Reverse Shock Wave Racing Inward at 1000 Times the Speed of Sound

November 26, 2013


Reverse Shock Wave Racing Inward at 1000 Times the Speed of Sound

A photograph of the Tycho supernova remnant taken by the Chandra X-ray Observatory. Low-energy X-rays (red) in the image show expanding debris from the supernova explosion and high energy X-rays (blue) show the blast wave, a shell of extremely energetic electrons. X-ray: NASA/CXC/Rutgers/K. Eriksen et al.; Optical (starry background): DSS

Researchers from the Harvard-Smithsonian Center for Astrophysics have discovered that a reverse shock wave racing inward at 1000 times the speed of sound is heating the Tycho supernova remnant and causing it to emit X-ray light.

Cambridge, Massachusetts – When a star explodes as a supernova, it shines brightly for a few weeks or months before fading away. Yet the material blasted outward from the explosion still glows hundreds or thousands of years later, forming a picturesque supernova remnant. What powers such long-lived brilliance?

In the case of Tycho’s supernova remnant, astronomers have discovered that a reverse shock wave racing inward at Mach 1000 (1000 times the speed of sound) is heating the remnant and causing it to emit X-ray light.

“We wouldn’t be able to study ancient supernova remnants without a reverse shock to light them up,” says Hiroya Yamaguchi, who conducted this research at the Harvard-Smithsonian Center for Astrophysics (CfA).

Tycho’s supernova was witnessed by astronomer Tycho Brahe in 1572. The appearance of this “new star” stunned those who thought the heavens were constant and unchanging. At its brightest, the supernova rivaled Venus before fading from sight a year later.

Modern astronomers know that the event Tycho and others observed was a Type Ia supernova, caused by the explosion of a white dwarf star. The explosion spewed elements like silicon and iron into space at speeds of more than 11 million miles per hour (5,000 km/s).

When that ejecta rammed into surrounding interstellar gas, it created a shock wave – the equivalent of a cosmic “sonic boom.” That shock wave continues to move outward today at about Mach 300. The interaction also created a violent “backwash” – a reverse shock wave that speeds inward at Mach 1000.

“It’s like the wave of brake lights that marches up a line of traffic after a fender-bender on a busy highway,” explains CfA co-author Randall Smith.

The reverse shock wave heats gases inside the supernova remnant and causes them to fluoresce. The process is similar to what lights household fluorescent bulbs, except that the supernova remnant glows in X-rays rather than visible light. The reverse shock wave is what allows us to see supernova remnants and study them, hundreds of years after the supernova occurred.

“Thanks to the reverse shock, Tycho’s supernova keeps on giving,” says Smith.

The team studied the X-ray spectrum of Tycho’s supernova remnant with the Suzaku spacecraft. They found that electrons crossing the reverse shock wave are rapidly heated by a still-uncertain process. Their observations represent the first clear evidence for such efficient, “collisionless” electron heating at the reverse shock of Tycho’s supernova remnant.

The team plans to look for evidence of similar reverse shock waves in other young supernova remnants.

These results have been accepted for publication in The Astrophysical Journal.

Headquartered in Cambridge, Massachusetts, the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

Publication: Accepted for publication in The Astrophysical Journal

PDF Copy of the Study: New Evidence for Efficient Collisionless Heating of Electrons at the Reverse Shock of a Young Supernova Remnant

Source: Harvard-Smithsonian Center for Astrophysics

Image: X-ray: NASA/CXC/Rutgers/K. Eriksen et al.; Optical (starry background): DSS

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10 Responses to “Reverse Shock Wave Racing Inward at 1000 Times the Speed of Sound”

  1. James ( JIM) Oss Says:

    When it all comes together, will a black hole be formed, or is there already one there?


    • apex predator Says:

      nope nor is it likely it ever will white dwarf is a small star
      in the end whats left could be a dim brown dwarf maybe tops neutron star seems likely
      Once they go black hole (super large stars) its game over
      Till as steven hawkins suggested it peters out (That only being the case should it not have things to feed on for a very very longtime


  2. robert stewart Says:

    did anyone ever wonder if space wasnt completely empty? like if it was just super light molecules that made it SEEM like a vaccum?


    • nelson summers Says:

      If there were super light molecules they would be able to measure them some how Im sure Not unless they are so light that no instrument known to man can measure them It could be possible We are not the smartest people in the universe and Im sure if you believe that we are then you are fooling yourself.


    • Bob Wise Says:

      Hey Robert Stewart!

      You have no idea how correct you really are! Check out Nassim Harramein “Theories!”

      btw…Am I the only one that noticed they used the “speed of sound” as a measuring stick? wtf? “speed of sound”…IN SPACE???

      “NO WAY!!!”

      unless…”our” scientists have been misleading us all this time???

      Naw! “conspiracy thinking…huh!”


    • apex predator Says:

      well it is empty for the most part Lets take this keyboard Im tapping on Its not my atoms touching its atoms Its the electric charge That pushes the key down Their is so much room between atoms without the eletric charge my finger would pass the key like a ghost passing into a wall


    • Peter Jackson FRAS Says:

      We well know space is certainly NOT completely empty. The ‘Quantum Vacuum’ (QV) description (ISM and IGM) is now joined by the Higg’s field. Fermions and ions form plasma, the most abundant form of matter and ‘dark’ in EM profile terms as it has a refractive index of 1.
      I rather think the analysis in this paper uses different assumptions, as do most philosophers and (still) many theoretical physicists! i.e. we may well find this ‘inward wind’ is not required after all.

      Good question. if the Crab nebula core is anything to go by then one will form/re-form. (Google the NASA HST shots). The Jet there is already emitting GRB’s.


  3. Pat Says:

    Wait, what? a HEATED ELECTRONS?? How is this even possible?? Heat is motion- the motion of molecules right? And electrons move at nearly c. So how do you heat them up any more?? And how can a fundamental particle have heat?


  4. Madanagopal.V.C Says:

    Hello! Electrons are heated up means only that they are energized and no actual heating is done. You know that when K shell electrons or the innermost orbit electrons are pulled up to higher orbits they emit X-rays, and at different levels the electrons emit U-V,and visible rays. Infra-red or heat waves are emitted when molecules are perturbed as a whole and when atoms are perturbed , you get visible and X-rays. If the nucleus itself is perturbed you do get Gamma rays and also electrons as Beta rays. Heat is definitely a bye-product meaning that it stands for lesser energized quanta. Consider Atomic Explosion where you meddle with only the nucleus, but it leashes extremely high heat.Hello! one more point to add. Who said that inter-stellar space is completely vacuum? It is compressed with highly energetic Dark Energy and Dark Matter, which is capable of gravitational deflecting even cosmic gamma rays to heat up anything.
    Thank YOu.


  5. w.basham Says:

    I wonder at the socially redeeming values of these learned speculations; what ever difference can come of these ¿actions? better yet who will go to personally observe firsthand this phenomena? And to what constructive ends are perceived? Other than to give many erstwhile astrophysicists something to do? So beit! Suppose there must be an underlying reason for all this foofarall!


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