularly grace the Recent Submissions thread in the Astrophotography forum here. Congratulations, Marco! :D :D :D

Note, in the picture, that interstellar dust is typically reddish-brown in color, because it scatters away blue light and preferentially lets through long-wave yellow and red light. But when the dust scatters light in our direction, that light can be very blue. Particularly if it emanates from blue stars, of course!

Note the whitish color of the ancient globular at upper right. (What a skyscape, by the way, with ongoing star formation in the foreground and a circa 10-12 billion-year-old globular in the background. Its whitish color is testimony to the "metal-poor" gas that the stars in the globular are made of. Elements heavier than hydrogen and helium are "cooked up" inside stars, and these elements become part of the "interstellar medium" when the stars that made them die and return much of the gas they were made of to the space around them, either by exploding as supernovae or by ejecting their "outer shells" in planetary nebulae. The older the universe gets, the more generations of stars will have come and gone, the more stars will have returned their metal-enriched innards to space, and the more metal-rich the gas inside galaxies will become. But the globular in this picture was born when the ambient gas was metal-poor. Metal-poor gas gives rise to bluer stars, particularly because a certain kind of old, bright and blue stars, the blue horizontal branch stars, can only exist if the star it evolves from was born metal-poor.

What a snapshot of galactic evolution this picture is, and how beautiful it is! :D

Ann
Color Commentator

starsurfer
Stellar Cartographer
Posts: 4777
Joined: Thu Mar 15, 2012 7:25 pm

Re: APOD: Stars and Dust Across Corona Australis (2012 Sep 2

Post by starsurfer » Thu Sep 27, 2012 7:28 am

Yet another magnificent masterpiece from the Italian artist! :D

I love the vibrant blue colours and it's cool that one of the many Herbig Haro objects associated with this complex can be seen (the hook shaped thing right of NGC 6729). The other really interesting thing is that although the globular NGC 6723 is more distant than the complex, it doesn't look like it's totally reddened by the dust as it looks more white than golden brown.

The other thing I love about this area of the sky is that it includes objects from two constellations, NGC 6723 is within the boundaries of Sagittarius. Also the image on APOD is slightly cropped, the full frame original image on his website includes a nice ring galaxy to the north, so that also makes this one of the rare areas of the sky that includes all three main deep sky object types!

Marco will certainly continue producing amazing images of the night sky and I can't wait to see what he has up his sleeve! :D

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18805
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

"Southern Wreath"

Post by neufer » Thu Sep 27, 2012 9:42 am

http://en.wikipedia.org/wiki/Corona_Australis#History wrote: <<The Greek astronomer Ptolemy named [the constellation] Στεφάνος νοτιος (Stephanos notios), "Southern Wreath", while other authors associated it with either Sagittarius (having fallen off his head) or Centaurus.

Corona Australis has been associated with the myth of Bacchus and Semele: Jupiter had impregnated Semele, causing Juno to become jealous. Juno convinced Semele to ask Jupiter to appear in his full splendor, which the mortal woman could not handle, causing her to burn. After Bacchus, Semele's unborn child, became an adult and the god of wine, he honored his deceased mother by placing a wreath in the sky.

The indigenous Boorong people of northwestern Victoria saw it as Won, a boomerang thrown by Totyarguil (Altair). The Aranda people of Central Australia saw Corona Australis as a coolamon (wooden basket) carrying a baby, which was accidentally dropped to earth by a group of sky-women dancing in the Milky Way. The impact of the coolamon created Gosses Bluff crater, 175 km west of Alice Springs.>>
http://en.wikipedia.org/wiki/Gosses_Bluff_crater wrote: <<Gosses Bluff (Gosse's Bluff) is thought to be the eroded remnant of an impact crater. It is located in the southern Northern Territory, near the centre of Australia, about 175 km west of Alice Springs and about 212 km to the northeast of Uluru (Ayers Rock). The original crater is thought to have been formed by the impact of an asteroid or comet approximately 142.5 ± 0.8 million years ago, in the earliest Cretaceous, very close to the Jurassic - Cretaceous boundary. The original crater rim has been estimated at about 22 km in diameter, but this has been eroded away. The 5 km diameter, 180 m high crater-like feature, now exposed, is interpreted as the eroded relic of the crater's central uplift. The impact origin of this topographic feature was first proposed in the 1960s, the strongest evidence coming from the abundance of shatter cones. In the past the crater has been the target of petroleum exploration, and two abandoned exploration wells lie near its centre.

The site is known as Tnorala to the Western Arrernte Aboriginal people, and is a sacred place. It is now located in the Tnorala Conservation Reserve. A Western Arrernte story attributes its origins to a cosmic impact: in the Dreaming, a group of celestial women were dancing as stars in the Milky Way. One of the women grew tired and placed her baby in a coolamon (wooden basket). As the women continued dancing, the basket fell and plunged into the earth. The baby fell to the earth and forced the rocks upward, forming the circular mountain range. The baby's parents, the evening and morning star, continue to search for their baby to this day.>>
Last edited by neufer on Thu Sep 27, 2012 12:52 pm, edited 1 time in total.
Art Neuendorffer

User avatar
Indigo_Sunrise
Science Officer
Posts: 438
Joined: Fri Jul 15, 2005 1:40 pm
Location: Md

Re: APOD: Stars and Dust Across Corona Australis (2012 Sep 2

Post by Indigo_Sunrise » Thu Sep 27, 2012 10:27 am

Wonderful APOD! The high resolution version of this image is positively blinding!


