APOD: Star Streams and the Sunflower Galaxy (2010 Sep 11)

[APOD Robot]

Star Streams and the Sunflower Galaxy

Explanation: A bright spiral galaxy of the northern sky, Messier 63 is about 25 million light-years distant in the loyal constellation Canes Venatici. Also cataloged as NGC 5055, the majestic island universe is nearly 100,000 light-years across, about the size of our own Milky Way. Known by the popular moniker, The Sunflower Galaxy, M63 sports a bright yellowish core and sweeping blue spiral arms, streaked with cosmic dust lanes and dotted with pink star forming regions. This deep exposure also reveals an enormous but dim arc extending far into the halo above the brighter galactic plane. A collaboration of professional and amateur astronomers has shown the arc to be consistent with the stellar stream from a smaller satellite galaxy, tidally disrupted as it merged with M63 during the last 5 billion years. Their discovery is part of an increasing body of evidence that the growth of large spirals by cannibalizing smaller galaxies is commonplace in the nearby Universe.

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[mexhunter]

Another extraordinary photo of Jay GaBany.
Grettings
César

[Ann]

This is a very interesting and beautiful image by R Jay GaBany.

Because of my obsession with color, I feel compelled to point out that the color balance of the image is "blue". This is obvious from the color of the two bright stars which are seen to the right of the galaxy in this image. The one which is closest to the galaxy's center from our vantage point is classified as a K0 star by my astronomy software, but the color index of the star clearly shows that its spectral class must be as early as F. The star is bluer than the Sun, and its color index, +0.509 in the Johnson system, suggests a spectral class of F7 or F8. The fact that this star looks blue in today's APOD is reasonable if we use the Sun as a standard of stellar whiteness (which is the right way to do it, in my opinion).

The other bright star, however, is yellower than the Sun, with a color index that suggests a spectral class for this star of late class G. The fact that this star looks blue in the image even though it is yellower than the Sun shows that the color balance of the image is "blue".

But this blue color balance brings out some hugely interesting details in the star streams surrounding the galaxy. In spite of the blue color balance of the image most of the faint star streams surrounding the galaxy are beige in color, with no hint of blue. This shows that these star streams are made up of old stars. Not only is there no star formation going on within the beige-colored star streams, but the stars making up these strems are themselves old and yellow. This suggests to me either that the dwarf galaxy that was shredded and left these star streams behind had had no recent star formation, so that the dwarf galaxy itself was made up entirely of old stars, or else that the shredding of the galaxy happened so long ago that any young blue stars that may have been there at the time must have died since the galaxy was shredded.

If I dare to trust the color balance here, I'd say that the beige rather than grey color of the star streams suggests that the stars in them are not extremely metal-poor. Metal-poor stars are bluer in color than metal-rich ones and would give the star streams a slightly blue-grey tint, rather than a beige one. If the stars are not very metal-poor, then the dwarf galaxy that was shredded may have undergone several episodes of star formation, so that many of the stars it contained had been formed out of gas that had been recycled by the dwarf galaxy's own local supernovae. A more likely scenario is perhaps that the dwarf galaxy itself had been been formed out of a large dense gas cloud that was enriched with heavier elements from the beginning.

I said that many of the star streams are beige in color and show no signs of star formation whatsoever. Other star streams, however, do show signs of blue, attesting to the presence of gas and dust and star formation even in some of these outlying star streams. Below one of the bright stars in the image is a particularly bright patch of blue, which may be an outlying spiral arm of the galaxy itself. And there is what looks like a long, faint bluish arm "below" this bright blue patch, even further out from the main disk of the galaxy.

I have long wondered about a long, very dark "arrow" of dust that seems to cut across the "lower part" of the galaxy's main disk. Does anyone know what this long dark dust structure might be?

Ann

[owlice]

Wow, what a lovely image. And check out all the other galaxies in the background!

Love the write-up, too; "loyal constellation" was a nice touch.

[neufer]

Love the write-up, too; "loyal constellation" was a nice touch.

http://asterisk.apod.com/vie ... 02#p131602

[owlice]

http://asterisk.apod.com/vie ... 02#p131602

No, no! Rather, this!

[orin stepanek]

So many galaxies with so many stars. It would be a shame if we are alone in the universe! Today's photo is worthy of being in a wallpaper collection.

