At a meeting of the American Astronomical Society in Kissimmee, Florida this week, astronomers working with data from the NASA Spitzer spacecraft and the WISE infrared space telescope presented their findings on a special class of stars associated with the so-called head shock wave.
Here are some of the stunning eye examples of “runaway stars” and their effects on interstellar gases:
As Spitzer captured, the Kappa Cassiopeia star (HD 2905) produces a dazzling infrared head shock wave. The stellar wind, the stars and the magnetic field collide with thin interstellar gases, highlighting the direction of the star-traveler (in the lower right part of the image).
During ocean cruises, the water in the bow of the ship will “push apart” and flow in the opposite direction. If we talk about space, as a result, this wave, known as the "head shock", will simply continue its journey. Now imagine a star feeding through the interstellar medium. She is engaged in pumping stellar gases. Stellar winds move in the direction of the star against interstellar gases and a shock wave. Depending on the conditions in the interstellar medium and the velocity of the latter, all collisions can be detected even from the Earth — hot gases can be seen using the infrared spectrum.
These stunning photos of Spitzer show the whole picture in detail. They can help study the process of fast star formation. This example shows how the star-traveler Zeta Ophiuchi (Zeta Ophelia) flies at a speed of about 54,000 miles per hour (or 24 kilometers per second) relative to its vicinity. "Runaways" are a special kind of stars. Only one of its shock waves says a lot about the origin of the host, the mass and so on.
Observations of Zeta Ophiuchi were included in the mission of the WISE apparatus. Its infrared cable, as seen in the photograph, is more diffuse than that of Spitzer. It looks like a mixture of dust and gases.
This shock wave provides some information about Zeta. So it is 20 times more massive than our Sun, it generates stronger winds and moves faster.
"Some stars get very heavy loads when their companions explode and force them out of the general star cluster," said William Chick from the University of Wyoming in Laramie at an AAC meeting. "The gravitational effect increases the speed of a star relative to others."
It is interesting that researchers also use Spitzer’s archived data to determine if new shocks are present throughout the galaxy. At the moment, about 200 signals are tracked. Although some of them are actually glowing star-forming nebulae, ground-based observatories have confirmed that most of them appeared precisely because of the “runaway” stars.
"We use the head shock wave to search for new massive runaway stars," said Henry "Chip" Kobulnik, also from the University of Wyoming. "New laboratories study massive stars with head shock waves, also looking for an answer to the question of their fate and evolution."
Another group of researchers who also presented their findings this week have a slightly different point of view.
"WISE and Spitzer provide us with the best photographs of the waves to this day," said Cynthia Peri of the Argentine Institute of Radio Astronomy. "Previously, they were less clear for us, but at the moment the problem has been solved. In addition, we can see some new features of the structure." Peri’s team first looks for runaway stars, and only then finds its head shock wave.
The diffuse glow of the shock wave of a star can also be seen in the images of Spitzer. The mass of all the runaway stars identified in this new study ranged from 8 to 30 solar masses.
Head shock waves were detected not only by WISE and Spitzer. The predecessor of WISE, an infrared astronomical satellite IRAS, scanned the entire sky in 1983 and detected the first luminous shock waves emerging from runaway stars.
The result of long-term observations of Hubble was a very young star Orion LL. The latter left behind a very pronounced head train. As young stars evolve rather quickly, they generate powerful stellar winds, the surrounding gases inside the star-forming nebula — in this case, inside the star at the center of the Orion nebula. The result of a collision of supersonic gases that feed through the nebulae can also create a head shock wave.
