APOD: W5: Pillars of Star Formation (2014 Dec 16)

[APOD Robot]

W5: Pillars of Star Formation

Explanation: How do stars form? Images of the star forming region W5 like those in the infrared by NASA's Wide Field Infrared Survey Explorer (WISE) satellite provide clear clues with indications that massive stars near the center of empty cavities are older than stars near the edges. A likely reason for this is that the older stars in the center are actually triggering the formation of the younger edge stars. The triggered star formation occurs when hot outflowing gas compresses cooler gas into knots dense enough to gravitationally contract into stars. In the featured scientifically-colored infrared image, spectacular pillars, left slowly evaporating from the hot outflowing gas, provide further visual clues. W5 is also known as IC 1848, and together with IC 1805 form a complex region of star formation popularly dubbed the Heart and Soul Nebulas. The above image highlights a part of W5 spanning about 2,000 light years that is rich in star forming pillars. W5 lies about 6,500 light years away toward the constellation of Cassiopeia.

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[Ann]

Yes, those hot blue stars blast their own red hearts until they are empty, don't they?

But sometimes they pile up the remnants of their hearts along glowing red heart-outlines.

Only blue stars can build red hearts in space!

Ann

[DL MARTIN]

could it be that the hot outflowing gas compressing the cooler gas into gravitationally dense knots explains the variation in the appearance of the background noise?

[BennyH]

Hi.

This is a nice pic.
Reminds me of... christmas, somehow.

Anyway, we know a lot about how stars end their lifes, from the flashes and "fireworks" when it happens.
But with all these "star forming regions" I have read about here, I just wonder if anyone has actually seen a new star turned on, or just registered it through the last 100 years of astronomy.
Does anyone have a clue to what happens, or is it just guesswork?

Is it just turning on slowly, or lighting up like a match, or maybe a parade for the public with popcorn and cola, when God waves his magic wand?

Benny

[geckzilla]

Does anyone have a clue to what happens, or is it just guesswork?

Is it just turning on slowly, or lighting up like a match, or maybe a parade for the public with popcorn and cola, when God waves his magic wand?

When the dust curtain is drawn, things heat up behind them. It is a very hot affair with first a lot of friction and then eventually fusion.

[Ann]

Stars are born in dense, cold molecular clouds, which we may also describe as clouds of gas and dust. Some of these clouds start contracting due to their their own gravity, and when they have become very dense indeed the central mass of them can collapse into one or more so called proto-stars. Here is a picture of an embedded proto-star, still surrounded by much of the dense dusty cloud that it was born from.

Generally speaking, massive stars emerge from their natal clouds relatively quickly, because their fierce winds blow their birth clouds away. But the more light-weight a star is, the longer it takes for it to be born.

Ann

[BennyH]

Some of these clouds start contracting due to their their own gravity

Well... that rings a bell... so to say.

I had the idea that the atoms and molecules were just floating around, picking up more and more.
Thanks.

[MadMan]

When it first popped up on my screen, I was thinking "Pig Nebula", though I hadn't yet wondered why the pig was wearing a saddle.

[Chris Peterson]

But with all these "star forming regions" I have read about here, I just wonder if anyone has actually seen a new star turned on, or just registered it through the last 100 years of astronomy.
Does anyone have a clue to what happens, or is it just guesswork?

Stars don't "turn on", so there's no event that can be observed. Star formation is a process. Initially, gas (and a little dust) comes together under its mutual gravitational attraction, heating as it collapses. As the density rises, so does the temperature, and as the temperature rises, so does the brightness. This is the protostar phase, and these objects shine as brightly as stars, and outside their dusty surrounds are generally not distinguishable from stars. The only difference between a protostar and a normal star is that the protostar is heated by gravitational collapse, not fusion. Although it is as hot at its surface as fully formed stars, the protostar isn't hot enough inside to sustain fusion.

Once the protostar has accreted all the available gas and dust around it (typically blowing much away), it is considered a pre-main-sequence star. At this point it looks like other stars in most respects, but is still heated by gravitational collapse. After a short period in this phase, the interior becomes hot enough for hydrogen fusion to begin, and the star enters the main sequence. That might be the point we would call "turning on", but it doesn't change the appearance of the star at all.