[Ann]

As for the "loyal constellation", it isn't quite clear which one that would be, since there are three dog constellations in the sky. (The Big Dog, the Small Dog and the Hunting Dogs.) And not a single cat constellation! That's unfair! Do we have to settle for the Cheshire Cat? And if so, could someone at least tell me the coordinates of that stellar kitty smiley, please?


A feline cloud in the Earth's atmosphere, for lack of more exalted cats!

Ann

[Beyond]

As for the "loyal constellation", it isn't quite clear which one that would be, since there are three dog constellations in the sky. (The Big Dog, the Small Dog and the Hunting Dogs.) And not a single cat constellation! That's unfair! Do we have to settle for the Cheshire Cat? And if so, could someone at least tell me the coordinates of that stellar kitty smiley, please?

http://farm4.static.flickr.com/3242/293 ... c5e81c.jpg
A feline cloud in the Earth's atmosphere, for lack of more exalted cats!

Ann

Ann, Three Dog Night sang about why there is no "Cat" constellation. They sang that "One" is the loneliest number. So if there was a Cat constellation, it would be very loney Amongst the three dog constellations. Not to mention being very tired all the time from all the chaseing by the dogs. The poor cat constellation would be spending all it's time in a constellation. You wouldn't want a kitty to suffer like that - would you

[MTrethowan]

The lower end of this galaxy has an almost straight line through it like some massive object plowed through the lower portion of the spiral. ?

[neufer]

As for the "loyal constellation", it isn't quite clear which one that would be, since there are three dog constellations in the sky.
(The Big Dog, the Small Dog and the Hunting Dogs.) And not a single cat constellation! That's unfair!

That's about as silly an idea as having an Owl constellation!

[b][size=125]Felis — the cat: Bode's Uranographia atlas (1801)[/size][/b]

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[b]Celestial Atlas of Alexander Jamieson (1822)[/b]

---

“There are more things in heaven and earth, Horatio, Than are dreamt of in your philosophy.”
By Grant Hamilton – 8 January 2010

<<If I must pick one thing about winter that I enjoy, it’s the crisp clear nights — and even in the midst of a semi-urban environment, there’s enough darkness in my neighbourhood that the stars shine brightly above me. So despite the chill downright cold, I took a few extra moments between hauling full personal dumpsters through the snow and to the curb and looked up, up, up. No, I didn’t see any shooting stars (though, it’s always a treat when you do see one, unexpectedly). I did manage to pick out a few half-constellations (the light pollution makes it kind of difficult). But I got the important part — a sense of my own insignificance next to the immensity of the universe.

Constellations, by the way, have always intrigued me. First of all, even during the darkest of rural nights, I’ve never been able to “see” the shapes that they’re supposed to fit. It’s artistic license taken to a colossal extreme. And secondly, it strikes me as a remnant, a holdover from the geocentric view of the universe. I can understand naming stars and planets — even just from a point of view of differentiating them. But assigning stars to groupings based on where we are in a three-dimensional universe seems anachronistically arrogant. That’s like saying the trees you see from your house look like a castle. Sure, maybe, but cross the street, and parallax has changed your point of view. Some of the stars that are in constellations together are so far apart — and so far away from Earth — that some of them have probably already burned out.

But that’s just unromantic of me. I love the spectacle of the stars. I even appreciate the mythology behind the constellations. So try this on for size:

15 Constellations That Are Now Extinct — including: Felis — the cat: A constellation was created by Lalande in 1799 who said:

• “I am very fond of cats. I will let this figure scratch on the chart.
  The starry sky has worried me quite enough in my life, so that now I can have my joke with it.”

There’s a little bit more about Felis here. Or read all about 14 other no-longer-used constellations. Then go out and look at the sky. Make up your own constellations, if you like. The only meanings they have are the ones we give to them. That’s probably enough.>>

[b][color=#FF0000]Noctua on the Celestial Atlas of Alexander Jamieson (1822)[/color][/b]

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<<"Turdus Solitarius" was introduced in 1776 by the French astronomer Pierre-Charles Le Monnier in a paper titled “Constellation du Solitaire” in the Mémoires of the French Royal Academy of Sciences. The historian R. H. Allen said in his book Star Names that the constellation represented the Rodrigues Solitaire, an extinct flightless bird similar to the Dodo, but this seems to be a misunderstanding. Bode changed its name to Turdus Solitarius in his Uranographia atlas of 1801.

The British scientist Thomas Young renamed the constellation the Mocking Bird on his star map of 1806, while the English amateur astronomer Alexander Jamieson changed it into Noctua, the owl, on his Celestial Atlas of 1822. Jamieson said he thought it was strange that no such bird had previously been placed among the constellations “considering the frequency it is met with on all Egyptian monuments”. Before it flew from the sky, the constellation occupied an area at the tip of the Hydra’s tail next to Libra. >>

LEO: the second-largest living cat

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<<The lion (Panthera leo) is one of the four big cats in the genus Panthera, and a member of the family Felidae. With some males exceeding 250 kg (550 lb) in weight, it is the second-largest living cat after the tiger. Lions are unusually social compared to other cats.>>

[Ann]

They shouldn't have gotten rid of Felis the Cat constellation! Having a Leo constellation is no compensation!

Wikipedia says that Felis the Cat was located between Antlia and Hydra. There is a bunch of fourth to sixth magnitude stars along the border of Antlia and Hydra. Perhaps the Cat used to be them. Alpha Hydra is a fourth magnitude yellow-orange K5 type star, not my favorite, but I have to wonder if that star once belonged to Felis the Cat. From now on I'm going to think of that star as one of the cat's yellow eyes.

Ann

[owlice]

As for the "loyal constellation", it isn't quite clear which one that would be, since there are three dog constellations in the sky.

I think the context makes it pretty clear here.

That's about as silly an idea as having an Owl constellation!

Since owls are always in the night sky, there is no need for an Owl constellation.

[neufer]

They shouldn't have gotten rid of Felis the Cat constellation! Having a Leo constellation is no compensation!

[size=200]FELIS the CAT[/size]

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There are plenty of Lynx to cats!

<<Lynx is a constellation in the northern sky, introduced in the 17th century by Johannes Hevelius. It is named after the lynx, a genus of cat. It is a very faint constellation; its brightest stars form a zigzag line. Johannes Hevelius defined the constellation in the 17th century because he wanted to fill the open gap between the constellations Ursa Major and Auriga. He supposedly named it Lynx because of its faintness: only the lynx-eyed (or those of good sight) would have been able to recognise it.>>

[img3="FELIS lies about where the letters "HYDRA" are"]http://www.daviddarling.info/images/Alphard.png[/img3]

Wikipedia says that Felis the Cat was located between Antlia and Hydra. There is a bunch of fourth to sixth magnitude stars along the border of Antlia and Hydra. Perhaps the Cat used to be them. Alpha Hydra is a fourth magnitude yellow-orange K5 type star, not my favorite, but I have to wonder if that star once belonged to Felis the Cat. From now on I'm going to think of that star as one of the cat's yellow eyes.

[c]Alphard!
The "backbone of the Serpent!"
The "heart of the snake!"[/c]

<<Alphard (α Hya / Alpha Hydrae) is the brightest star in the constellation Hydra. The name Alphard is from the Arabic الفرد (al-fard), "the solitary one", there being no other bright stars near it. It was also known as the "backbone of the Serpent" to the Arabs. In ancient China it formed part of an asterism called the "red bird". The European astronomer Tycho Brahe dubbed it Cor Hydræ, the heart of the snake.

Alphard has three times the mass of the Sun. The estimated age of this star is 420 million years and it has evolved away from the main sequence to become a giant star with a spectral classification of K3 and luminosity class between II and III. The angular diameter of this star has been measured using long baseline interferometry, yielding a value of 9.09 ± 0.09 milliarcseconds. It has expanded to 50 times the radius of the Sun.

The spectrum of this star shows a mild excess of barium, an element that is normally produced by the s-process of nucleosynthesis. Typically a barium star belongs to a binary system and the anomalies in abundances are explained by mass transfer from a companion white dwarf star.

Precise radial velocity measurements have shown variations in the stellar radial velocities and spectral line profiles. The oscillations are multi-periodic with periods from several hours up to several days. The short-term oscillations were assumed to be a result of stellar pulsations, similar to the solar ones. A correlation between the variations in the asymmetry of the spectral line profile and the radial velocity has also been found. The multi-periodic oscillations make HD 81797 (Alphard) an object of interest for asteroseismologic investigations.>>

http://en.wikipedia.org/wiki/Former_constellations

[owlice]

The "backbone of the Serpent!"
The "heart of the snake!"

Wow. I know just who this refers to!!

[neufer]

That's about as silly an idea as having an Owl constellation!

Since owls are always in the night sky, there is no need for an Owl constellation.

