Starship Asterisk*

VictorBorun wrote: ↑Tue Mar 21, 2023 11:08 pm

johnnydeep wrote: ↑Tue Mar 21, 2023 8:31 pm

VictorBorun wrote: ↑Tue Mar 21, 2023 8:20 pm

But it's confusing to new-comers like me to watch the Crab Nebula as a beating heart, made to go through reversed motions with no jumps that the YouTube looped playing has.
Even after I had tried to relate to the year count in the top right corner, I was still struggling to see what currents are the radial expansion and what are curly-whirly when they were reversing their tides all the time

You, sir, are hardly a newcomer (though you are apparently humble)! And I didn't even notice the year in the top right corner until you mentioned it! Also, you may already know this, but if needed for closer examination of a video, you can click the gear icon in the lower right on the YouTube screen and change the playback speed to .5x or .25x to get a better look. And you can also speed it up, up to 2x normal speed, which is great for getting though boring videos, or slow talkers, in short order.

I was trying to say that this APOD's YouTube video, if looped like you advise, carried more clear message to me than the smooth oscillating motions of the original timelaps. So I am thankful to APOD for stripping the coolness and making the picture more educational

johnnydeep wrote: ↑Tue Mar 21, 2023 8:31 pm

VictorBorun wrote: ↑Tue Mar 21, 2023 8:20 pm

Detlef Hartmann wrote: ↑Mon Mar 20, 2023 10:29 pm

I have created a looped animated gif, which in the explanation is linked via time-lapse movie, the youtube movie has been created by the APOD team.

But it's confusing to new-comers like me to watch the Crab Nebula as a beating heart, made to go through reversed motions with no jumps that the YouTube looped playing has.
Even after I had tried to relate to the year count in the top right corner, I was still struggling to see what currents are the radial expansion and what are curly-whirly when they were reversing their tides all the time

You, sir, are hardly a newcomer (though you are apparently humble)! And I didn't even notice the year in the top right corner until you mentioned it! Also, you may already know this, but if needed for closer examination of a video, you can click the gear icon in the lower right on the YouTube screen and change the playback speed to .5x or .25x to get a better look. And you can also speed it up, up to 2x normal speed, which is great for getting though boring videos, or slow talkers, in short order.

VictorBorun wrote: ↑Tue Mar 21, 2023 8:20 pm

Detlef Hartmann wrote: ↑Mon Mar 20, 2023 10:29 pm

johnnydeep wrote: ↑Mon Mar 20, 2023 9:00 pm

It might help I suppose, but you can also just right-click in the video and select "Loop" from the context menu, and replay it! (It's a Youtube feature.)

I have created a looped animated gif, which in the explanation is linked via time-lapse movie, the youtube movie has been created by the APOD team.

But it's confusing to new-comers like me to watch the Crab Nebula as a beating heart, made to go through reversed motions with no jumps that the YouTube looped playing has.
Even after I had tried to relate to the year count in the top right corner, I was still struggling to see what currents are the radial expansion and what are curly-whirly when they were reversing their tides all the time

Detlef Hartmann wrote: ↑Mon Mar 20, 2023 10:29 pm

johnnydeep wrote: ↑Mon Mar 20, 2023 9:00 pm

NateWhilk wrote: ↑Mon Mar 20, 2023 8:52 pm This is a magnificent movie! I was just as impressed when Mr. Hartman released the 10-year version in 2017. (A humble suggestion: perhaps the next time APOD posts a short video like this, maybe make a single video that contains multiple copies of the source video, which would then be a rough simulation of a loop?)
...

It might help I suppose, but you can also just right-click in the video and select "Loop" from the context menu, and replay it! (It's a Youtube feature.)

I have created a looped animated gif, which in the explanation is linked via time-lapse movie, the youtube movie has been created by the APOD team.

Detlef Hartmann wrote: ↑Mon Mar 20, 2023 10:29 pm

johnnydeep wrote: ↑Mon Mar 20, 2023 9:00 pm

NateWhilk wrote: ↑Mon Mar 20, 2023 8:52 pm This is a magnificent movie! I was just as impressed when Mr. Hartman released the 10-year version in 2017. (A humble suggestion: perhaps the next time APOD posts a short video like this, maybe make a single video that contains multiple copies of the source video, which would then be a rough simulation of a loop?)
...

It might help I suppose, but you can also just right-click in the video and select "Loop" from the context menu, and replay it! (It's a Youtube feature.)

I have created a looped animated gif, which in the explanation is linked via time-lapse movie, the youtube movie has been created by the APOD team.

johnnydeep wrote: ↑Mon Mar 20, 2023 9:00 pm

NateWhilk wrote: ↑Mon Mar 20, 2023 8:52 pm This is a magnificent movie! I was just as impressed when Mr. Hartman released the 10-year version in 2017. (A humble suggestion: perhaps the next time APOD posts a short video like this, maybe make a single video that contains multiple copies of the source video, which would then be a rough simulation of a loop?)
...

It might help I suppose, but you can also just right-click in the video and select "Loop" from the context menu, and replay it! (It's a Youtube feature.)

johnnydeep wrote: ↑Mon Mar 20, 2023 9:00 pm

NateWhilk wrote: ↑Mon Mar 20, 2023 8:52 pm This is a magnificent movie! I was just as impressed when Mr. Hartman released the 10-year version in 2017. (A humble suggestion: perhaps the next time APOD posts a short video like this, maybe make a single video that contains multiple copies of the source video, which would then be a rough simulation of a loop?)
...

It might help I suppose, but you can also just right-click in the video and select "Loop" from the context menu, and replay it! (It's a Youtube feature.)

NateWhilk wrote: ↑Mon Mar 20, 2023 8:52 pm This is a magnificent movie! I was just as impressed when Mr. Hartman released the 10-year version in 2017. (A humble suggestion: perhaps the next time APOD posts a short video like this, maybe make a single video that contains multiple copies of the source video, which would then be a rough simulation of a loop?)
...

johnnydeep wrote: ↑Mon Mar 20, 2023 4:29 pm

Chris Peterson wrote: ↑Mon Mar 20, 2023 3:52 pm

johnnydeep wrote: ↑Mon Mar 20, 2023 3:35 pm So, over that 14 year period the Crab expanded about 0.046 ly, or about 1/20th of a lightyear.

There's a good deal of uncertainty about how far away M1 actually is, as well as uncertainty about its shape. But we do know its expansion rate along our line of sight very accurately because of spectroscopic measurements of the Doppler shift, yielding an axial speed of 1500 km/s. Because the radial expansion can actually be measured given the visible expansion, a distance can be estimated if we assume the radial expansion rate is the same as the axial one. In which case the distance works out to about 6300 ly, which is consistent with some of the results obtained by other methods.

Note that I used the 1000 km/s expansion rate from the APOD text. So if it's really 1500 km/s, it would have expanded 50% more over that 14 year animation.

What's the difference between your use of radial, axial, and line-of-sight expansion rates here? I can imagine the expansion rate being different along many different directions from the nebula! Is axial the same as line-of-sight here? And is radial simply the expansion within the plane perpendicular to that line that we see visual evidence of in this animation?

Chris Peterson wrote: ↑Mon Mar 20, 2023 3:52 pm

johnnydeep wrote: ↑Mon Mar 20, 2023 3:35 pm So, over that 14 year period the Crab expanded about 0.046 ly, or about 1/20th of a lightyear.

There's a good deal of uncertainty about how far away M1 actually is, as well as uncertainty about its shape. But we do know its expansion rate along our line of sight very accurately because of spectroscopic measurements of the Doppler shift, yielding an axial speed of 1500 km/s. Because the radial expansion can actually be measured given the visible expansion, a distance can be estimated if we assume the radial expansion rate is the same as the axial one. In which case the distance works out to about 6300 ly, which is consistent with some of the results obtained by other methods.

johnnydeep wrote: ↑Mon Mar 20, 2023 3:35 pm So, over that 14 year period the Crab expanded about 0.046 ly, or about 1/20th of a lightyear.

Ann wrote: ↑Mon Mar 20, 2023 6:00 am ...

I agree with today's caption that this time-lapse video is indeed stunning.

Bundle of energy: with its strong magnetic field (white lines), the Crab Pulsar spins around itself nearly 30 times per second injecting energetic electrons in the space region around it. The green and blue shaded regions depict different particle acceleration zones from where the detected photons could originate. The green zone lies in the vicinity of the pulsar's magnetosphere, whereas the blue zone could be as far as 100,000 km away from the pulsar. © Patricia Carcelén Marco

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Max Planck Gesellschaft wrote:

The Crab Nebula is the remnant of a supernova explosion that was observed on Earth in the year 1054. The neutron star has a diameter of just around ten kilometers and rotates around its own axis approximately 30 times per second. Thus, it emits light pulses like a lighthouse, and these pulses stretch across the entire electromagnetic spectrum — from long radio waves to visible light and beyond, to the short waves of energetic gamma rays.

Ann

Max Planck Gesellschaft wrote:

The Crab Nebula is the remnant of a supernova explosion that was observed on Earth in the year 1054. The neutron star has a diameter of just around ten kilometers and rotates around its own axis approximately 30 times per second. Thus, it emits light pulses like a lighthouse, and these pulses stretch across the entire electromagnetic spectrum — from long radio waves to visible light and beyond, to the short waves of energetic gamma rays.