APOD: Orion over the Austrian Alps (2019 Jan 23)

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APOD: Orion over the Austrian Alps (2019 Jan 23)

Post by APOD Robot » Wed Jan 23, 2019 5:07 am

Image Orion over the Austrian Alps

Explanation: Do you recognize this constellation? Through the icicles and past the mountains is Orion, one of the most identifiable star groupings on the sky and an icon familiar to humanity for over 30,000 years. Orion has looked pretty much the same during the past 50,000 years and should continue to look the same for many thousands of years into the future. Orion is quite prominent in the sky this time of year, a recurring sign of (modern) winter in Earth's northern hemisphere and summer in the south. Pictured, Orion was captured recently above the Austrian Alps in a composite of seven images taken by the same camera in the same location during the same night. Below and slightly to the right of Orion's three-star belt is the Orion Nebula, while the four bright stars surrounding the belt are, clockwise from the upper left, Betelgeuse, Bellatrix, Rigel, and Saiph.

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Re: APOD: Orion over the Austrian Alps (2019 Jan 23)

Post by JohnD » Wed Jan 23, 2019 8:47 am

Re Composite pics This is a "composite of seven images taken by the same camera in the same location during the same night."

So not artificial, but art! Nice one!
John

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Re: APOD: Orion over the Austrian Alps (2019 Jan 23)

Post by heehaw » Wed Jan 23, 2019 10:19 am

Orion is magnificent, and is the first constellation (apart from the big dipper) that I suddenly recognized, as a teenager. With city lights, how many kids are deprived of the night sky today?

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Re: APOD: Orion over the Austrian Alps (2019 Jan 23)

Post by Ann » Wed Jan 23, 2019 10:25 am

Stunningly beautiful. :D And cold-looking. I sympathize, because the weather has turned very cold here. :(

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Re: APOD: Orion over the Austrian Alps (2019 Jan 23)

Post by Guest » Wed Jan 23, 2019 12:28 pm

I think this photo is a fake. I was told Orion always comes up on its side. Being so close to the horizon, wouldn’t it show more sideways?

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Re: APOD: Orion over the Austrian Alps (2019 Jan 23)

Post by orin stepanek » Wed Jan 23, 2019 1:05 pm

I like Orion! One of my favorite constellations; easy to find; and always beautiful! :thumb_up: :thumb_up: :-D
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Re: APOD: Orion over the Austrian Alps (2019 Jan 23)

Post by Cousin Ricky » Wed Jan 23, 2019 3:54 pm

Guest wrote:
Wed Jan 23, 2019 12:28 pm
I think this photo is a fake. I was told Orion always comes up on its side. Being so close to the horizon, wouldn’t it show more sideways?
That depends on one’s latitude. This composite photo was taken near Rakousko, Austria, which is at 47°N, where Orion never gets higher than halfway up in the sky. It still looks a bit high low [edited] in this photo, but it is not clear where the horizon is, and camera lens distortion can also exaggerate the size of objects away from the horizon, which, in the absence of other size cues, would have the effect of making Orion look lower than it really is.
Last edited by Cousin Ricky on Thu Jan 24, 2019 12:28 pm, edited 1 time in total.

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Re: APOD: Orion over the Austrian Alps (2019 Jan 23)

Post by Cousin Ricky » Wed Jan 23, 2019 3:58 pm

APOD Robot wrote:
Wed Jan 23, 2019 5:07 am
Orion has looked pretty much the same during the past 50,000 years and should continue to look the same for many thousands of years into the future.
Are we that sure that Betelgeuse won’t blow sooner than thousands of years from now?

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Re: APOD: Orion over the Austrian Alps (2019 Jan 23)

Post by mostly cloudy » Wed Jan 23, 2019 8:34 pm

Cousin Ricky wrote:
Wed Jan 23, 2019 3:54 pm
Guest wrote:
Wed Jan 23, 2019 12:28 pm
I think this photo is a fake. I was told Orion always comes up on its side. Being so close to the horizon, wouldn’t it show more sideways?
That depends on one’s latitude. This composite photo was taken near Rakousko, Austria, which is at 47°N, where Orion never gets higher than halfway up in the sky. It still looks a bit high in this photo, but it is not clear where the horizon is, and camera lens distortion can also exaggerate the size of objects away from the horizon, which, in the absence of other size cues, would have the effect of making Orion look lower than it really is.
We’re at 47 north near Seattle, and Orion looks just right, allowing for our nearly flat horizon and those spectacular Austrian mountains. Wonderful image!

