Biggest 'small' black hole discovered

October 19, 2007

New Haven, Conn. -- Discovery of the largest example of a "small" black hole -- one formed from the collapse of a single massive star at the end of its lifetime -- has led scientists to revaluate of how black holes come into being, according to a report in Nature.

"The theory we operated with for the last decade was that single-star black holes are formed from the remnants of massive stars -- the more massive the star, the more massive the remnant. But, all of the stellar mass black holes were expected to be in the range of 10 times the mass of the sun or less, since only the core regions of the star would collapse," said Charles Bailyn, the Thomas E. Donnelley Professor of Astronomy and Physics at Yale, and a member of the research team.

The research team, who identified the black hole with 15.65 times the mass of the sun, took advantage of "nature" to make an unusually precise measurement and required the surprised astronomers to reevaluate a long-standing theory.

Since black holes can't be seen -- because they trap all matter and light that enters them -- they are detected by the gravitational effects they have on nearby stars or other matter that is near them. This team made their calculations by measuring the motion of a star as it orbited abound the black hole, known as M33 X-7. The black hole completes one orbit every 3.45 days around its massive companion star.

"In this particular case, an eclipse in the system provided the exact orientation and gave mass information far more accurate than any previous reports," said Bailyn. "Researchers rarely have such accurate points of reference."

While some other papers have cited "small" black holes with masses of 12 to 14 times that of the sun, Bailyn said, "Those data had large margins of error that could still fit within the theory. Finding a black hole with such unusual characteristic points out that our understanding of the evolution of massive stars and the formation of black holes must be incomplete."

This black hole is also the most distant stellar black hole ever observed and is located outside our galaxy -- in a dwarf galaxy, Messier 33, that orbits Andromeda. Bailyn noted that, "Finding black holes in different and distant locations gives us many more objects to study and opens up the opportunity to find extreme examples that test theoretical limits."
-end-
Lead author on the study is Jerome A. Orosz, associate professor in the Department of Astronomy at San Diego State University, and former graduate student who studied with Charles Bailyn at Yale. Other authors are Jeffrey McClintock, Ramesh Narayan, Joel Hartman, Jiefeng Liu, Lucas Macri, Wolfgang Pietsch, Ronald Remillard, Avi Shporer and Tseve Mazeh.

Scientists combined data from three observatories to make their discovery --NASA's Chandra X-ray Observatory in orbit around the Earth, the Gemini North 8-meter telescope on the island of Hawai'i, and the 2.1-meter and WIYN 3.5-meter telescopes at Kitt Peak National Observatory near Tucson were combined to make the discovery. Support for the study came from the National Science Foundation.

For more information on black holes, see Charles Bailyn's "Black Hole Toolbox": http://cmi2.yale.edu/bh and the Chandra Observatory press release: http://chandra.harvard.edu/press/07_releases/press_101707.html .

For graphics and images, including an optical image of the galaxy M33 from Kitt Peak, see: http://chandra.harvard.edu/photo/2007/m33x7/more.html

Citation: Nature (October 19, 2007).

Yale University

Related Black Hole Articles from Brightsurf:

Black hole or no black hole: On the outcome of neutron star collisions
A new study lead by GSI scientists and international colleagues investigates black-hole formation in neutron star mergers.

The black hole always chirps twice: New clues deciphering the shape of black holes
A team of gravitational-wave scientists led by the ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav) reveal that when two black holes collide and merge, the remnant black hole 'chirps' not once, but multiple times, emitting gravitational waves--intense ripples in the fabric space and time--that inform us about its shape.

Wobbling shadow of the M87 black hole
New analysis from the Event Horizon Telescope (EHT) Collaboration reveals the behavior of the supermassive black hole in the center of the M87 galaxy across multiple years, indicating the crescent-like shadow feature appears to be wobbling.

How to have a blast like a black hole
Scientists at Osaka University have created magnetized-plasma conditions similar to those near a black hole using very intense laser pulses.

Black hole collision may have exploded with light
Astronomers have seen what appears to the first light ever detected from a black hole merger.

Black hole's heart still beating
The first confirmed heartbeat of a supermassive black hole is still going strong more than ten years after first being observed.

Black hole team discovers path to razor-sharp black hole images
A team of researchers have published new calculations that predict a striking and intricate substructure within black hole images from extreme gravitational light bending.

Planets around a black hole?
Theoreticians in two different fields defied the common knowledge that planets orbit stars like the Sun.

Black hole mergers: Cooking with gas
Gravitational wave detectors are finding black hole mergers in the universe at the rate of one per week.

Going against the flow around a supermassive black hole
At the center of a galaxy called NGC 1068, a supermassive black hole hides within a thick doughnut-shaped cloud of dust and gas.

Read More: Black Hole News and Black Hole Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.