• “The starry sky has worried me quite enough in my life,
  so that now I can have my joke with it.”

[neufer]

The "backbone of the Serpent!"
The "heart of the snake!"

Wow. I know just who this refers to!!

DUMBO GUMBO

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[img3=""Oh! I understand you very well," said the little prince.
"But why do you always speak in riddles?"

"I solve them all," said the snake.

And they were both silent."]http://blog.joins.com/usr/h/a/hansha/67 ... 819%29.jpg[/img3]

<<Since its publication _Le Petit Prince_ has been translated into over 180 languages, including Congolese and Sardinian. In 2005, the book was translated into Toba, an indigenous language of northern Argentina, as So Shiyaxauolec Nta'a. It was the first book translated into this language since the New Testament Bible. Anthropologist Florence Tola commenting on the suitability of the work for Toban translation said there was "nothing strange [in that] the Little Prince speaks with a snake or a fox and travel among the stars, it fits perfectly to the Toba mythology." The book is one of few modern books to be translated into Latin, as Regulus Vel Pueri Soli Sapiunt.>>

[owlice]

I came upon a very charming broadcast of the opera The Little Prince late one night; I did not know of the opera until then. It was a lovely production, and gee, I really should find it on DVD so I can see the beginning of it!

[neufer]

I came upon a very charming broadcast of the opera The Little Prince late one night; I did not know of the opera until then. It was a lovely production, and gee, I really should find it on DVD so I can see the beginning of it!

I'm assuming you are not talking about the 1974 musical movie:
http://www.imdb.com/title/tt0071762/
-------------------------------------------------
http://www.imdb.com/title/tt0438166/

http://www.amazon.com/dp/B0007TFH3O?tag=imdb-adbox

http://www.lepetitprince.com/#/?lng=uk

[owlice]

neufer, you are a prince; thank you!!! In my Amazon cart; $11 very well-spent! This is a really lovely production, beautifully sung (I even like the soprano! ), with a simple setting that is nevertheless wonderfully fitting and visually appealing, fine music, and thoroughly charming. Thanks!!!

[Ann]

Sorry, I didn't mean to imply that Alphard would ever have been the alpha star of the Felis constellation. The Cat's alpha star would be a fourth magnitude star close to the border between Antlia and Hydra, but Alphard is a second magnitude star, not a fourth magnitude one. And still more importantly, it isn't close to the constellation Antlia.

No, the star I meant to say was Alpha Antlia. That one is a fourth magnitude star, close to the constellation of Hydra, and that one may have been one of the Cat's yellow eyes.

And having a Lynx constellation is still no compensation for the lack of a Cat one! Really, neufer. If we got rid of all the dog constellations, should I tell you not to pout because we still have a Wolf constellation (Lupus)? And hey, there is even a Fox up there! Vulpecula! Who needs Canis Major, Canis MInor and Canes Venatici up there when we have already got a Wolf and a Fox?

I want a cat in the sky! A cat!


Like this one!

Not that I don't like lynxes, because I really like them a lot, but...!!!

I have an idea. With all the dogs up there, how about one of the Dog constellations is changed to a Cat constellation? How about Canis Minor? Then we would still have Canis Major and Canes Venatici, but we would also have Felis the Cat! Procyon would be its alpha star, and Beta Canis Majoris would be the Cat's "other eye", a blue one! They say that cats with one blue and one yellow eye may be deaf. Well, who cares, there aren't that many sounds in space, I think.

Ann

[mpharo]

The Sunflower Galaxy

[Beyond]

I wondered why the baseball kept getting bigger. Then it hit me.

Gee owlice, owls have very good hearing. I would have thought the crack of the bat wooda given it away.

[neufer]

I want a cat in the sky! A cat! Like this one!

[b][color=#0000FF][i]To Thebes in Baeotia streight a cruell beast she sent, Which wrought the bane of many a Wight. The countryfolk did feed Him with their cattell and themselves,[/i][/color][/b] - Ovid's Metamorphosis.

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You call that a CAT!!! It's more like a gigantic child eating Teumessian fox

<<In Greek mythology, the Teumessian fox or Cadmean vixen, was a gigantic fox that was destined never to be caught. The fox was one of the children of Echidna. It was said that it had been sent by the gods (perhaps Dionysus) to prey upon the children of Thebes as a punishment for some national crime. Creon, the then Regent of Thebes, set Amphitryon the impossible task of destroying this beast. He discovered an apparently perfect solution to the problem by fetching the magical dog Laelaps, who was destined to catch everything it chased. Zeus, faced with an inevitable contradiction in fate due to their mutually excluding abilities, turned the two beasts into stone.

