Dust, blowing in the wind

Apr 25, 2011
An optical image of the globular cluster, 47 Tucanae. Astronomers have studied the many stars in this cluster to learn more about how dust is produced in the winds of its older stars. Credit: South African Astronomical Observatory

(PhysOrg.com) -- Interstellar space contains vast quantities of dust that obscures our view while helping to catalyze the chemical reactions that turn atomic gases into complex molecular species. Most dust is made in the winds of older stars (called asymptotic giant branch, "AGB," stars) that have completed the hydrogen burning phase of their lives. The sun is still in its "main-sequence" stage of life. Astronomers think that the process of dust manufacturing is quite general, and is also responsible for dust seen in the early universe. Although dust production is important, exactly how it is made remains a mystery.

A number of factors complicate the research effort. It is difficult to measure adequately the winds that generate dust in many faint stars. It is hard to determine the grain properties like size, density, shape, or composition. Not least, no one knows how dust production varies among AGB stars of different masses or evolutionary stages, or the precise role of in driving the winds.

To help sort out these and other issues, CfA astronomers Joe Hora and Tom Robitaille joined with thirteen colleagues to examine closely the globular cluster 47 Tucanae, a massive collection of millions of stars in our galaxy that has the research advantage that all its stars formed at about the same time, and all are at about the same distance from us.

The team used observations of the cluster's stars across the spectrum from the visible wavelengths through the infrared, and in particular they relied on infrared observations from the . They modeled statistically the emission of the stars to establish their range of physical parameters (mass, for example), and to model the evolution of the system. Writing in the new issue of the , they report that the distance to the cluster is 15,040 light-years with an uncertainty of about 4%, and it has an age of 12 billion years with an uncertainty of 8%. As for dust, they report that nearly all stars brighter than about 2000 solar luminosities are dust factories; most stars with half this luminosity or less do not produce dust. The result resolves a earlier debate about the dust production in fainter stars, and helps to pin down the masses and characters of the primarily responsible for making dust that blows in their winds.

Explore further: New mass map of a distant galaxy cluster is the most precise yet

Related Stories

Planets Living on the Edge

Dec 17, 2008

(PhysOrg.com) -- Some stars have it tough when it comes to raising planets. A new image from NASA's Spitzer Space Telescope shows one unlucky lot of stars, born into a dangerous neighborhood. The stars themselves ...

The Cosmic Distance Scale

Jan 29, 2010

(PhysOrg.com) -- In 1908, Harvard astronomer Henrietta Swan Leavitt discovered that a class of stars called Cepheids have brightnesses that vary regularly with periods that are directly related to their intrinsic ...

Destroyer of worlds

Sep 24, 2010

(PhysOrg.com) -- Astronomers, in addition to discovering extrasolar planets (about 500 of them currently have known orbital parameters), have detected excess, warm infrared dust emission around many stars.

Chandra Lifts the Veil on Milky Way 'Hotspot'

Jan 23, 2008

NASA's Chandra X-ray Observatory is helping to demystify Westerlund 2, a young star cluster with an estimated age of about one- or two-million years. Heavily obscured by dust and gas, Westerlund 2 has been ...

Young Star Clusters

Oct 12, 2009

(PhysOrg.com) -- Most stars form in clusters. Recent studies of nearby star forming regions find that about three-quarters of their young stars are located in groups with ten or more members. The formation ...

Recommended for you

Satellite galaxies put astronomers in a spin

10 hours ago

An international team of researchers, led by astronomers at the Observatoire Astronomique de Strasbourg (CNRS/Université de Strasbourg), has studied 380 galaxies and shown that their small satellite galaxies almost always ...

Video: The diversity of habitable zones and the planets

11 hours ago

The field of exoplanets has rapidly expanded from the exclusivity of exoplanet detection to include exoplanet characterization. A key step towards this characterization is the determination of which planets occupy the Habitable ...

Ultra-deep astrophoto of the Antenna Galaxies

11 hours ago

You might think the image above of the famous Antenna Galaxies was taken by a large ground-based or even a space telescope. Think again. Amateur astronomer Rolf Wahl Olsen from New Zealand compiled a total ...

The most precise measurement of an alien world's size

12 hours ago

Thanks to NASA's Kepler and Spitzer Space Telescopes, scientists have made the most precise measurement ever of the radius of a planet outside our solar system. The size of the exoplanet, dubbed Kepler-93b, ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Bigblumpkin36
1 / 5 (1) Apr 25, 2011
Take that bible people