APOD: HH 47: A Young Star Jet Expands (2011 Sep 05)

[APOD Robot]

HH 47: A Young Star Jet Expands

Explanation: Stars remain where they are. Nebulas appear the same. Day after day. Year after year. Given the vast distances in astronomy, even fast moving objects will not appear to change their appearance in a human lifetime. Typically. A recent spectacular exception to this, however, is the supersonic jet in the star forming Herbig Haro 47. HH 47 is so close -- and the jets are moving so fast -- that images from the Hubble Space Telescope from 1994 to 2008 have been combined into a time-lapse movie that actually shows a powerful jet expanding. Visible above, jets of plasma extending over 10,000 times the Earth-Sun distance shoot out from a forming star at speeds in excess of 150 kilometers per second. Studying how these jets evolve gives clues not only to how the star in HH 47 is forming, but how stars like our Sun formed billions of years ago. HH 47 is located about 1,500 light years away toward the constellation of Sails of a Ship (Vela).

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[neufer]

Click to play embedded YouTube video.

[bystander]

Hubble Movies Show Supersonic Jets from Young Stars
http://asterisk.apod.com/viewtopic.php?t=25116

APOD Collection: Herbig-Haro Objects (HH)
http://asterisk.apod.com/viewtopic.php?t=25137

[tnzkka]

Okay, there is a jet, so there is gas to propagate (even sound)waves, but is it meaningful to speak of:

is the supersonic jet

? Please, enlighten me.

[Guest]

That's a nice thought - what is the speed of sound in a vacuum? Also, where is the star? From the motion, it looks like it must be very near the left edge.

[500pesos]

The star, I have no clue where it is, I don't see it either to be honest.

As for the "supersonic jet", the reference was to the speed of sound, as in, 'these jets move faster than the speed of sound', it should not be understood as meaning that a person floating in space close to them would hear the jets breaking the sound barrier; obviously without atmosphere one cannot have sound.

Also, the 'light year' is a distance measure.

[tnzkka]

@ Guest: as 500pesos states: there is no sound in vacuum.
@ 500pesos: speed of sound depends on the kind of gas, its temperature and a few more variables; I'm fully aware of that. My thoughts are based on the fact that Mach(speed)numbers vary with all these. So what is the use and extra information added by the statement: "the jet is supersonic"?
So "these jets move faster than the speed of sound" (perhaps meaning) in its own environment is a non-statement IMHO. ( sorry, it's difficult to state this properly in a foreing language)

[neufer]

speed of sound depends on the kind of gas, its temperature and a few more variables;

Primarily it depends on just the temperature & the molecular mass (which defines the random speed of the gas molecules themselves).

[b][color=#0000FF]Numerical Simulation of a Supersonic Gas Jet [Michael Norman National Center for Supercomputing Applications] The (simulated) jet enters through an inlet at left at six times the speed of sound (MAch 6) and with a density of one-tenth of the ambient density. The resulting interaction produces a turbulent cocoon surrounding the jet which is clearly seen in this simulation.[/color][/b]

---

The speed of sound in air at room temperature is ~ 300m/s because that is approximately the random speed of the air molecules. The speed of sound in these interstellar clouds is also ~ 300m/s because that is approximately the random speed of the cloud molecules.

My thoughts are based on the fact that Mach(speed)numbers vary with all these. So what is the use and extra information added by the statement: "the jet is supersonic"? So "these jets move faster than the speed of sound" (perhaps meaning) in its own environment is a non-statement IMHO.

Turbulent subsonic & supersonic gas jets are produced (or simulated) in laboratories all the time. Supersonic gas jets are unique in producing shock waves and those are precisely the features which are visible in today's APOD.

[orin stepanek]

That's a nice thought - what is the speed of sound in a vacuum? Also, where is the star? From the motion, it looks like it must be very near the left edge.

I take it that since the star is in the process of forming; therefore it is not yet formed!

[Boomer12k]

The outward expanding part just to the right of the circling blue area on the left.....looks like a STRUNG OUT DEAD CHICKEN GAG!!!!! OR A MODEL OF A KLINGON VESSEL Cool.


:------======= *

[Guest]

That's a nice thought - what is the speed of sound in a vacuum? Also, where is the star? From the motion, it looks like it must be very near the left edge.

I take it that since the star is in the process of forming; therefore it is not yet formed!

No, it (the newborn star) will be small, with almost all of the mass in it; what you see in the photo is outgoing jets of very small mass.