[LocalColor]

Oh my, this image gave me goosebumps. Awe inspiring to be able to watch star formation in process. We are all "star stuff" as Dr. Sagan said.

[BillBixby]

But with all these "star forming regions" I have read about here, I just wonder if anyone has actually seen a new star turned on, or just registered it through the last 100 years of astronomy.
Does anyone have a clue to what happens, or is it just guesswork?

Stars don't "turn on", so there's no event that can be observed. Star formation is a process. Initially, gas (and a little dust) comes together under its mutual gravitational attraction, heating as it collapses. As the density rises, so does the temperature, and as the temperature rises, so does the brightness. This is the protostar phase, and these objects shine as brightly as stars, and outside their dusty surrounds are generally not distinguishable from stars. The only difference between a protostar and a normal star is that the protostar is heated by gravitational collapse, not fusion. Although it is as hot at its surface as fully formed stars, the protostar isn't hot enough inside to sustain fusion.

Once the protostar has accreted all the available gas and dust around it (typically blowing much away), it is considered a pre-main-sequence star. At this point it looks like other stars in most respects, but is still heated by gravitational collapse. After a short period in this phase, the interior becomes hot enough for hydrogen fusion to begin, and the star enters the main sequence. That might be the point we would call "turning on", but it doesn't change the appearance of the star at all.

Chris, your explanation was great! Years of study and investigation put into an explanation which seems clear and concise. Thank you.

[BennyH]

Stars don't "turn on", so there's no event that can be observed. Star formation is a process.

Wonderful explanation.

Thanks a lot Chris.

[DavidLeodis]

I would be grateful if anyone could please provide a link to the original image in the WISE website. I have looked through the gallery in the WISE website but if the original pre-processed image is there I did not find it. The first W5 in the explanation is a link to an image that looks like it could possibly have been used but the image data for that was acquired from the Spitzer Space Telescope, not WISE.

[Beyond]

Very unWISE of them, wasn't it?

[geckzilla]

I would be grateful if anyone could please provide a link to the original image in the WISE website. I have looked through the gallery in the WISE website but if the original pre-processed image is there I did not find it. The first W5 in the explanation is a link to an image that looks like it could possibly have been used but the image data for that was acquired from the Spitzer Space Telescope, not WISE.

It looks pretty similar to the Spitzer image. This is a screen capture from Aladin so this is not the highest quality image. In order to find original data you have to go through the IRSA website.

[DavidLeodis]

I would be grateful if anyone could please provide a link to the original image in the WISE website. I have looked through the gallery in the WISE website but if the original pre-processed image is there I did not find it. The first W5 in the explanation is a link to an image that looks like it could possibly have been used but the image data for that was acquired from the Spitzer Space Telescope, not WISE.

It looks pretty similar to the Spitzer image. This is a screen capture from Aladin so this is not the highest quality image. In order to find original data you have to go through the IRSA website.

wise_w5.jpg

Thanks for your help geckzilla . I've just tried searching the IRSA website for W5 but got hopelessly lost using the search function. My bad!

[geckzilla]

Thanks for your help geckzilla . I've just tried searching the IRSA website for W5 but got hopelessly lost using the search function. My bad!

W5 resolves to the correct coordinates using SIMBAD.

[Ron-Astro Pharmacist]

Sunday featured star formation within a molecular cloud and one of the links showed a simulation of a very dynamic-looking process possibly occurring only from gravitation.

Click to play embedded YouTube video.

This APOD has triggered star formation in which older star’s solar wind is supplying energy to compress gas and dust to induce star formation.

As discussed above there seems to be two mechanisms for star formation. These pillars never seem to be in an obvious state of twisting as in the simulation video. Do you suppose the pillars represent twisting over time; depositing gas and dust to form the pillars seen? Maybe the two ways are totally unrelated.

After a little searching I ran across this blurb but I don’t think I still “get it”.

http://earthsky.org/space/how-the-pilla ... re-created

Anyone offer a better explanation of pillar formation during star formation?