8-)
Forget the box, just get outside.

User avatar
orin stepanek
Plutopian
Posts: 7602
Joined: Wed Jul 27, 2005 3:41 pm
Location: Nebraska

Re: APOD: Stars and Dust Across Corona Australis (2012 Sep 2

Post by orin stepanek » Thu Sep 27, 2012 12:10 pm

I like it! :D :clap: :clap: :thumb_up: :thumb_up: :yes:
Orin

Smile today; tomorrow's another day!

Boomer12k
:---[===] *
Posts: 2691
Joined: Sun Apr 22, 2007 12:07 am

Re: APOD: Stars and Dust Across Corona Australis (2012 Sep 2

Post by Boomer12k » Thu Sep 27, 2012 3:49 pm

Looks like a FLY.....A fly throwing up, at that.... :shock:

Beautiful picture!!!!


:---[===] *

User avatar
Beyond
500 Gigaderps
Posts: 6889
Joined: Tue Aug 04, 2009 11:09 am
Location: BEYONDER LAND

Re: APOD: Stars and Dust Across Corona Australis (2012 Sep 2

Post by Beyond » Thu Sep 27, 2012 4:46 pm

Boomer12k wrote:Looks like a FLY.....A fly throwing up, at that.... :shock:

Beautiful picture!!!!


:---[===] *
Nah! The Fly's just sticking it's long tounge out at you. :lol2:
To find the Truth, you must go Beyond.

User avatar
LocalColor
Science Officer
Posts: 266
Joined: Sat Mar 31, 2012 9:11 pm
Location: Central Idaho, USA

Re: APOD: Stars and Dust Across Corona Australis (2012 Sep 2

Post by LocalColor » Thu Sep 27, 2012 4:57 pm

Lovely!

FloridaMike
Science Officer
Posts: 413
Joined: Fri Nov 04, 2011 2:21 pm
Location: Florida, USA

Re: APOD: Stars and Dust Across Corona Australis (2012 Sep 2

Post by FloridaMike » Thu Sep 27, 2012 5:00 pm

Another great photo of "Once and Future Stars".
Certainty is an emotion. So follow your spindle neurons.

User avatar
Moonlady
Selenian
Posts: 665
Joined: Fri Apr 13, 2012 9:06 pm

Re: APOD: Stars and Dust Across Corona Australis (2012 Sep 2

Post by Moonlady » Fri Sep 28, 2012 2:46 am

The globular cluster in the upper right is stunning! Are there globular clusters with much more stars very close together because this one looks like, if they move just a little bit more
tight, they become one big sun!

tmccants2

Re: APOD: Stars and Dust Across Corona Australis (2012 Sep 2

Post by tmccants2 » Fri Sep 28, 2012 3:09 am

What is the small comma-shaped feature below and to the left of the two blue stars near the center of the photograph?

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18805
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: Stars and Dust Across Corona Australis (2012 Sep 2

Post by neufer » Fri Sep 28, 2012 3:43 am

Moonlady wrote:
The globular cluster in the upper right is stunning! Are there globular clusters with much more stars very close together because this one looks like, if they move just a little bit more tight, they become one big sun!
Stable stars can't exist with masses much greater than ~100 solar masses.

(They might become one big black hole, however.)
Art Neuendorffer

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18805
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: Stars and Dust Across Corona Australis (2012 Sep 2

Post by neufer » Fri Sep 28, 2012 4:07 am


tmccants2 wrote:
What is the small comma-shaped feature below and to the left of the two blue stars near the center of the photograph?
http://en.wikipedia.org/wiki/NGC_6729 wrote:
<<NGC 6729 (also known as Caldwell 68) is a reflection/emission nebula in the constellation Corona Australis. It was discovered by Johann Friedrich Julius Schmidt in 1861. This fan-shaped nebula opens from the star R Coronae Australis toward the star T CrA to the south-east. R CrA is a pre-main-sequence star in the Corona Australis molecular complex, one of the closer star-forming regions of the galaxy.>>
Art Neuendorffer

starsurfer
Stellar Cartographer
Posts: 4777
Joined: Thu Mar 15, 2012 7:25 pm

Re: APOD: Stars and Dust Across Corona Australis (2012 Sep 2

Post by starsurfer » Sat Sep 29, 2012 3:24 am

tmccants2 wrote:What is the small comma-shaped feature below and to the left of the two blue stars near the center of the photograph?
This is a Herbig Haro object catalogued as HH 100, it is a jet from a young star. It's strange that the description doesn't make any mention of them as this is one of the few starforming complexes in the southern sky to feature them.