Runaway stars leave infrared waves in space

January 5, 2016
Bow shocks thought to mark the paths of massive, speeding stars are highlighted in these images from NASA's Spitzer Space Telescope and Wide-field Infrared Survey Explorer, or WISE. Credit: NASA/JPL-Caltech/University of Wyoming

Astronomers are finding dozens of the fastest stars in our galaxy with the help of images from NASA's Spitzer Space Telescope and Wide-field Infrared Survey Explorer, or WISE.

When some speedy, massive plow through space, they can cause material to stack up in front of them in the same way that water piles up ahead of a ship. Called bow shocks, these dramatic, arc-shaped features in space are leading researchers to uncover massive, so-called runaway stars.

"Some stars get the boot when their companion star explodes in a supernova, and others can get kicked out of crowded star clusters," said astronomer William Chick from the University of Wyoming in Laramie, who presented his team's new results at the American Astronomical Society meeting in Kissimmee, Florida. "The gravitational boost increases a star's speed relative to other stars."

Our own sun is strolling through our Milky Way galaxy at a moderate pace. It is not clear whether our sun creates a bow shock. By comparison, a massive star with a stunning bow shock, called Zeta Ophiuchi (or Zeta Oph), is traveling around the galaxy faster than our sun, at 54,000 mph (24 kilometers per second) relative to its surroundings. Zeta Oph's giant bow shock can be seen in this image from the WISE mission:

The blue star near the center of this image is Zeta Ophiuchi. When seen in visible light it appears as a relatively dim red star surrounded by other dim stars and no dust. However, in this infrared image taken with NASA's Wide-field Infrared Survey Explorer, or WISE, a completely different view emerges. Zeta Ophiuchi is actually a very massive, hot, bright blue star plowing its way through a large cloud of interstellar dust and gas. Astronomers theorize that this stellar juggernaut was likely once part of a binary star system with an even more massive partner. It's believed that when the partner exploded as a supernova, blasting away most of its mass, Zeta Ophiuchi was suddenly freed from its partner's pull and shot away like a bullet moving 24 kilometers per second (54,000 miles per hour). Zeta Ophiuchi is about 20 times more massive and 65,000 times more luminous than the sun. If it weren't surrounded by so much dust, it would be one of the brightest stars in the sky and appear blue to the eye. Like all stars with this kind of extreme mass and power, it subscribes to the 'live fast, die young' motto. It's already about halfway through its very short 8-million-year lifespan. In comparison, the sun is roughly halfway through its 10-billion-year lifespan. While the sun will eventually become a quiet white dwarf, Zeta Ophiuchi, like its ex-partner, will ultimately die in a massive explosion called a supernova. Perhaps the most interesting features in this image are related to the interstellar gas and dust that surrounds Zeta Ophiuchi. Off to the sides of the image and in the background are relatively calm clouds of dust, appearing green and wispy, slightly reminiscent of the northern lights. Near Zeta Ophiuchi, these clouds look quite different. The cloud in all directions around the star is brighter and redder, because the extreme amounts of ultraviolet radiation emitted by the star are heating the cloud, causing it to glow more brightly in the infrared than usual. Even more striking, however, is the bright yellow curved feature directly above Zeta Ophiuchi. This is a magnificent example of a bow shock. In this image, the runaway star is flying from the lower right towards the upper left. As it does so, its very powerful stellar wind is pushing the gas and dust out of its way (the stellar wind extends far beyond the visible portion of the star, creating an invisible 'bubble' all around it). And directly in front of the star's path the wind is compressing the gas together so much that it is glowing extremely brightly (in the infrared), creating a bow shock. It is akin to the effect you might see when a boat pushes a wave in front it as it moves through the water. This feature is completely hidden in visible light. Infrared images like this one from WISE shed an entirely new light on the region. The colors used in this image represent specific wavelengths of infrared light. Blue and cyan (blue-green) represent light emitted at wavelengths of 3.4 and 4.6 microns, which is predominantly from stars. Green and red represent light from 12 and 22 microns, respectively, which is mostly emitted by dust. Credit: NASA/JPL-Caltech/UCLA

Both the speed of stars moving through space and their mass contribute to the size and shapes of bow shocks. The more massive a star, the more material it sheds in high-speed winds. Zeta Oph, which is about 20 times as massive as our sun, has supersonic winds that slam into the material in front of it.

The result is a pile-up of material that glows. The arc-shaped material heats up and shines with . That infrared light is assigned the color red in the many pictures of bow shocks captured by Spitzer and WISE.

Chick and his team turned to archival infrared data from Spitzer and WISE to identify new bow shocks, including more distant ones that are harder to find. Their initial search turned up more than 200 images of fuzzy red arcs. They then used the Wyoming Infrared Observatory, near Laramie, to follow up on 80 of these candidates and identify the sources behind the suspected bow shocks. Most turned out to be massive stars.

The findings suggest that many of the bow shocks are the result of speedy runaways that were given a gravitational kick by other stars. However, in a few cases, the arc-shaped features could turn out to be something else, such as dust from stars and birth clouds of newborn stars. The team plans more observations to confirm the presence of bow shocks.

"We are using the bow shocks to find massive and/or runaway stars," said astronomer Henry "Chip" Kobulnicky, also from the University of Wyoming. "The bow shocks are new laboratories for studying massive stars and answering questions about the fate and evolution of these stars."

Another group of researchers, led by Cintia Peri of the Argentine Institute of Radio Astronomy, is also using Spitzer and WISE data to find new bow shocks in space. Only instead of searching for the arcs at the onset, they start by hunting down known speedy stars, and then they scan them for bow shocks.

"WISE and Spitzer have given us the best images of bow shocks so far," said Peri. "In many cases, bow shocks that looked very diffuse before, can now be resolved, and, moreover, we can see some new details of the structures."

Some of the first bow shocks from were identified in the 1980s by David Van Buren of NASA's Jet Propulsion Laboratory in Pasadena, California. He and his colleagues found them using infrared data from the Infrared Astronomical Satellite (IRAS), a predecessor to WISE that scanned the whole infrared sky in 1983.

Kobulnicky and Chick belong to a larger team of researchers and students studying and , including Matt Povich from the California State Polytechnic University, Pomona. The National Science Foundation funds their research.

Images from Spitzer, WISE and IRAS are archived at the NASA Infrared Science Archive housed at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.

Explore further: The bow shock of Kappa Cassiopeiae, a massive, hot supergiant

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11 comments

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Osiris1
3 / 5 (2) Jan 05, 2016
Maybe warp signatures will be similar to this......? Comments?
Mike_Massen
1.8 / 5 (5) Jan 05, 2016
Osiris1 offered
Maybe warp signatures will be similar to this......? Comments?
Perhaps, reminds me of the odd ultra high energy particles which fail good explanation via existing AstroPhysics ie
https://en.wikipe...particle

Being very rare & Very powerful may be consistent with aftermath of a craft (accelerating long enough so its relativistic speed is very high) colliding with debris.

Re Special Relativity & assuming the craft could sustain high g for long enough (re occupants/robots ref frame) its accumulated relativistic KE would be Immense !

Then a collision & especially so with anything of opposite direction may create spray of Oh-My-God particles. It would be of interest to determine some suitable signature re the spectra, Eg Polarisation factor re possible artificial origin but, those energies a very sophisticated detector is needed

Its an odd thought; could be civilization with robots exploring in high g craft spreading out :D
Whydening Gyre
5 / 5 (5) Jan 05, 2016
Maybe warp signatures will be similar to this......? Comments?

There was a Star Trek; Next generation episode kind of about this...
Whydening Gyre
5 / 5 (5) Jan 05, 2016
Actually, I just wanna ask...
Does the material that is forming the bow shock, show up in any other way? Is it calculated into galactic mass measurements? Cuz this could be a way of spotting Dark matter that isn't so "dark" anymore...
Mike_Massen
1.8 / 5 (5) Jan 05, 2016
Tah, Whydening Gyre offering
Does the material that is forming the bow shock, show up in any other way?
Hmm, similar thought occurred to me however, although I accept DM as an algebraic place holder for missing gravitational effect, I'm not discounting an aspect of the n-body problem (over time) & in relation to Integral of all other energy sources of a 'shifted form'.
Eg Neutrinos have been shown to have different flavours with long equiv wavelength ie. there may be fourier series of wavelengths & the galactic environment may well illustrate a longer wavelength in a conjunction with a observed frame dragging
https://en.wikipe...dragging

