APOD: Henize 70: A Superbubble in the LMC (2019 Feb 04)

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APOD: Henize 70: A Superbubble in the LMC (2019 Feb 04)

Post by APOD Robot » Mon Feb 04, 2019 5:12 am

Image Henize 70: A Superbubble in the LMC

Explanation: Massive stars profoundly affect their galactic environments. Churning and mixing interstellar clouds of gas and dust, stars -- most notably those upwards of tens of times the mass of our Sun -- leave their mark on the compositions and locations of future generations of stars. Dramatic evidence of this is illustrated in our neighboring galaxy, the Large Magellanic Cloud (LMC), by the featured nebula, Henize 70 (also known as N70 and DEM301). Henize 70 is actually a luminous superbubble of interstellar gas about 300 light-years in diameter, blown by winds from hot, massive stars and supernova explosions, with its interior filled with tenuous hot and expanding gas. Because superbubbles can expand through an entire galaxy, they offer humanity a chance to explore the connection between the lifecycles of stars and the evolution of galaxies.

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Re: APOD: Henize 70: A Superbubble in the LMC (2019 Feb 04)

Post by Boomer12k » Mon Feb 04, 2019 6:55 am

Great image... great object....we exist inside our own..."Local bubble"...
Um...Ok....now I am wondering if anyone in the LMC is taking a picture of OUR bubble....hmmmm.....

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Re: APOD: Henize 70: A Superbubble in the LMC (2019 Feb 04)

Post by NCTom » Mon Feb 04, 2019 12:36 pm

How would we on earth recognize our system was passing through such a superbubble/shell? None of the descriptions I read discussed the density/thickness of the shell itself, only its expanding dimensions.

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Re: APOD: Henize 70: A Superbubble in the LMC (2019 Feb 04)

Post by Chris Peterson » Mon Feb 04, 2019 2:06 pm

NCTom wrote:
Mon Feb 04, 2019 12:36 pm
How would we on earth recognize our system was passing through such a superbubble/shell? None of the descriptions I read discussed the density/thickness of the shell itself, only its expanding dimensions.
It would raise the background brightness of the sky, and instrumentally, we'd observe a number of emission lines in that background, as well as evidence of structure.

(Indeed, we are currently inside a bubble which is slightly less dense than the surrounding interstellar medium, and is approximately the same size as the bubble in this APOD. Our local bubble is mapped using radio and x-ray emissions.)
Chris

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Re: APOD: Henize 70: A Superbubble in the LMC (2019 Feb 04)

Post by neufer » Mon Feb 04, 2019 5:34 pm

Chris Peterson wrote:
Mon Feb 04, 2019 2:06 pm
NCTom wrote:
Mon Feb 04, 2019 12:36 pm

How would we on earth recognize our system was passing through such a superbubble/shell? None of the descriptions I read discussed the density/thickness of the shell itself, only its expanding dimensions.
It would raise the background brightness of the sky, and instrumentally, we'd observe a number of emission lines in that background, as well as evidence of structure. (Indeed, we are currently inside a bubble which is slightly less dense than the surrounding interstellar medium, and is approximately the same size as the bubble in this APOD. Our local bubble is mapped using radio and x-ray emissions.)
https://en.wikipedia.org/wiki/Superbubble wrote:
<<A superbubble or supershell is a cavity which is hundreds of light years across and is populated with hot (106 K) gas atoms, less dense than the surrounding interstellar medium, blown against that medium and carved out by multiple supernovae and stellar winds. The winds, passage and gravity of newly born stars strip superbubbles of any other dust or gas. The Solar System lies near the center of an old superbubble, known as the Local Bubble, whose boundaries can be traced by a sudden rise in dust extinction of exterior stars at distances greater than a few hundred light years.

Click to play embedded YouTube video.
The superburghol HENIZE 70, a.k.a. N70 or DEM301, in the LMCloud
The most massive stars, with masses ranging from 8 to ~100 solar masses and spectral types of O and early B, are usually found in groups called OB associations. Massive O stars have strong stellar winds, and most of these stars explode as supernovae at the end of their lives. The strongest stellar winds release kinetic energy of 1051 ergs over the lifetime of a star, which is equivalent to a supernova explosion. These winds can form stellar wind bubbles dozens of light years across. Inside OB associations, the stars are close enough that their wind bubbles merge, forming a giant bubble called a superbubble. When stars die, supernova explosions, similarly, drive blast waves that can reach even larger sizes, with expansion velocities up to several hundred km/s. Stars in OB associations are not gravitationally bound, but they drift apart at small speeds (of around 20 km/s), and they exhaust their fuel rapidly (after a few millions of years). As a result, most of their supernova explosions occur within the cavity formed by the stellar wind bubbles. These explosions never form a visible supernova remnant, but instead expend their energy in the hot interior as sound waves. Both stellar winds and stellar explosions thus power the expansion of the superbubble in the interstellar medium.

