Comments and questions about the
APOD on the main view screen.
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TrinitySite 555
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by TrinitySite 555 » Mon Mar 26, 2012 11:35 am
The pitcures and discussion reference M82 and the Superwind was very informative today. However, it gave me some pause when it discussed the "close brush" with it's neighbor, M81. Does anyone know what the distance is that separates these two?
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neufer
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by neufer » Mon Mar 26, 2012 11:41 am
Art Neuendorffer
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copper5817
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by copper5817 » Mon Mar 26, 2012 12:00 pm
It kinda looks like the "supergalactic wind" is just a nebula which as far closer to us than the galaxy and just happens to be in the same sightline...
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rstevenson
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by rstevenson » Mon Mar 26, 2012 12:13 pm
According to
this Wikipedia page, the apparent visual separation is about 130,000 light years, but the actual distance between them is more like 300,000 light years. Their most recent "close brush" happened about 200 Myr ago, more or less.
Rob
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neufer
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by neufer » Mon Mar 26, 2012 12:16 pm
APOD Robot wrote:
Huge Gamma Ray Bubbles Found Around Milky Way
Explanation: Did you know that our Milky Way Galaxy has huge bubbles emitting gamma rays from the direction of the galactic center? Neither did anybody. As the data from the Earth-orbiting
Fermi satellite began
acuminating over
the past two
years, however, a large and unusual feature toward
our Galaxy's center became increasingly evident. The
two bubbles are visible together as the red and white spotted oval surrounding the center of the above all sky image,
released yesterday. The
plane of our Galaxy runs horizontally across the image center. Assuming
the bubbles emanate from our Galaxy's center, the scale of the bubbles is huge, rivaling the entire Galaxy in size, and spanning about 50,000
light years from top to bottom. Earlier indications of the bubbles has been found on existing all sky maps in the
radio,
microwave, and
X-ray. The cause of the bubbles is
presently unknown, but will likely be researched for years to come.
Art Neuendorffer
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neufer
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by neufer » Mon Mar 26, 2012 12:29 pm
http://apod.nasa.gov/apod/ap060414.html wrote:
Smoke from the Cigar Galaxy
<<Explanation: Very bright in infrared light, well-known starburst galaxy M82's popular name describes its suggestive shape seen at visible wavelengths - The Cigar Galaxy. Ironically, M82's fantastic appearance in this Spitzer Space Telescope image really is due to cosmic "smoke" - the infrared emission of exented dust features blown by stellar winds from M82's luminous, central star forming regions. The false-color view highlights a component of dust emission from complex carbon molecules called polycyclic aromatic hydrocarbons or PAHs. PAHs are also seen in star forming regions throughout our own, much calmer, Milky Way Galaxy and are products of combustion on planet Earth. Likely triggered by interactions with nearby galaxy M81, M82's intense star formation activity appears to be blowing out immense clouds of dust and PAHs extending nearly 20,000 light-years both above and below the galactic plane. M82 is about 12 million light-years away in the constellation Ursa Major. >>
Art Neuendorffer
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orin stepanek
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by orin stepanek » Mon Mar 26, 2012 12:34 pm
Interesting looking galaxy; but not very pretty!
It's kind of like the ugly duckling of galaxies!
Maybe it will evolve into a beautiful swan!
Orin
Smile today; tomorrow's another day!
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neufer
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by neufer » Mon Mar 26, 2012 1:18 pm
orin stepanek wrote:
Interesting looking galaxy; but not very pretty!
It's kind of like the ugly duckling of galaxies!
Maybe it will evolve into a beautiful swan!
http://www.parks.tas.gov.au/index.aspx?base=1074 wrote:
<<The decline in populations of Swan galaxiids (Galaxias fontanus) has been attributed to predation by introduced fish such as brown trout and redfin perch. The endemic Swan galaxiid also has a fairly restricted, natural range, only being found in the Swan and Macquarie river tributaries on Tasmania's east coast. Any changes to its habitat could have a disastrous effect on the fish.
To prevent the Swan galaxiid being eaten to extinction by these introduced predators, since 1989 the Inland Fisheries Commission has been relocating them to areas where these predators do not occur. Sites chosen usually have natural barriers, such as waterfalls, to prevent the trout and perch from reaching them. Provided people do not interfere by introducing exotic fish to these particular sites the Swan galaxiid has a good chance of survival.>>
Art Neuendorffer
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neptunium
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by neptunium » Mon Mar 26, 2012 3:02 pm
Could M82 be a spiral galaxy of some sort but classified as irregular due to its texture and shape? It seems to me that this galaxy is seen more edge-on.
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Sandstone
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by Sandstone » Mon Mar 26, 2012 4:11 pm
neufer wrote:
<<The decline in populations of Swan galaxiids (Galaxias fontanus) has been...
Neufer,
From where do these gems of thought and wondrous information spring forth???
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bub4280
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by bub4280 » Mon Mar 26, 2012 4:41 pm
Those Clouds take a shape similar to suspected dark matter lobes.
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jisles
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by jisles » Mon Mar 26, 2012 5:12 pm
The galaxy is not 'towards' the constellation Ursa Major. APOD captions regularly make this mistake. It's IN the constellation Ursa Major. Constellations comprise everything within an irregularly-outlined cone, stretching to infinity, whose apex is at the observer's eye. I love APOD though!
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Beyond
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by Beyond » Mon Mar 26, 2012 6:40 pm
Sandstone wrote:neufer wrote:
<<The decline in populations of Swan galaxiids (Galaxias fontanus) has been...
Neufer,
From where do these gems of thought and wondrous information spring forth???
Oh my
To find the Truth, you must go Beyond.
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ta152h0
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by ta152h0 » Mon Mar 26, 2012 7:52 pm
Apparently Mr jisles is another nit picker who gives a candela... pass the ice cold one around ...
Wolf Kotenberg
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neufer
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by neufer » Mon Mar 26, 2012 9:50 pm
Beyond wrote:Sandstone wrote:neufer wrote:
<<The decline in populations of Swan galaxiids (Galaxias fontanus) has been...
Neufer,
From where do these gems of thought and wondrous information spring forth???
Oh my
I'll have you know, Beyond, that Swan galaxiids
are
NOT related to
candiru Art Neuendorffer
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Beyond
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by Beyond » Mon Mar 26, 2012 10:53 pm
Only ifin i's wants to.
To find the Truth, you must go Beyond.
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Sandstone
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by Sandstone » Tue Mar 27, 2012 1:17 am
jisles wrote:The galaxy is not 'towards' the constellation Ursa Major. APOD captions regularly make this mistake. It's IN the constellation Ursa Major. Constellations comprise everything within an irregularly-outlined cone, stretching to infinity, whose apex is at the observer's eye. I love APOD though!
Hmmmm... and how does one define "cone", then?
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Chris Peterson
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by Chris Peterson » Tue Mar 27, 2012 3:59 am
Sandstone wrote:jisles wrote:The galaxy is not 'towards' the constellation Ursa Major. APOD captions regularly make this mistake. It's IN the constellation Ursa Major. Constellations comprise everything within an irregularly-outlined cone, stretching to infinity, whose apex is at the observer's eye. I love APOD though!
Hmmmm... and how does one define "cone", then?
Good point... my dictionary includes
a solid bounded by a circular or other closed plane base and the surface formed by line segments joining every point of the boundary of the base to a common vertex
which suggests to me that the usage given by jisles is acceptable.
Last edited by
Chris Peterson on Tue Mar 27, 2012 4:51 am, edited 1 time in total.
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TNT
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by TNT » Tue Mar 27, 2012 4:08 am
jisles wrote:The galaxy is not 'towards' the constellation Ursa Major. APOD captions regularly make this mistake. It's IN the constellation Ursa Major. Constellations comprise everything within an irregularly-outlined cone, stretching to infinity, whose apex is at the observer's eye. I love APOD though!
That seems correct to me. If an object is said to be in a certain area, wouldn't it also be seen
towards that area? And where are you getting an irregularly outlined cone? It would be more logical to say that it is an irregularly shaped figure or plane, as it appears two-dimensional. I don't think I've even seen an irregularly outlined cone before.
The following statement is true.
The above statement is false.
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Chris Peterson
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by Chris Peterson » Tue Mar 27, 2012 4:50 am
TNT wrote:jisles wrote:The galaxy is not 'towards' the constellation Ursa Major. APOD captions regularly make this mistake. It's IN the constellation Ursa Major. Constellations comprise everything within an irregularly-outlined cone, stretching to infinity, whose apex is at the observer's eye. I love APOD though!
That seems correct to me. If an object is said to be in a certain area, wouldn't it also be seen
towards that area? And where are you getting an irregularly outlined cone? It would be more logical to say that it is an irregularly shaped figure or plane, as it appears two-dimensional. I don't think I've even seen an irregularly outlined cone before.
As I noted, a cone is not limited to a solid with a circular base- the base can be any polygon, and calling that shape "an irregularly outlined cone" seems clear enough. Technically, an object is always "in" a constellation, not "towards" it. And that means that the object lies in the volume defined by the so-called irregularly outlined cone. Personally, I don't have much problem with a caption that says something is "towards" a constellation, but that usage isn't very conventional.
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Sandstone
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by Sandstone » Tue Mar 27, 2012 6:59 am
On "Maxwell Smart", the "Cone of Silence" was clearly dome shaped.
Last edited by
Sandstone on Wed Mar 28, 2012 4:55 am, edited 1 time in total.
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Beyond
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by Beyond » Tue Mar 27, 2012 12:37 pm
And it worked so well that they couldn't hear each other
To find the Truth, you must go Beyond.
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Chris Peterson
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by Chris Peterson » Tue Mar 27, 2012 2:34 pm
Sandstone wrote:I've scoured the finest mathematical resources known to humanity, and a cone is... well... a cone. You know, one of those round pointy things.
The error you made was in scouring "mathematical resources". The APOD caption isn't a mathematical discourse, nor are the discussions here. And a quick perusal of ordinary English language dictionaries will immediately reveal that a cone
can be something other than "one of those round pointy things".
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neufer
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by neufer » Tue Mar 27, 2012 2:48 pm
TNT wrote:jisles wrote:
The galaxy is not 'towards' the constellation Ursa Major. APOD captions regularly make this mistake.
It's IN the constellation Ursa Major. Constellations comprise everything within an irregularly-outlined cone, stretching to infinity, whose apex is at the observer's eye. I love APOD though!
That seems correct to me. If an object is said to be in a certain area, wouldn't it also be seen
towards that area?
Most non-astronomers would have a good idea of what 'towards' the constellation Ursa Major or Big Dipper generally means.
However, few would know, off hand, what constitutes the
gerrymandered district "IN the constellation Ursa Major."
Art Neuendorffer
M82: Galaxy with a Supergalactic Wind
