Starship Asterisk*

johnnydeep wrote: ↑Sun Aug 06, 2023 3:16 pm For those wondering, this is where this fragment is situated in the larger nebula:

From https://www.eso.org/public/images/eso1308a/

Credit: ESO, Radio: NRAO/AUI/NSF/GBT/VLA/Dyer, Maddalena & Cornwell, X-ray: Chandra X-ray Observatory; NASA/CXC/Rutgers/G. Cassam-Chenaï, J. Hughes et al., Visible light: 0.9-metre Curtis Schmidt optical telescope; NOAO/AURA/NSF/CTIO/Middlebury College/F. Winkler and Digitized Sky Survey.

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Very detailed new observations with ESO’s Very Large Telescope (VLT) of the remains of a thousand-year-old supernova have revealed clues to the origins of cosmic rays.

The image on the left shows the entire SN 1006 supernova remnant, as seen in radio (red), X-ray (blue) and visible light (yellow)███. The second panel, corresponding to the small square region marked at the left, is a NASA/ESA Hubble Space Telescope close up view of the remarkably narrow region of the shock front, where the material from the supernova is colliding with interstellar medium.

De58te wrote: ↑Sun Aug 06, 2023 8:46 am Cool. A shock wave that actually looks like a wave. I wonder do we know which direction it is moving? Is it moving from right to left or vice versa like a wave on the ocean, or is it moving in one mass from top to bottom or vice versa.

johnnydeep wrote: ↑Sun Aug 06, 2023 3:16 pm For those wondering, this is where this fragment is situated in the larger nebula:

From https://www.eso.org/public/images/eso1308a/

Credit: ESO, Radio: NRAO/AUI/NSF/GBT/VLA/Dyer, Maddalena & Cornwell, X-ray: Chandra X-ray Observatory; NASA/CXC/Rutgers/G. Cassam-Chenaï, J. Hughes et al., Visible light: 0.9-metre Curtis Schmidt optical telescope; NOAO/AURA/NSF/CTIO/Middlebury College/F. Winkler and Digitized Sky Survey.

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Very detailed new observations with ESO’s Very Large Telescope (VLT) of the remains of a thousand-year-old supernova have revealed clues to the origins of cosmic rays.

The image on the left shows the entire SN 1006 supernova remnant, as seen in radio (red), X-ray (blue) and visible light (yellow). The second panel, corresponding to the small square region marked at the left, is a NASA/ESA Hubble Space Telescope close up view of the remarkably narrow region of the shock front, where the material from the supernova is colliding with interstellar medium. The third panel shows how the integral field unit of the VIMOS instrument splits up the image into many small regions, the light from each of which is spread out into a spectrum of its component colours. When these spectra are analysed, maps of the properties of the underlying object can be derived. The example shown here at the right is a map of one property of the gas (the width a spectral line), which is surprisingly variable, and implies, along with other indicators, the presence of very high-speed protons.

Ann wrote: ↑Sun Aug 06, 2023 3:38 pm

Chris Peterson wrote: ↑Sun Aug 06, 2023 3:07 pm

Ann wrote: ↑Sun Aug 06, 2023 2:55 pm

Good point, Chris. Thanks.

Doesn't explain the lack of cyan, though. But maybe, for some reason, there is no OIII here.

Ann

The 606W filter is a conventional red filter. The 505W filter is a conventional green filter. Neither will produce the colors you've represented given a white light source. While the green filter certainly captures [O III], it also captures a lot around it. Green filters do a pretty good job imaging [O III] in the absence of continuum light sources mixed with it, but if you have a lot of white light, not so much. So the question here is whether there is little oxygen, or whether its color is just being washed out. To know for sure, you'd need some narrowband data. But it's possible that a lot more could be learned from looking at the individual channels. As I've noted before, color images like this aren't very useful scientifically. They just throw away or hide too much information.

Agreed, Chris. I remember the old Hubble Heritage images. They always showed you the individual filter images as well as the finished color image. Sometimes they would even show you various versions of suggested color images derived from the individual filter images. That was just so interesting!

NGC 4650A. Credits: Hubble Heritage Team (AURA/STScI/NASA)

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I'm pretty sure that the old Hubble Heritage site showed us two other "color versions" of NGC 4650A, before they settled on this one. I wish they would do things like that now, too.

Ann

Chris Peterson wrote: ↑Sun Aug 06, 2023 3:07 pm

Ann wrote: ↑Sun Aug 06, 2023 2:55 pm

Chris Peterson wrote: ↑Sun Aug 06, 2023 2:10 pm

Got to be careful with such comparisons, however. The remnant in today's APOD is less than a tenth of the age of the Vela remnants. It is hardly surprising that a recent SN would have finer structure surrounding it. Material is denser, speeds are higher, and the time for stuff to diffuse much less.