The interstellar gas swept up by superbubbles generally cools, forming a dense shell around the cavity. These shells were first observed in line emission at 21 centimeters from hydrogen, leading to the formulation of the theory of superbubble formation. They are also observed in X-ray emission from their hot interiors, in optical line emission from their ionized shells, and in infrared continuum emission from dust swept up in their shells. X-ray and visible emission are typically observed from younger superbubbles, while older, larger objects seen in 21 centimeters may even result from multiple superbubbles combining, and so are sometimes distinguished by calling them supershells.>>
https://en.wikipedia.org/wiki/Local_Bubble wrote: <<The Local Bubble, or Local Cavity, is a relative cavity in the interstellar medium (ISM) of the Orion Arm in the Milky Way. It contains among others, the Local Interstellar Cloud, which contains the Solar System, and the G-Cloud. It is at least 300 light years across and is defined by its neutral-hydrogen density of about 0.05 atoms/cm3, or approximately one tenth of the average for the ISM in the Milky Way, and one sixth that of the Local Interstellar Cloud. The Solar System has been traveling through the region currently occupied by the Local Bubble for the last five to ten million years.

The exceptionally sparse matter, namely gas, of the Local Bubble is the result of supernovae that exploded within the past ten to twenty million years and remains in an excited state, emitting in the X-ray band. It has been suggested that multiple supernovae in subgroup B1 of the Pleiades moving group were more likely responsible, becoming a remnant supershell.

Launched in February 2003 and active until April 2008, a small space observatory called Cosmic Hot Interstellar Plasma Spectrometer (CHIPS or CHIPSat) examined the hot gas within the Local Bubble. The Local Bubble was also the region of interest for the Extreme Ultraviolet Explorer mission (1992–2001), which examined hot EUV sources within the bubble. Sources beyond the edge of the bubble were identified, but attenuated by the denser interstellar medium.>>
Art Neuendorffer

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Re: APOD: Henize 70: A Superbubble in the LMC (2019 Feb 04)

Post by MarkBour » Mon Feb 04, 2019 10:57 pm

neufer wrote:
Mon Feb 04, 2019 5:34 pm
...
https://www.youtube.com/watch?v=8fIfPKpY7HQ
The superburghol HENIZE 70, a.k.a. N70 or DEM301, in the LMCloud
...
Thanks for this info, Art. The Youtube link you included appears to be Andy Warhol eating a burger. Is that what you intended, or is it something wrong with my reference-following? (Or, perhaps both.)
Mark Goldfain

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Re: APOD: Henize 70: A Superbubble in the LMC (2019 Feb 04)

Post by orin stepanek » Mon Feb 04, 2019 11:03 pm

I like today's APOD! 8-) :thumb_up: :thumb_up:
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Re: APOD: Henize 70: A Superbubble in the LMC (2019 Feb 04)

Post by neufer » Mon Feb 04, 2019 11:16 pm

MarkBour wrote:
Mon Feb 04, 2019 10:57 pm
neufer wrote:
Mon Feb 04, 2019 5:34 pm
...
https://www.youtube.com/watch?v=8fIfPKpY7HQ
The superburghol HENIZE 70, a.k.a. N70 or DEM301, in the LMCloud
...
Thanks for this info, Art. The Youtube link you included appears to be Andy Warhol eating a burger. Is that what you intended, or is it something wrong with my reference-following? (Or, perhaps both.)
  • APOD's red Henize 70 Superbubble blob reminded me of
    last night's red Heinz 57 Superbowl blob generated by Andy Warhol.

    (And no...I not really "well.")
Art Neuendorffer

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Re: APOD: Henize 70: A Superbubble in the LMC (2019 Feb 04)

Post by MarkBour » Wed Feb 06, 2019 9:51 am

neufer wrote:
Mon Feb 04, 2019 11:16 pm
  • APOD's red Henize 70 Superbubble blob reminded me of
    last night's red Heinz 57 Superbowl blob generated by Andy Warhol.
Ah. Sorry to make you explain it. Maybe I should have watched that Superbowl. ... Nah.
Mark Goldfain