[drhr]

I see the 'left to right' distance appear to expand, but really I would say it's just a rotation, sans expansion. Looking at the matter on the right side is like focusing on one spoke, and you can't see the spokes ahead of it making the turn. A few more years maybe...

[Chris Peterson]

Okay, there is a jet, so there is gas to propagate (even sound)waves, but is it meaningful to speak of:

is the supersonic jet

? Please, enlighten me.

Yes. It means that the material making up the jet is moving faster than the speed that sound propagates in that medium. This has the consequence of producing shock fronts, which are a key component of the structure of the jet.

[tnzkka]

Thanks neufer

Turbulent subsonic & supersonic gas jets are produced (or simulated) in laboratories all the time. Supersonic gas jets are unique in producing shock waves and those are precisely the features which are visible in today's APOD.

& chris peterson

Yes. It means that the material making up the jet is moving faster than the speed that sound propagates in that medium. This has the consequence of producing shock fronts, which are a key component of the structure of the jet.

Something new learned today!!

[Psnarf]

Excweeze me? Did you say one hundred fifty kilometers per second?! Isn't that over a quarter million miles per hour? 335,540mph?! Less than an hour to get to the Moon?

Doesn't it take a rip-snorting electric and/or magnetic field to shape plasma into jets? Sew! is the source somewhere in that cloud on the left? Did it pop a cork as it rotates along the axis suggested by the jet? Such forces stagger the imagination.

[Chris Peterson]

Doesn't it take a rip-snorting electric and/or magnetic field to shape plasma into jets?

Yes... although we tend to view this in terms of our everyday environment. The energies involved are common enough in the Universe.

[neufer]

Did you say one hundred fifty kilometers per second?!
Isn't that over a quarter million miles per hour? 335,540mph?!
Less than an hour to get to the Moon?

Or, in other words, 0.05% the speed of light.

Doesn't it take a rip-snorting electric and/or magnetic field to shape plasma into jets? Sew! is the source somewhere in that cloud on the left? Did it pop a cork as it rotates along the axis suggested by the jet? Such forces stagger the imagination.

The exact mechanism can only be speculated upon but one can certainly envision a rapidly rotating plasma full of strong magnetic field lines that corkscrew out of both north & south poles thereby acting something like an Archimedes spiral pump.

[tom5867138]

WOW!!! i don't know why you guys are arguing over semantics, this is a great set of pictures... well done.

[islader2]

@ Boomer12K==There is no Klingon in this APOD. That shot is a picture of Wonder Woman's plane evanescing. Yuk! Yuk! And, NEUFER, I call such a visualization PERSECTIVE APPERCEPTION: a creative creation of my human mind devoid of misconstruction of reality to fool my brain into creating a tale {ipso facto} that my brain can store to be told to my fellow Homo sapiens sapiens around the campfire of our emerging humanity. It would give me a leg up on less creative "dudes." Thanx.

[Boomer12k]

@ Boomer12K==There is no Klingon in this APOD. That shot is a picture of Wonder Woman's plane evanescing. Yuk! Yuk! And, NEUFER, I call such a visualization PERSECTIVE APPERCEPTION: a creative creation of my human mind devoid of misconstruction of reality to fool my brain into creating a tale {ipso facto} that my brain can store to be told to my fellow Homo sapiens sapiens around the campfire of our emerging humanity. It would give me a leg up on less creative "dudes." Thanx.

Now do you see the shape of the broadside Klingon battle-cruiser? Just to the right of the swirling blue on the far left. Not the shape of the whole picture, just that part....

:-------======== *

[islader2]

@ Boomer12k==you got me! I see it now. Qapla'

[Beyond]

@ Boomer12k==you got me! I see it now. Qapla'

I thought that would be Ka-pla! But then, i have a hard enough time with inglish.

[JimH]

To my eye, the blue cloud on the left appears to be rotating around a vertical axis, with part of the cloud moving to the left, and part moving to the right. Does anyone know what this apparent rotation is? Maybe an illusion, the result of a parallax effect, or a true rotation (maybe around the star)?

[starman]

If you want to see a serious bit of protostar fun, try googling images for XZ Tauri. One set of images show matter ballooning out of it over the course of a relatively short timeframe. Herbig-Haro jets are collimated streams of ejecta from the poles of a rapidly-rotating young star. Whilst none are dead straight (because of the influences of nearby objects - the parent gas cloud may be clumpy for instance, or nearby stars, whether forming themselves or not) usually there is a tendency for a linear path to occur. Also, there is perspective to consider.