Making massive stars

Sep 10, 2010
A model of a massive young star being formed as gas accretes onto the protostar and a disk that encircles it. The arrows indicate the direction and velocity of the flow; the white lines are density contours. Credit: Eric Keto and Qizhou Zhang

Massive stars -- those with more than about eight times the mass of the sun -- are arguably the most important actors in the universe. Much hotter and more luminous than the sun, they live only hundreds of millions of years before exploding in supernovae, but during their lives their nuclear furnaces produce a wide range of chemical elements (the universe was created with primarily hydrogen and helium).

Meanwhile they heat up their galactic neighborhoods and dominate the properties of their environments and their gas and dust. In their dramatic deaths they seed the universe with these elements (and others produced in the cataclysm), disrupt their neighborhoods, and leave behind or sometimes .

Massive stars are much less common than sun-sized stars, comprising only a few tenths of a percent of all stars, and astronomers wonder why. It is not clear if standard ideas about apply to massive stars. For example, do they grow like smaller stars by accreting material from a large envelope while also surrounded by a rotating disk of material?

Massive stars mature very quickly, however, in less than a few hundred thousand years compared with millions of years for stars like the sun, and as a result there are not many young ones around at any given time in which to study the processes associated with their birth.

Two SAO astronomers, Eric Keto and Qizhou Zhang, argue in a new paper that do form like smaller ones, at least with respect to their envelopes and disks. Combining observations of molecular gas in one young, massive star with computer models of star formation that were scaled up to fit this more massive case, they find very good agreement, at least with stars of masses up to ten solar masses (stars more massive than this may yet have differences).

The results not only suggest that theorists are on the right track, they imply that future observations of massive young with new instruments can expect to see the signatures of these disks in their data.

Explore further: How baryon acoustic oscillation reveals the expansion of the universe

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User comments : 4

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omatumr
1.7 / 5 (6) Sep 10, 2010
Recent research suggests that our Sun and most other stars formed on the gravitational well of a compact nuclear object and then generate more H than they consume by these three steps:

a.) Neutron-emission produces a free neutron
b.) Neutron-decay produces Hydrogen
c.) Stellar wind discharges Hydrogen to interstellar space

With kind regards,
Oliver K. Manuel
Former NASA Principal
Investigator for Apollo
Skeptic_Heretic
Sep 10, 2010
This comment has been removed by a moderator.
omatumr
2 / 5 (4) Sep 10, 2010
What reseach Dr. Manuel?


Research over the past 50 years, from 1960 to 2010. To quote from our most recent paper:

"As noted in the abstract, the discovery of neutron repulsion in 2000 was the triumphant arch through which many puzzling observations over the previous four decades could finally be viewed as pieces of a surprisingly simple mosaic of the origin, chemical composition and source of energy for the Sun and its planetary system."

With kind regards,
Oliver K. Manuel
Former NASA Principal
Investigator for Apollo


Skeptic_Heretic
5 / 5 (1) Sep 11, 2010
What reseach Dr. Manuel?


Research over the past 50 years, from 1960 to 2010. To quote from our most recent paper:

"As noted in the abstract, the discovery of neutron repulsion in 2000 was the triumphant arch through which many puzzling observations over the previous four decades could finally be viewed as pieces of a surprisingly simple mosaic of the origin, chemical composition and source of energy for the Sun and its planetary system."

With kind regards,
Oliver K. Manuel
Former NASA Principal
Investigator for Apollo



So this is your own, unpublished, unreviewed research...
omatumr
1 / 5 (2) Sep 14, 2010
No, SH, my research is published.

1. "Attraction and repulsion of nucleons: Sources of stellar energy", J. Fusion Energy 19, 93-98 (2001).

2. "Nuclear systematics: III. The source of solar luminosity", J. Radioanal. Nucl. Chem. 252, 3-7 (2002).

3. "The Sun's origin and composition: Implications from meteorite studies", ESA-SP- 500 (editor: Barbara Warmbein), pp. 787-790 (2003).

4. "The standard solar model versus experimental observations", BEYOND 2002 (IOP, Bristol, editor: H. V. Klapdor-Kleingrothaus) pp. 307-316 (2003).

5. "Neutron repulsion confirmed as energy source", J. Fusion Energy 20, 197-201 (2003).

6. "Composition of the solar interior: Information from isotope ratios", ESA SP-517 (editor: Huguette Lacoste) pp. 345-348 (2003).

Etc., etc.

Yours?