Whydening Gyre pondered
Is it calculated into galactic mass measurements?
AFAIK, even with huge amount of this material & great number of bow shocks seems still less than DM accounts for & yes, might be noticeable with significantly enhanced instrumentation, yay to the experimental Physicists...
Whydening Gyre
5 / 5 (6) Jan 06, 2016
I guess what I'm saying is... is it visible to any other instruments? Is it just sparsely distributed standard matter that is experiencing friction heat from being jammed together by the (magnetic field of the?) fast moving star...?
Mike_Massen
1 / 5 (4) Jan 06, 2016
Whydening Gyre clarified
I guess what I'm saying is... is it visible to any other instruments?
If sufficient mass overall then it *should* likely be lensing re Light deflection near massive objects if it were comparable matter to which we already experience. Also visual effects re scattering, dust, debris etc in relation to spectroscopy surveys

Upon reflection on your post, maybe closer inspection of our own Milky Way (MW) re potential DM "transitional" regions might be worthwhile ie Close spectroscopic inspection of light path from MW center to us at spread wavelengths/intensities as mapped might show components of missing mass, if particular patterns, could then be checked elsewhere

Whydening Gyre asked
Is it just sparsely distributed standard matter that is experiencing friction heat from being jammed together by the (magnetic field of the?) fast moving star...?
If it was charged then intrinsically magnetic so as to be jammed then spectra shows
Whydening Gyre
5 / 5 (4) Jan 07, 2016
Whydening Gyre asked
Is it just sparsely distributed standard matter that is experiencing friction heat from being jammed together by the (magnetic field of the?) fast moving star...?

If it was charged then intrinsically magnetic so as to be jammed then spectra shows

I was also maybe thinkin'... spacetime warping around a speeding massive body could be the initial "bow wave point", leading to compression of mass molecules, thereby interactively heating enough for IR to instruments to see what wasn't evident before...
I mean, you'd need a HUGE amount of space for all the individual particles floating around in it, to lens light in even the tiniest way...
Altho, I did just read that the star's own stellar wind is what's doing the pushing, so maybe I'm wrong...
Tuxford
1 / 5 (2) Jan 07, 2016
So the committed merger maniac must conclude that these massive speedy stars are growing smaller as they expel matter. And he must conclude that they previously grew from accretion when they were idle, and somehow later likely got the boot from a much more massive companion disintegrating. Do we see many binary systems with both very massive stars? Even in a cluster, how likely is it that two stars come close enough to cause such a considerable boot?

In the alternative, what if the runaway star simply grows by itself over time from within, eventually growing large and active enough to develop the bow shocks observed?

Heresy: 1. opinion or doctrine at variance with the orthodox or accepted doctrine, especially of a church or religious system.

antialias_physorg
5 / 5 (2) Jan 07, 2016
Maybe warp signatures will be similar to this

Nope, because (if we posit Alcbierre style warp drives) space gets stretched back to normal once the bubble passes. Stuff would look the same afterwards. you'd only see a very (VERY), short 'blip' of distortion - like a gravity lensing effect - when the warp driven entity passes. And you'd see that in a line with the direction of travel, not a bowshock formation.

Does the material that is forming the bow shock, show up in any other way? Is it calculated into galactic mass measurements?
Since those regions average out with lower density regions behind the star I think no adjustment is needed.

Cuz this could be a way of spotting Dark matter that isn't so "dark" anymore...

Dark matter interacts only very little with ordinary matter (in all theories that are currently in the mix) so detecting it via bow shock isn't easy. DM concentrations might deform a bow shock, but only if they are very local.
my2cts
4 / 5 (4) Jan 07, 2016
So the committed merger maniac must conclude that these massive speedy stars are growing smaller as they expel matter. And he must conclude that they previously grew from accretion when they were idle, and somehow later likely got the boot from a much more massive companion disintegrating. Do we see many binary systems with both very massive stars? Even in a cluster, how likely is it that two stars come close enough to cause such a considerable boot?

In the alternative, what if the runaway star simply grows by itself over time from within, eventually growing large and active enough to develop the bow shocks observed?

Heresy: 1. opinion or doctrine at variance with the orthodox or accepted doctrine, especially of a church or religious system.


You are not making sense, which is a necessary condition to be a heretic.

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