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Re: APOD: Orion over the Austrian Alps (2019 Jan 23)

Post by BDanielMayfield » Wed Jan 23, 2019 8:48 pm

Cousin Ricky wrote:
Wed Jan 23, 2019 3:58 pm
APOD Robot wrote:
Wed Jan 23, 2019 5:07 am
Orion has looked pretty much the same during the past 50,000 years and should continue to look the same for many thousands of years into the future.
Are we that sure that Betelgeuse won’t blow sooner than thousands of years from now?
Good point. No, we can't even be sure that Betelgeuse hasn't already blown up.
The time until Betelgeuse explodes depends on the predicted initial conditions and on the estimate of the time already spent as a red supergiant. The total lifetime from the start of the red supergiant phase to core collapse varies from about 300,000 years for a rotating 25 M☉ star, 550,000 years for a rotating 20 M☉ star, and up to a million years for a non-rotating 15 M☉ star. Given the estimated time since Betelgeuse became a red supergiant, estimates of its remaining lifetime range from a "best guess" of under 100,000 years for a non-rotating 20 M☉ model to far longer for rotating models or lower-mass stars.
So assuming that the "best guess" of less than 100,000 years is correct and that this star is about 600 light years away the odds that it has already popped is more than 0.6%.
"Happy are the peaceable ... "

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Re: APOD: Orion over the Austrian Alps (2019 Jan 23)

Post by Ann » Wed Jan 23, 2019 11:30 pm

BDanielMayfield wrote:
Wed Jan 23, 2019 8:48 pm
Cousin Ricky wrote:
Wed Jan 23, 2019 3:58 pm
APOD Robot wrote:
Wed Jan 23, 2019 5:07 am
Orion has looked pretty much the same during the past 50,000 years and should continue to look the same for many thousands of years into the future.
Are we that sure that Betelgeuse won’t blow sooner than thousands of years from now?
Good point. No, we can't even be sure that Betelgeuse hasn't already blown up.
The time until Betelgeuse explodes depends on the predicted initial conditions and on the estimate of the time already spent as a red supergiant. The total lifetime from the start of the red supergiant phase to core collapse varies from about 300,000 years for a rotating 25 M☉ star, 550,000 years for a rotating 20 M☉ star, and up to a million years for a non-rotating 15 M☉ star. Given the estimated time since Betelgeuse became a red supergiant, estimates of its remaining lifetime range from a "best guess" of under 100,000 years for a non-rotating 20 M☉ model to far longer for rotating models or lower-mass stars.
So assuming that the "best guess" of less than 100,000 years is correct and that this star is about 600 light years away the odds that it has already popped is more than 0.6%.
Which means that the odds that it hasn't already popped are about 99.4%.

Jim Kaler has a lot of interesting (but quite uncertain) info about Betelgeuse.
Jim Kaler wrote:

The star's distance is a problem and a puzzle (true for all the other parameters as well). Direct parallax measures from space, using the most modern results, give 495 light years, whereas the parallax using the star's natural radio emission gives 640 light years. At a compromise distance of 570 light years, and allowing for a lot of infrared radiation and for absorption of light by circumstellar dust, the luminosity comes in at 85,000 times that of the Sun, considerably more than comes out of Antares. At the larger distance, luminosity boosts up to 105,000 Suns.
...
Moreover, because of changes in gaseous transparency, the "size" of the star depends on the color of observation. Long-wave infrared measures give a vastly larger radius of up to 5 AU and greater, as big as the orbit of Jupiter, while shorter-wave infrared light gives as small as 3 AU. Moreover still, infrared measures reveal Betelgeuse to be shrinking (by some 15 percent over about 20 years), and other measures show that the star is not even round, but somewhat oval.
...
Whatever the actual numbers, Betelgeuse is clearly a highly evolved star, one whose central hydrogen fuel supply has run out. As a result, the core has contracted into a hot dense state, and the outer portions swelled outward. We do not really know the star's condition at the moment, but the odds are that it is now in the process of fusing helium into carbon and oxygen in its core.

From theory, its initial mass should have fallen somewhere around 18 or 19 times that of the Sun. Starting life as hot, blue, class O star only around 10 million years ago, Betelgeuse will fuse elements through neon, magnesium, sodium, and silicon all the way to iron. The core will then collapse, causing the star to blow up as a supernova, most likely leaving a compact neutron star about the size of a small town behind.

If it were to explode today, it would become as bright as a gibbous Moon, would cast strong shadows on the ground, and would be seen easily in full daylight.
So Jim Kaler's best guess is that the initial mass of Betelgeuse was 18 to 19 solar masses. That's huge, but it is no record breaker by any means. If the uncertain parallax of "middle Belt star" Alnilam is correct, this blue supergiant is so bright that its initial mass may have been some 40 solar masses, double that of Betelgeuse.

We have of course every reason to believe that Betelgeuse is going to explode as a supernova, but we can't know when it will happen. My amateur opinion is that it is fun to speculate, but downright meaningless to "keep watching Betelgeuse and waiting for it to explode".

Supernovas are rare. No supernova in our own galaxy has been readily visible to the naked eye since 1604. The brightest Milky Way supernova in recorded history may have been the supernova of 1006 in Lupus. According to Wikipedia, this probable Type Ia supernova exploded at a distance of some 7,200 light-years from the Earth, much, much farther away than Betelgeuse.

In my opinion, the chances that Betelgeuse will obligingly explode within the next 100 years or so at a distance of just some 600 light-years away and putting on a cosmic light show that has never been seen before in recorded human history, are slim.

Ann
Last edited by Ann on Thu Jan 24, 2019 1:48 am, edited 1 time in total.
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Re: APOD: Orion over the Austrian Alps (2019 Jan 23)

Post by Boomer12k » Thu Jan 24, 2019 1:46 am

Wonderful image....framed with ice...

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Re: APOD: Orion over the Austrian Alps (2019 Jan 23)

Post by MarkBour » Thu Jan 24, 2019 3:12 am

A lovely image of Orion. I can see Barnard's Loop at the left.
I love how the surrounding ice totally changes the feeling I get when looking at the constellation.
Was the photographer positioned in a cave, perhaps?
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Re: APOD: Orion over the Austrian Alps (2019 Jan 23)

Post by phrankj@cinderzelda.com » Sun Jan 27, 2019 12:22 am

The explanation states " Below and slightly to the right of Orion's three-star belt is the Orion Nebula" and yet I am sure the nebula is to the left, as stated in the explanation when you click on the "Orion Nebula" link.

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Re: APOD: Orion over the Austrian Alps (2019 Jan 23)

Post by Ann » Sun Jan 27, 2019 5:18 am

phrankj@cinderzelda.com wrote:
Sun Jan 27, 2019 12:22 am
The explanation states " Below and slightly to the right of Orion's three-star belt is the Orion Nebula" and yet I am sure the nebula is to the left, as stated in the explanation when you click on the "Orion Nebula" link.



















I have just googled "Orion widefield" and actually most images show the Orion Nebula as located to the right of the three Belt stars. The picture at right is a typical example.

But there are also a few pictures where the Orion Nebula is located to the left of the Belt stars, as in the picture at left.

I know that when I see Orion rising in the east, the Orion Nebula is to the right of the Belt stars. But when Orion is sinking in the west, it "tips over" to the right, like this sign, making the Orion nebula be located to the left of the Belt stars. This "tipping over" movement in the sky (which has everything to do with the Earth's movement, of course) seemingly shifts the Orion Nebula first to the right and then to the left of the Belt stars.

There is no right and left in space. We can only talk about right and left as seen from our own vantage point on Earth.

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Re: APOD: Orion over the Austrian Alps (2019 Jan 23)

Post by Nitpicker » Sun Jan 27, 2019 8:15 am

phrankj@cinderzelda.com wrote:
Sun Jan 27, 2019 12:22 am
The explanation states " Below and slightly to the right of Orion's three-star belt is the Orion Nebula" and yet I am sure the nebula is to the left, as stated in the explanation when you click on the "Orion Nebula" link.
It is below and slightly to the right relative to the frame of this APOD image.