The pair were cast into the stars, and will remain there forever more.>>

<<Canis Minor is a small constellation containing only two bright stars, Procyon and Gomeisa. Procyon (προκύον) means "before the dog" in Greek, as it rises an hour before the 'Dog Star', Sirius, of Canis Major. Procyon also goes by the Arabic-derived name Elgomaisa (الغميصاء al-ghumaisa’) "the bleary-eyed (woman)", in contrast to العبور "the teary-eyed (woman)", which is Sirius. Canis Minor is sometimes connected with the Teumessian Fox, a beast turned into stone with its hunter, Laelaps, by Zeus, who placed them in heaven as Canis Major (Laelaps) and Canis Minor (Teumessian Fox).>>

I have an idea. With all the dogs up there, how about one of the Dog constellations is changed to a Cat constellation? How about Canis Minor? Then we would still have Canis Major and Canes Venatici, but we would also have Felis the Cat! Procyon would be its alpha star, and Beta Canis Majoris would be the Cat's "other eye", a blue one! They say that cats with one blue and one yellow eye may be deaf. Well, who cares, there aren't that many sounds in space, I think.

Procyon is a white F5 star

<<Procyon is a genus of nocturnal mammals, comprising three species commonly known as raccoons, in the family Procyonidae. The most familiar species, the Common Raccoon (P. lotor), is often known simply as "the" raccoon, as the two other raccoon species in the genus are native only to the tropics and are considerably lesser-known.>>

The "cat" or fox or raccoon or "the bleary-eyed woman" (or whatever) gets to ride a unicorn:

[img3="Monoceros, Canis Major and Canis Minor, 1729.
"Atlas Coelestis", by John Flamsteed (1646-1710)"]http://images.imagestate.com/Watermark/1632986.jpg[/img3]

• THE SEVENTH BOOKE of Ovid's Metamorphosis.
  The first translation into English -
  credited to Arthur Golding
  
  
  To Thebes in Baeotia streight a cruell beast she sent,
  Which wrought the bane of many a Wight. The countryfolk did feed
  Him with their cattell and themselves, untill (as was agreed)
  That all we youthfull Gentlemen that dwelled there about
  Assembling pitcht our corded toyles the champion fields throughout.
  But Net ne toyle was none so hie that could his wightnesse stop,
  He mounted over at his ease the highest of the top.
  Then everie man let slip their Grewnds, but he them all outstript
  And even as nimbly as a birde in daliance from them whipt.
  Then all the field desired me to let my Laelaps go: ..
  (The Grewnd that Procris unto me did give was named so)
  Who strugling for to wrest his necke already from the band
  Did stretch his collar. Scarsly had we let him off of hand
  But that where Laelaps was become we could not understand.
  The print remained of his feete upon the parched sand,
  But he was clearly out of sight. Was never Dart I trow,
  Nor Pellet from enforced Sling, nor shaft from Cretish bow,
  That flew more swift than he did runne. There was not farre fro thence
  About the middle of the Laund a rising ground, from whence
  A man might overlooke the fieldes. I gate me to the knap ...
  Of this same hill, and there beheld of this straunge course the hap
  In which the beast seemes one while caught, and were a man would think,
  Doth quickly give the Grewnd the slip, and from his bighting shrink:
  And like a wilie Foxe he runnes not forth directly out,
  Nor makes a windlasse over all the champion fieldes about,
  But doubling and indenting still avoydes his enmies lips,
  And turning short, as swift about as spinning wheele he whips,
  To disappoint the snatch. The Grewnd pursuing at an inch
  Doth cote him, never losing ground: but likely still to pinch
  Is at the sodaine shifted off. Continually he snatches ...
  In vaine: for nothing in his mouth save only Aire he latches.
  Then thought I for to trie what helpe my Dart at neede could show.
  Which as I charged in my hand by levell aime to throw,
  And set my fingars to the thongs, I lifting from bylow
  Mine eies, did looke right forth againe, and straight amids the field
  (A wondrous thing) two Images of Marble I beheld:
  Of which ye would have thought the t'one had fled on still apace
  And that with open barking mouth the tother did him chase.
  In faith it was the will of God (at least if any Goddes
  Had care of them) that in their pace there should be found none oddes. ...