Black Holes Grow Big by Eating Stars
Cambridge, MA (SPX) Apr 10, 2012
” Most galaxies, including the Milky Way, have a supermassive black hole at their center weighing millions to billions of suns. But how do those black holes grow so hefty? Some theories suggest they were born large. Others claim they grew larger over time through black hole mergers, or by consuming huge amounts of gas.
New research by astronomers at the University of Utah and the Harvard-Smithsonian Center for Astrophysics (CfA) shows that supermassive black holes can grow big by ripping apart double-star systems and swallowing one of the stars.
“Black holes are very efficient eating machines,” said Scott Kenyon of the CfA. “They can double their mass in less than a billion years. That may seem long by human standards, but over the history of the Galaxy it’s pretty fast.” “
Jesus vs. scientists: Who’s better at miracles?
How do scientists stack up to Jesus when it comes to feeding the masses, turning water into wine and making the blind see?
Financial Times: Syrian opposition wary of jihadist push
“Jihad is the only way to avenge the killing of our brothers,” says the narrator as the camera zooms in on roadside bombs taking out Syrian security vehicles. “Peaceful demonstrations will get you nowhere … this regime is supported by Israel and the US … it will only be finished with blood.”
The scene is part of a 45-minute video recently posted on jihadi websites by a group calling itself the Nasra Front, which now appears to be waging a propaganda campaign to exploit Syria’s more than one-year-old uprising.
The video depicts a weeping mother relating how she was allegedly raped by regime forces and a young suicide bomber pledging to avenge atrocities committed in the city of Homs.
As Syria’s crisis has shifted from peaceful demonstrations to unseat Bashar al-Assad to a more militarised conflict involving thousands of low-ranking defected soldiers and ordinary men who have taken up arms, it has raised the enthusiasm of jihadis for what they see as a potentially new battlefront.
No one is certain who the Nasra Front is. It first surfaced with a claim of responsibility for bombings in Damascus and Aleppo at the beginning of this year. Members of the Syrian opposition dismiss it as a creation of the regime intended to sully the image of a revolution it has long blamed on Islamist extremists, part of a strategy aimed at scaring minorities into supporting the Assad government. Others suspect that it might be linked to a group of Syrian, Lebanese and Palestinian jihadis hiding in a Palestinian refugee camp in Lebanon.
Photo: FSA member on patrol in Idlib, FreedomHouse/Flickr
Why do you really want a new car?
Anyone who owns a car has felt that itch to get a new one at some point. We see the newer models drive by, and our mind begins to think about how great it would be to ditch our old ride for something shiny and new that doesn’t have crumbs filling the seat cracks.
But, think for a moment about the reasons you could be tempted into trading in your car for a new one. You’re at the car dealership looking at the sun glinting off the hood. You climb into the driver’s seat and take notice of the shiny dashboard, the freshly vacuumed carpet, and the wonderful smell. You glance over at your old car and notice how crummy it looks in comparison. Sure, it drives fine, but it just seems so…meh.
Now, think about what’s actually selling you here. It’s not that the car is new. It’s the fact that it’s clean. You’re just yearning for a car that isn’t filled with dust and the smell of old french fries.
The good news is, you can have that without dropping $20,000 on a new car.
You might be surprised at how much more appealing your car is after it’s been washed, waxed, and detailed. That’s how the dealerships can buy a 10 year old car for $2,500 and then turn around and sell it for $5,000.
Many people view a car detail as an unnecessary expense. But, if spending $100 on a thorough cleaning keeps you from taking on a new monthly car payment, it’s actually one of the best financial moves you could ever make.
Tornadogenesis—the formation of tornadoes—remains a topic of active research as there is relatively little direct experimental data, owing to the difficulty of prediction as well as measurement. Initially, a variation of wind speed at different altitudes in the atmosphere causes shearing, which can lead to the formation of a horizontal column of rotating air—a vortex line similar to a roll cloud. Beneath a developing storm, the updraft of warm local air can pull this vortex line upwards, creating vertical rotation in the cloud, thereby birthing a supercell. Supercells do not always spawn tornadoes, and the exact causes that result in tornadic or nontornadic supercells are not fully understood. However, the formation of tornadoes within the supercell seems dependent on the downdraft of cool air within the storm as well as stretching of the vortex line, which increases its rate of rotation. For more information, check out this explanatory video and some of the talks by Paul Markowski. (Thanks to mindscrib, aggieastronaut and others for their submissions related to this topic! Photo credits: P. Markowski and D. Zaras)
The stellar factories are 7,500 light years away in the Carina Nebula. The 150 light-year-wide object contains dense fields of hydrogen gas and dust that, when they collapse, spawn extremely large, bright and short-lived stars. Just a few million years later they detonate as supernovas. By comparison, our much-smaller sun may last for another 5 billion years. The cataclysmic blasts push nearby gas into denser masses, sparking the birth of more stars.
Image: ESO/APEX/T. Preibisch et al.; N. Smith, University of Minnesota/NOAO/AURA/NSF [high-resolution version]