Probe opens a new window to interstellar space

Jan 16, 2005

Taking stock of the stuff between the stars - the all-important dust and gases that are the building blocks of new stars - has never been easy.
The interstellar medium, as scientists know it, is a murky, nebulous place that defies easy measurement. Yet probing the space between the stars and the star-building materials that reside there is increasingly important as astrophysicists seek to add precious detail to their pictures of how stars are born, live and die.

Now, with help from a novel new device, a team of University of Wisconsin-Madison astrophysicists has successfully developed a method for sampling the interstellar medium, specifically to take the temperature of and explore the pockets of ionized oxygen interspersed between the stars of the Milky Way.

"This is a first for studies of our galaxy," says Ron Reynolds, a UW-Madison professor of astronomy and an authority on the chemical soup of elements that permeates the space between the stars.

With colleagues John Harlander of St. Cloud State University and Edwin Mierkiewicz, UW-Madison physics Professor Fred Roesler constructed and deployed a new type of instrument capable of sampling wide swaths of the sky and exploring the vast clouds of ionized oxygen that well up from the plane of the galaxy. The new device was built with support from the National Science Foundation (NSF).

Data from the first observations using the new spectrometer, which is attached to a small telescope at UW-Madison's Pine Bluff Observatory, were presented by Merikiewicz here today (Jan. 13, 2005) at a meeting of the American Astronomical Society (AAS).

The new observations, taken by Mierkiewicz during the past year, reveal enormous chimneys of ionized gas that rise from the galactic plane into the far corners of the Milky Way.

"The galaxy seems to be full of channels or chimneys of ionized hydrogen, oxygen and nitrogen gas," says Reynolds. "The source is down in the muck where stars are born, but these channels seem to extend into the nooks and crannies of the galaxy."

That discovery, according to Mierkiewicz and Roesler, is intriguing because it provides insight not only to the patchwork of elements that make up the interstellar medium, but also to a class of rare stars that seems to be primarily responsible for the heating and churning that creates the chimneys of gas.

The stellar culprits, known as "O stars," are the most massive and luminous of stars, shining as much as a million times brighter than the sun.

"O stars are the only known stars that can create that much ionization," says Reynolds. "These are very rare stars - one in 10 million stars is an O star - but we see that they have a large influence on the interstellar medium. At this point, if there were other objects creating that much ionization, we'd know about them."

The picture that is emerging, according to Roesler, is that the O stars, which tend to occur in clusters near stellar nurseries, act as galactic blenders of sorts: "They are responsible for the ionization - the stripping of electrons from atoms - and the stirring up of the oxygen."

The Spatial Heterodyne Spectrometer, the new spectrometer developed by the Wisconsin team, looks at ultraviolet light, which is invisible to the unaided eye, but is laden with information for astrophysicists. The new technique, says Mierkiewicz, is especially useful as a temperature probe, and gives scientists a new way to take the temperature of the invisible clouds of gas that permeate space.

Teasing out the details of the interstellar medium is important, the scientists say, because each new finding helps fill in the picture of the life cycle of stars and, ultimately, of galaxies like the Milky Way.

In addition to Mierkiewicz, Roesler, Harlander and Reynolds, K.P. Jaehnig of UW-Madison contributed to the work presented at the AAS meeting. The new Wisconsin spectrometer was developed with support from NSF's Advanced Technology Instrumentation Program.

Source: University of Wisconsin-Madison

Explore further: Full lunar eclipse delights Americas, first of year

add to favorites email to friend print save as pdf

Related Stories

Research group to study interstellar molecules

Apr 11, 2014

From April 2014, a new group will study interstellar molecules and use them to explore the entire star and planet formation process at the Max Planck Institute for Extraterrestrial Physics. Newly appointed ...

Hubble monitors supernova in nearby galaxy M82

Feb 26, 2014

This is a Hubble Space Telescope composite image of a supernova explosion designated SN 2014J in the galaxy M82. At a distance of approximately 11.5 million light-years from Earth it is the closest supernova ...

Galaxy collisions

Apr 09, 2013

Collisions between galaxies are common. Indeed, most galaxies have probably been involved in one or more encounters during their lifetimes. One example is our own Milky Way, which is bound by gravity to the ...

Betelgeuse braces for a collision

Jan 22, 2013

(Phys.org)—Multiple arcs are revealed around Betelgeuse, the nearest red supergiant star to Earth, in this new image from ESA's Herschel space observatory. The star and its arc-shaped shields could collide ...

Recommended for you

Astronomers: 'Tilt-a-worlds' could harbor life

11 hours ago

A fluctuating tilt in a planet's orbit does not preclude the possibility of life, according to new research by astronomers at the University of Washington, Utah's Weber State University and NASA. In fact, ...

Vegetables on Mars within ten years?

17 hours ago

The soil on Mars may be suitable for cultivating food crops – this is the prognosis of a study by plant ecologist Wieger Wamelink of Wageningen UR. This would prove highly practical if we ever decide to ...

NASA Cassini images may reveal birth of a Saturn moon

17 hours ago

(Phys.org) —NASA's Cassini spacecraft has documented the formation of a small icy object within the rings of Saturn that may be a new moon, and may also provide clues to the formation of the planet's known ...

User comments : 0

More news stories

Astronomers: 'Tilt-a-worlds' could harbor life

A fluctuating tilt in a planet's orbit does not preclude the possibility of life, according to new research by astronomers at the University of Washington, Utah's Weber State University and NASA. In fact, ...

NASA Cassini images may reveal birth of a Saturn moon

(Phys.org) —NASA's Cassini spacecraft has documented the formation of a small icy object within the rings of Saturn that may be a new moon, and may also provide clues to the formation of the planet's known ...

Vegetables on Mars within ten years?

The soil on Mars may be suitable for cultivating food crops – this is the prognosis of a study by plant ecologist Wieger Wamelink of Wageningen UR. This would prove highly practical if we ever decide to ...

Low Vitamin D may not be a culprit in menopause symptoms

A new study from the Women's Health Initiative (WHI) shows no significant connection between vitamin D levels and menopause symptoms. The study was published online today in Menopause, the journal of The North American Menopa ...