Featured Research

from universities, journals, and other organizations

Researchers Seek 'Heart' Of Black Hole Mystery

Date:
January 10, 2003
Source:
National Aeronautics And Space Administration
Summary:
New research, funded by NASA and the University of Tokyo, has shown astronomers may not yet have uncovered the mystery at the heart of one of the Galaxy's oldest star systems, the globular cluster M15.

New research, funded by NASA and the University of Tokyo, has shown astronomers may not yet have uncovered the mystery at the heart of one of the Galaxy's oldest star systems, the globular cluster M15.

In September, observations made using NASA's Hubble Space Telescope (HST) seemed to indicate the presence of a mid-size black hole, several thousand times more massive than the Sun, in the hearts of two clusters of stars. The observations were the foundation for a claim that intermediate-mass black holes had at last been discovered. By comparison, stellar-mass black holes are only a few times the mass of our Sun. Galactic-center black holes are millions or even billions of times more massive than our Sun.

New detailed computer simulations, published in the Astrophysical Journal, show a different way to interpret the same data. Instead of a new mid-size black hole of unknown origin in M15, the Hubble data have a more mundane explanation - a dense clump of stellar remnants, the products of normal stellar evolution, in the cluster's core. The cluster may contain a small black hole or maybe none at all. The simulations did not address the other star cluster, called G1, in which evidence for an intermediate-mass black hole was reported at around the same time as the M15 results were released.

The question of what lurks at the center of M15 has kept astronomers busy for at least two decades. At various times, claims have been made that M15 must harbor a central black hole. The claims were based on the high density of stars in the cluster's congested core and on other tantalizing hints. Hints like stars near the center seemed to be orbiting faster than would be expected if only their own gravity were binding them to the cluster. This would be the telltale gravitational signature of an unseen mass hiding in M15's core.

A team of astronomers used the HST for several years to probe M15's secrets. A few months ago, the answer to the decades-long question of the possible black hole in M15 seemed to be at hand. After a painstaking analysis of HST data, using earlier model calculations by Indiana University researchers, the team reported evidence for a central black hole.

Within hours of the team's announcement, astronomers around the world were carefully studying the paper and its exciting conclusions, which were also rather surprising, since the Indiana group had previously published models that produced high velocities near the center of M15 without the need for a black hole.

An international group of researchers, using the world's fastest computer, the GRAPE-6 system in Japan, were engaged in a series of simulations of star clusters that resembled M15. They used the GRAPE-6 to perform independent tests of the M15 black hole claim. The GRAPE's detailed, star-by-star simulations represent the state of the art in cluster modeling. Using this unique tool, the team found they could reproduce the M15 observations without the need for a central black hole. The GRAPE team's members are Jun Makino and Holger Baumgardt, of Tokyo University; Piet Hut, of the Institute for Advanced Study in Princeton, N.J.; Steve McMillan, from Drexel University in Philadelphia; and Simon Zwart, from the University of Amsterdam in the Netherlands.

When the GRAPE researchers notified the HST team of their results, they learned the Hubble team, along with members of the Indiana University group, had reached a similar conclusion. All three groups agreed that a black hole, if present, had to be significantly smaller than originally reported. One of the figures in the original paper, published by the Indiana group, had been labeled incorrectly, throwing off the later analysis of the Hubble observations.

The GRAPE group's results appear in the Jan. 1, 2003, issue of the Astrophysical Journal. The amended Hubble results are in January's Astronomical Journal. An addendum to the earlier paper by the Indiana group will appear in the March 1, 2003, issue of the Astrophysical Journal.


Story Source:

The above story is based on materials provided by National Aeronautics And Space Administration. Note: Materials may be edited for content and length.


Cite This Page:

National Aeronautics And Space Administration. "Researchers Seek 'Heart' Of Black Hole Mystery." ScienceDaily. ScienceDaily, 10 January 2003. <www.sciencedaily.com/releases/2003/01/030110192346.htm>.
National Aeronautics And Space Administration. (2003, January 10). Researchers Seek 'Heart' Of Black Hole Mystery. ScienceDaily. Retrieved September 2, 2014 from www.sciencedaily.com/releases/2003/01/030110192346.htm
National Aeronautics And Space Administration. "Researchers Seek 'Heart' Of Black Hole Mystery." ScienceDaily. www.sciencedaily.com/releases/2003/01/030110192346.htm (accessed September 2, 2014).

Share This




More Space & Time News

Tuesday, September 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: NASA Captures Solar Flare

Raw: NASA Captures Solar Flare

AP (Sep. 1, 2014) NASA reported the sun emitted a mid-level solar flare, on August 24th. NASA's Solar Dynamics Observatory captured the images of the flare, which erupted on the left side of the sun. (Sept. 1) Video provided by AP
Powered by NewsLook.com
Space Shuttle Discovery's Legacy, 30 Years Later

Space Shuttle Discovery's Legacy, 30 Years Later

Newsy (Aug. 30, 2014) The space shuttle Discovery launched for the very first time 30 years ago. Here's a look back at its legacy. Video provided by Newsy
Powered by NewsLook.com
Experiment Tests Whether Universe Is Actually A Hologram

Experiment Tests Whether Universe Is Actually A Hologram

Newsy (Aug. 27, 2014) Researchers at Fermilab are using a device called "The Holometer" to test whether our universe is actually a 2-D hologram that just seems 3-D. Video provided by Newsy
Powered by NewsLook.com
SpaceX’s Falcon 9 Rocket Explodes After Liftoff

SpaceX’s Falcon 9 Rocket Explodes After Liftoff

Newsy (Aug. 23, 2014) The private spaceflight company says it is preparing a thorough investigation into Friday's mishap. Video provided by Newsy
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:
from the past week

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