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4 votes
2 answers
118 views

Plage regions data

Plages are phenomena of stellar activity. Where can I find openly-accessible data of plage regions of the Sun with other parameters such as faculae region, magnetic field, etc?
Autodidact's user avatar
3 votes
2 answers
724 views

A question about the Fermi acceleration

In high school physics, we know that a charged particle cannot gain energy from a magnetic field. But, it seems that in the so-called Fermi acceleration, the particle is accelerated by the magnetic ...
S. Kohn's user avatar
  • 1,075
3 votes
1 answer
677 views

What's the difference between shock waves and acoustic waves?

What's the difference between shock waves and acoustic waves? I tried and searched around this subject, but I could not find any relative article about it. Please help me find a proper answer.
user236027's user avatar
2 votes
2 answers
205 views

Theoretical rocket engine based on plasma shock waves particle acceleration

Credits for the article - https://www.quantamagazine.org/cosmic-map-of-ultrahigh-energy-particles-points-to-long-hidden-treasures-20210427 Can this mechanism be used to speed up gas particles to ...
Corneliu Maftuleac's user avatar
2 votes
1 answer
88 views

What is the most efficient particle acceleration mechanism in space and astrophysical plasmas

My question is: What are the most efficient particle acceleration mechanisms in space and astrophysical plasmas: wave-particle interactions, collisionless shocks, or magnetic reconnection? Does it ...
Jokerp's user avatar
  • 490
2 votes
1 answer
212 views

Why does the transverse Alfven mode not undergo wave steepening and hence resulting in shock waves?

Initial Question: I am currently working through the second edition of Introduction to Plasma Physics by Donald A. Gurnett & A. Bhattacharjee In section 8.3.8 on page 304, they state that: .. on ...
D. Soul's user avatar
  • 724
2 votes
1 answer
64 views

Interaction of supersonic wind with static Inter-Stellar Medium (ISM)

Recently I was studying about the interaction of supersonic flow (wind) with a slowly flowing medium. In a paper by Dyson, Falle, and Perry 1980 MNRAS stated that when a supersonic wind impinged upon ...
Sayan's user avatar
  • 97
2 votes
1 answer
71 views

Derivation of average momentum change in diffusive shock acceleration

I am trying to figure out a specific step in the derivation of the power law spectrum for cosmic ray particles upon diffusive shock acceleration. I am working with Drury 1983 (pdf link) but I have ...
le chat's user avatar
  • 21
2 votes
1 answer
211 views

Particle acceleration at magnetized shocks by convective electric fields?

Let us assume we have a flow of charged particles in a quasi-neutral state (i.e., a plasma) convecting at some speed, $\mathbf{V}_{sw}$ = V$_{sw}$ $\hat{x}$, and the particles have species-dependent ...
honeste_vivere's user avatar
1 vote
1 answer
180 views

Wave drag in the interstellar medium

In Earth's atmosphere, an object moving at supersonic or near-supersonic speed experiences wave drag due to the formation of shock waves around the object's leading edge. At high speeds, wave drag is ...
Thorondor's user avatar
  • 4,110
1 vote
1 answer
459 views

The relative velocity of sound waves in Doppler effect

Let speed of sound in the medium be $v$ when the source is at rest w.r.t the medium. In the case of the observer moving towards the stationary source with a velocity of $u_1$, the speed of sound ...
Scar's user avatar
  • 72
1 vote
1 answer
178 views

Bulk viscosity in jump conditions for shock waves

One of the jump conditions for shock waves can be derived from the Navier-Stokes equation and it takes the form (see Shu, Gas dynamics, p.212) $\dfrac{d}{dx}\left(\rho u^2 + P - \frac{4}{3}\mu \frac{...
Max93's user avatar
  • 111