Good point, Chris. Thanks.

Doesn't explain the lack of cyan, though. But maybe, for some reason, there is no OIII here.

Ann

The 606W filter is a conventional red filter. The 505W filter is a conventional green filter. Neither will produce the colors you've represented given a white light source. While the green filter certainly captures [O III], it also captures a lot around it. Green filters do a pretty good job imaging [O III] in the absence of continuum light sources mixed with it, but if you have a lot of white light, not so much. So the question here is whether there is little oxygen, or whether its color is just being washed out. To know for sure, you'd need some narrowband data. But it's possible that a lot more could be learned from looking at the individual channels. As I've noted before, color images like this aren't very useful scientifically. They just throw away or hide too much information.

Very detailed new observations with ESO’s Very Large Telescope (VLT) of the remains of a thousand-year-old supernova have revealed clues to the origins of cosmic rays.

The image on the left shows the entire SN 1006 supernova remnant, as seen in radio (red), X-ray (blue) and visible light (yellow). The second panel, corresponding to the small square region marked at the left, is a NASA/ESA Hubble Space Telescope close up view of the remarkably narrow region of the shock front, where the material from the supernova is colliding with interstellar medium. The third panel shows how the integral field unit of the VIMOS instrument splits up the image into many small regions, the light from each of which is spread out into a spectrum of its component colours. When these spectra are analysed, maps of the properties of the underlying object can be derived. The example shown here at the right is a map of one property of the gas (the width a spectral line), which is surprisingly variable, and implies, along with other indicators, the presence of very high-speed protons.

Ann wrote: ↑Sun Aug 06, 2023 2:55 pm

Chris Peterson wrote: ↑Sun Aug 06, 2023 2:10 pm

Ann wrote: ↑Sun Aug 06, 2023 6:35 am I'm a bit surprised at the color of shock front in the APOD, but I'm more surprised at the shock front's razor-sharp edges and perfectly uniform width.

Let's compare the APOD with two pictures of the Vela supernova remnant, one wide-angle picture of much of the supernova remnant, and one closeup of the part of the Vela supernova remnant known as the Pencil Nebula:

Got to be careful with such comparisons, however. The remnant in today's APOD is less than a tenth of the age of the Vela remnants. It is hardly surprising that a recent SN would have finer structure surrounding it. Material is denser, speeds are higher, and the time for stuff to diffuse much less.

Good point, Chris. Thanks.

Doesn't explain the lack of cyan, though. But maybe, for some reason, there is no OIII here.

Ann

Chris Peterson wrote: ↑Sun Aug 06, 2023 2:10 pm

Ann wrote: ↑Sun Aug 06, 2023 6:35 am I'm a bit surprised at the color of shock front in the APOD, but I'm more surprised at the shock front's razor-sharp edges and perfectly uniform width.

Let's compare the APOD with two pictures of the Vela supernova remnant, one wide-angle picture of much of the supernova remnant, and one closeup of the part of the Vela supernova remnant known as the Pencil Nebula:

Got to be careful with such comparisons, however. The remnant in today's APOD is less than a tenth of the age of the Vela remnants. It is hardly surprising that a recent SN would have finer structure surrounding it. Material is denser, speeds are higher, and the time for stuff to diffuse much less.

Ann wrote: ↑Sun Aug 06, 2023 6:35 am I'm a bit surprised at the color of shock front in the APOD, but I'm more surprised at the shock front's razor-sharp edges and perfectly uniform width.

Let's compare the APOD with two pictures of the Vela supernova remnant, one wide-angle picture of much of the supernova remnant, and one closeup of the part of the Vela supernova remnant known as the Pencil Nebula:

APOD Robot wrote:

What created this unusual space ribbon? The answer: one of the most violent explosions ever witnessed by ancient humans. Back in the year 1006 AD, light reached Earth from a stellar explosion in the constellation of the Wolf (Lupus), creating a "guest star" in the sky that appeared brighter than Venus and lasted for over two years...

Pictured here is a small part of that expanding supernova remnant dominated by a thin and outwardly moving shock front that heats and ionizes surrounding ambient gas.

Hubblesite wrote:

This image combines several exposures in both ACS and WFPC2. The ACS images were exposed through a filter transmitting the light of hydrogen, and the WFPC2 images were made through three filters transmitting wide bands of color in the red and near infrared, yellow- green, and blue portions of the spectrum. In the color composite, the ACS image is shown in red, the WFPC2 red/IR filter images are shown in red-orange, yellow-green filter images in green, and blue filter images in blue-violet. Blue: F439W (B) Green: F555W (V) (Green=F555W) Red: F658 N (H-alpha+[N II]) + F814W (I)