Feeds

Hefty black hole weighs in at 33 Suns

Record-breaking stellar-mass heavyweight

Build a business case: developing custom apps

Researchers have confirmed that a black hole lurking in the dwarf galaxy IC 10, and dubbed IC 10 X-1, weighs in at up to 33 Suns, double the previous record for a "single star" black hole held by M33 X-7 which tips the scales at 16 Suns.

IC 10 X-1, lying 1.8 million light years from Earth, was first spotted back in 2007 by the US's Harvard-Smithsonian Centre for Astrophysics in Cambridge, New Scientist reports. Researchers estimated its weight at between 24 and 33 times the weight of our own Sun, but the result was speculative.

The researchers calculated the weight "based on the apparent orbit of a nearby companion star" deduced from "repeating dips in the brightness of X-rays coming from the black hole's vicinity" as the orbiting companion passed in front of a disc of hot, X-ray spewing material being sucked into the black hole.

Although they had no concrete evidence to back their figures, astronomers Jeffrey Silverman and Alexei Filippenko from the University of California at Berkeley have used spectra taken by the 10 metre Keck I telescope in Hawaii to confirm the result at between 23 and 33 solar masses.

The leeway in the black hole's possible weight is because the mass of its companion is unknown, NS explains.

While black holes can be "supermassive" monsters weighing billions of Suns, there's a limit on the size of black holes formed from the death of a single star - dubbed "stellar-mass" objects - depending on the star's mass and chemical make-up.

All stars lose material into space over their lifetimes, an amount determined by their chemical composition, and even the biggest bodies at up to 100 solar masses "can barely produce a 16-solar-mass black hole if they are born with a composition similar to the Sun's".

A more heavyweight prospect comes from stars "low in elements heavier than hydrogen and helium", according to astrophysicist Stanford Woosley of the University of California in Santa Cruz. These "cast off material less efficiently and could therefore have up to 42 solar masses available to form a black hole when they die".

Significantly, galaxy IC 10 "contains very few 'heavy' elements", NS notes.

IC 10 X-1 offers a possible explanation for "puzzlingly bright" X-ray sources spotted in other galaxies, so-called "ultra-luminous" sources which are 10 to 100 times brighter in X-rays than your average stellar-mass black holes. Some have suggested these are "intermediate mass black holes" weighing "hundreds or thousands of times" the mass of the Sun, which emit X-rays as they ingest matter.

However, Roy Kilgard of Wesleyan University in Middletown, Connecticut, reckons large stellar-mass black holes like IC 10 X-1, "undergoing especially bright outbursts of X-rays", could be the cause.

Kilgard suggests that there may be "many other stellar-mass black holes in this mass range that have eluded detection until now because they are farther away and harder to study", and concludes: "I expect in the coming years we'll identify many more of these things." ®

Note for commentators

Regarding the weight of IC 10 X-1 in Reg standard units, the Sun is reckoned to tip the scales at 1.9891 × 1030 kg. A Jub is, of course, 4.2kg.

We'll leave you to do the rest, and suggest the answer is probably best expressed in megaJubs.

Boost IT visibility and business value

More from The Register

next story
Just TWO climate committee MPs contradict IPCC: The two with SCIENCE degrees
'Greenhouse effect is real, but as for the rest of it ...'
Asteroid's DINO KILLING SPREE just bad luck – boffins
Sauricide WASN'T inevitable, reckon scientists
Brit amateur payload set to complete full circle around PLANET EARTH
Ultralight solar radio tracker in glorious 25,000km almost-space odyssey
Boffins spot weirder quantum capers as neutrons take the high road, spin takes the low
Cheshire cat effect see neutrons and their properties walk different paths
NASA Mars rover FINALLY equals 1973 Soviet benchmark
Yet to surpass ancient Greek one, however
Famous 'Dish' radio telescope to be emptied in budget crisis: CSIRO
Radio astronomy suffering to protect Square Kilometre Array
prev story

Whitepapers

Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Why and how to choose the right cloud vendor
The benefits of cloud-based storage in your processes. Eliminate onsite, disk-based backup and archiving in favor of cloud-based data protection.
The Essential Guide to IT Transformation
ServiceNow discusses three IT transformations that can help CIO's automate IT services to transform IT and the enterprise.
Maximize storage efficiency across the enterprise
The HP StoreOnce backup solution offers highly flexible, centrally managed, and highly efficient data protection for any enterprise.