Featured Research

from universities, journals, and other organizations

Scientists Begin To Tease Out A Hidden Star's Secrets

Date:
July 27, 1998
Source:
University Of Wisconsin-Madison
Summary:
Peering deep inside obscuring cocoons of stardust, astronomers are beginning to witness the birthing secrets of an unusual star.

MADISON, Wisc. -- Peering deep inside obscuring cocoons of stardust, astronomers are beginning to witness the birthing secrets of an unusual star.

Related Articles


Using a small, specially equipped telescope at the Kitt Peak National Observatory, as well as powerful radio telescopes such as the Very Large Array (VLA), University of Wisconsin-Madison astronomer Edward Churchwell has spent a career dissecting dense clouds of interstellar dust to reveal the mechanisms by which O stars, some of the largest and rarest in the cosmos, come to life.

By doing so, Churchwell and others who study the hidden giants are gaining important new clues to how the stars form, a phenomenon that, if unmasked, can help portray issues of cosmic importance such as how most of the mass in the universe gets lumped into stars and how objects from tiny neutron stars to massive galaxies spew out material in the form of bipolar jets.

"There are many puzzles in this whole area," said Churchwell. And although they burn brightly in infrared wavelengths, "you can't see them in visible light, and they are very rare."

There are only about 20,000 O stars in the entire Milky Way, a galaxy with nearly 4 billion stars. And O stars, when they form, are hidden deep inside dense cocoons of dust, just a few light years across, called ultracompact H II regions, making them all but inaccessible to the bulk of astronomical telescopes. Moreover, they are distant from Earth. The closest is 1,500 light years away in the Orion Nebula.

But using sensitive infrared and radio telescopes to cut through the interstellar murk, Churchwell and a small cadre of other astronomers are accumulating enough evidence to construct a hazy picture of O star nurseries. Writing in the most recent issue of the Astrophysical Journal, Churchwell and his colleagues report observations of 21 ultracompact H II regions that are helping depict them as very large, but hollow dust cocoons with steep temperature gradients, and a burst of starmaking activity with dozens of nascent stars at their cores.

"Nobody knows how these stars are formed, but it's clear they have to accrete a lot of mass over a short period of time," said Churchwell of the jumbo baby stars, each being anywhere from 10 to 100 times more massive than the sun.

Smaller stars like the sun seem to form alone while massive stars like O stars come in bunches. Small infant stars also have what astronomers call accretion disks, a swirl of gas and stardust that surrounds a star and falls onto it over time. But how massive stars like O stars obtain the bulk of their mass, gaining the equivalent of a sun every thousand years, is a mystery, said Churchwell.

Solving these mysteries, he said, would go a long way toward explaining how material cycles in and out of stars, how galaxies evolve and a slew of unanswered questions in astrophysics.

One example, said Churchwell, is the mystery of bipolar jets, massive outflows of gas and dust from the polar regions of galaxies and stars, including O stars. How those jets are produced and driven is a central mystery of astrophysics. "There is more mass in these jets than the stars themselves, and if only 20 percent of the mass (of material around a star) falls into it, how do you throw the remaining 80 percent out in these jets? That is a big problem because there is something universal about these jets of outflowing material."

Another conundrum posed by the stellar nurseries is why they are hollow. What force is it that carves out space within the ultracompact H II regions, leaving only a bevy of nascent stars at their cores? Is it the 2,000-kilometer-per-second solar winds from the massive stars that blow the dust away? "We're not sure," said Churchwell. "There are a number of possibilities."

For Churchwell, who's been observing jets in his stellar nurseries, one idea is that much of the matter around the star never makes it into the star itself, but through unidentified processes -- possibly radiation and thermal pressure -- is funneled outward into the jets.

Churchwell acknowledged that while there is still no definitive view of these star nurseries, the slow accumulation of facts through observation is beginning to flesh out theory. We don't have all the answers yet, he said, but some of the pieces are beginning to fall into place.


Story Source:

The above story is based on materials provided by University Of Wisconsin-Madison. Note: Materials may be edited for content and length.


Cite This Page:

University Of Wisconsin-Madison. "Scientists Begin To Tease Out A Hidden Star's Secrets." ScienceDaily. ScienceDaily, 27 July 1998. <www.sciencedaily.com/releases/1998/07/980727081019.htm>.
University Of Wisconsin-Madison. (1998, July 27). Scientists Begin To Tease Out A Hidden Star's Secrets. ScienceDaily. Retrieved November 25, 2014 from www.sciencedaily.com/releases/1998/07/980727081019.htm
University Of Wisconsin-Madison. "Scientists Begin To Tease Out A Hidden Star's Secrets." ScienceDaily. www.sciencedaily.com/releases/1998/07/980727081019.htm (accessed November 25, 2014).

Share This


More From ScienceDaily



More Space & Time News

Tuesday, November 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Feast Your Eyes: Lamb Chop Sent Into Space from UK

Feast Your Eyes: Lamb Chop Sent Into Space from UK

Reuters - Light News Video Online (Nov. 25, 2014) Take a stab at this -- stunt video shows a lamb chop's journey from an east London restaurant over 30 kilometers into space. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Soyuz Spacecraft Docks With International Space Station: NASA

Soyuz Spacecraft Docks With International Space Station: NASA

AFP (Nov. 24, 2014) A Russian Soyuz spacecraft carrying Italy's first female astronaut safely docks with the International Space Station, according to NASA. Duration: 00:40 Video provided by AFP
Powered by NewsLook.com
Multi-National Crew Safely Docks at Space Station

Multi-National Crew Safely Docks at Space Station

Reuters - US Online Video (Nov. 24, 2014) A Russian Soyuz rocket delivers a multi-national trio to the International Space Station. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Raw: Soyuz Docks With Int'l Space Station

Raw: Soyuz Docks With Int'l Space Station

AP (Nov. 23, 2014) A Russian capsule carrying three astronauts from Russia, the United States and Italy has arrived at the International Space Station. (Nov. 23) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins