Starship Asterisk*

Looking Sideways from the Parker Solar Probe

Explanation: What's happening near the Sun? To help find out, NASA launched the robotic Parker Solar Probe (PSP) to investigate regions closer to the Sun than ever before. The PSP's looping orbit brings it nearer to the Sun each time around -- every few months. The featured time-lapse video shows the view looking sideways from behind PSP's Sun shield during its 16th approach to the Sun last year -- from well within the orbit of Mercury. The PSP's Wide Field Imager for Solar Probe (WISPR) cameras took the images over eleven days, but they are digitally compressed here into about one minute video. The waving of the solar corona is visible, as is a coronal mass ejection, with stars, planets, and even the central band of our Milky Way Galaxy streaming by in the background as the PSP orbits the Sun. PSP has found the solar neighborhood to be surprisingly complex and to include switchbacks -- times when the Sun's magnetic field briefly reverses itself.

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There is a cluster in the very beginning of the video (at 2 seconds). Could this cluster be M11? What do you think?


Ann

Some further Qs. In front of the passing view of the sky are random (?) streaks. Are these particles in the Corona, that we see further out but in front of the starry sky beyond? Or are they radiation particles, directly affecting the camera? And why are so many such streaks curved? A charged particle would curve in a strong magnetic field, but is the Sun's field so powerful where Parker is?
John

JohnD wrote: ↑Mon Feb 19, 2024 11:33 am Some further Qs. In front of the passing view of the sky are random (?) streaks. Are these particles in the Corona, that we see further out but in front of the starry sky beyond? Or are they radiation particles, directly affecting the camera? And why are so many such streaks curved? A charged particle would curve in a strong magnetic field, but is the Sun's field so powerful where Parker is?
John

They are certainly high energy particles interacting with the sensor. But we're not seeing the particles directly. Rather, we're seeing electrons they create inside individual pixels as they are moving through the bulk of the sensor material, where they undergo collisions and spawn secondary or tertiary particles and interact with other atoms. Which is presumably why the paths are so complex.

Chris Peterson wrote: ↑Mon Feb 19, 2024 2:25 pm

JohnD wrote: ↑Mon Feb 19, 2024 11:33 am Some further Qs. In front of the passing view of the sky are random (?) streaks. Are these particles in the Corona, that we see further out but in front of the starry sky beyond? Or are they radiation particles, directly affecting the camera? And why are so many such streaks curved? A charged particle would curve in a strong magnetic field, but is the Sun's field so powerful where Parker is?
John

They are certainly high energy particles interacting with the sensor. But we're not seeing the particles directly. Rather, we're seeing electrons they create inside individual pixels as they are moving through the bulk of the sensor material, where they undergo collisions and spawn secondary or tertiary particles and interact with other atoms. Which is presumably why the paths are so complex.

Thanks, as usual. I was disappointed that even the referenced source for the image makes no mention of the streaks.

Yes, thank you, Chris!

Then some of the secondary particles will be lighter (electrons?) and low energy, so more easily curved by weaker magnetic fields?
John

JohnD wrote: ↑Mon Feb 19, 2024 3:06 pm Yes, thank you, Chris!

Then some of the secondary particles will be lighter (electrons?) and low energy, so more easily curved by weaker magnetic fields?
John

The particles interact with atoms in the sensor, which can free up electrons (which is what fills up the pixels and gets read out as an image), and that interaction can alter the velocity of the particle (in the proper vector sense of "velocity"). There don't need to be any magnetic fields involved, although there may be. The velocity of charged particles is also affected by electric fields, of course.

Chris Peterson wrote: ↑Mon Feb 19, 2024 3:19 pm

JohnD wrote: ↑Mon Feb 19, 2024 3:06 pm Yes, thank you, Chris!

Then some of the secondary particles will be lighter (electrons?) and low energy, so more easily curved by weaker magnetic fields?
John

The particles interact with atoms in the sensor, which can free up electrons (which is what fills up the pixels and gets read out as an image), and that interaction can alter the velocity of the particle (in the proper vector sense of "velocity"). There don't need to be any magnetic fields involved, although there may be. The velocity of charged particles is also affected by electric fields, of course.

And I'd think that any curvature we see in the "paths" of the effect of such a solar particle on the sensor could not be due to curvature in solar magnetic field lines simply because those field lines would be essentially straight over such a short distance (and likely hundreds of miles!)

johnnydeep wrote: ↑Mon Feb 19, 2024 5:16 pm

Chris Peterson wrote: ↑Mon Feb 19, 2024 3:19 pm

JohnD wrote: ↑Mon Feb 19, 2024 3:06 pm Yes, thank you, Chris!

Then some of the secondary particles will be lighter (electrons?) and low energy, so more easily curved by weaker magnetic fields?
John

The particles interact with atoms in the sensor, which can free up electrons (which is what fills up the pixels and gets read out as an image), and that interaction can alter the velocity of the particle (in the proper vector sense of "velocity"). There don't need to be any magnetic fields involved, although there may be. The velocity of charged particles is also affected by electric fields, of course.

And I'd think that any curvature we see in the "paths" of the effect of such a solar particle on the sensor could not be due to curvature in solar magnetic field lines simply because those field lines would be essentially straight over such a short distance (and likely hundreds of miles!)

Absolutely. If magnetic fields are involved, they are local to the camera and probe.

Ann wrote: ↑Mon Feb 19, 2024 6:05 am There is a cluster in the very beginning of the video (at 2 seconds). Could this cluster be M11? What do you think?

APOD 19 February 2024 annotated.png

Cluster M11 in Scutum. Credit: Brucewaters

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Ann

Hi Ann

Actually, I wouldn't have had the time this evening. But it was just too much fun.
Answering your question in 2D doesn't work.
Working with spherical projections would be too time-consuming for me.

That's why the sequence shown is only backed up with a panorama of the Milky Way, just 4 fun.
bigggg: https://www.flickr.com/photos/185130090 ... 9/sizes/k/
jac berne (flickr)

Ann wrote: ↑Mon Feb 19, 2024 6:05 am There is a cluster in the very beginning of the video (at 2 seconds). Could this cluster be M11? What do you think?

APOD 19 February 2024 annotated.png

Cluster M11 in Scutum. Credit: Brucewaters

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Ann

The cluster is M44.
Being near the ecliptic, it was easy to find. On the left is from Stellarium, and on the right is a snip from the "featured time-lapse video" link
 

I've always admired that PSP can protect itself from the heat of the Sun, something many other robots cannot douno online

alter-ego wrote: ↑Tue Feb 20, 2024 12:46 am

Ann wrote: ↑Mon Feb 19, 2024 6:05 am There is a cluster in the very beginning of the video (at 2 seconds). Could this cluster be M11? What do you think?

APOD 19 February 2024 annotated.png

Cluster M11 in Scutum. Credit: Brucewaters

---

Ann

The cluster is M44.
Being near the ecliptic, it was easy to find. On the left is from Stellarium, and on the right is a snip from the "featured time-lapse video" link
 
Parker Probe View of M44.png

Thanks, alter-ego!

Ann