Want to get up to speed on black holes? We’ve got you covered! A black hole is an object so dense that not even light can escape it. #BlackHoleWeek⚫ 1/6 go.nasa.gov/3OOqRNd
A black hole’s “surface” is its event horizon. Inside this boundary you’d have to go faster than light, the fastest thing in the universe, to escape the black hole. 2/6
The two main types of black holes that have been extensively observed are stellar-mass and supermassive. The type depends on how much stuff is crammed inside. Tens of times our Sun’s mass for a stellar-mass one; millions to billions for a supermassive one! 3/6
Stellar-mass black holes form when a huge star (one with at least 20 times the mass of our Sun) runs out of fuel. It collapses under its own weight and leaves behind a crushed remnant in the form of a black hole. 4/6
Supermassive black holes reside at the centers of most (and maybe all) large galaxies. Scientists are still trying to figure out where they come from. But we do know that they existed in the very earliest days of a galaxy’s lifetime. 5/6
What’s between the stellar and supermassive ones? “Intermediate mass” black holes have been elusive, but our telescopes have spied a few candidates and we’re eager to learn more about them! 6/6
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Just because black holes don’t emit light doesn’t mean they’re totally invisible to us. By studying hints that point to their existence, we can learn a lot about them! Follow this thread and read more here: tmblr.co/Zz_UqjZ-7BiySm…#BlackHoleWeek⚫ 1/6
One thing black holes can’t hide is their gravity. They affect their environment just like anything else in the universe that has mass. 2/6
For decades, scientists have tracked stars orbiting the black hole at the center of our galaxy. Using those observations, they’ve estimated the black hole holds 4 million times the mass of our Sun! 3/6
Our Swift satellite just detected its 1,500th gamma-ray burst! 🛰💥 This powerful explosion was observed on Oct. 23 in the constellation Ursa Major. To celebrate, let’s explore 3 other extra-special Swift observations from over 16 years of science. 🥳
Soon after launch, Swift was the first to spy a short gamma-ray burst with an afterglow — GRB 050509B lasted only 0.03 seconds! ⏱ Other telescopes followed up to continue the hunt for the cause of these bursts, later confirmed to be neutron star mergers. go.nasa.gov/2ZruPGO
Nearly all gamma-ray bursts have to be observed with telescopes. But in 2008, Swift caught a burst so powerful that its afterglow was briefly visible without any magnification. GRB 080319B may be the most distant object visible to unaided eyes! 👁 More: go.nasa.gov/3mePTIY
The Burst Alert Telescope, or BAT, on our Swift satellite just surpassed 1 million triggers! 🎉 The BAT constantly watches for gamma-ray bursts — powerful but fleeting explosions signaling a black hole’s birth. 💥 Get up to speed on gamma-ray bursts here: tmblr.co/Zz_Uqj2aNmOwb
☑️ The BAT’s onboard algorithms review each trigger to see if it’s a cosmic source or a statistical fluctuation. In sifting through those many triggers, Swift’s BAT has detected about 1,400 bona fide bursts along with a number of other notable discoveries.
👀 Let’s look at some.
The initial flash in some gamma-ray bursts lasts less than two seconds, making it hard to lock on to them for follow-up observations. ⏱️ Swift was designed to do just that and pinpointed its first “short” gamma-ray burst afterglow in May 2005. Learn more: go.nasa.gov/371jmip
#OTD in 2008, @NASA’s Fermi Gamma-ray Space Telescope began its science operations. In these 12 years, Fermi helps open our eyes to better understand some of the most powerful cosmic sources like these:
On Aug 4, 2017, Fermi detected a powerful, short gamma-ray burst located 130 million light-years away. Those gamma rays had friends! @NSF’s LIGO also detected gravitational waves from this pair of colliding neutron stars. go.nasa.gov/31lcAzw
Almost every day Fermi detects gamma-ray bursts lasting from a fraction of a second to over 1,000 seconds. Many of these events signal the birth of a black hole. nasa.tumblr.com/post/176492220…
This week, the stars of Eta Carinae made their closest approach — about the distance between Mars & the Sun — to each other occurring every 5.5 years. As the most massive, radiant & unstable star system within 10,000 light-years, it could even be the next bright supernova.
The larger of the two stars in Eta Carinae is a luminous blue variable about 90 times the mass of our Sun. Though rare now, we think these “superstars” were common in the early universe, when they were fundamental in forming the first black holes.
The smaller star (about 30 times the mass of the Sun) is outshone by its larger companion making it tough to directly detect. But it has found a way to make itself known! Its stellar wind collides with the wind of its comrade which creates very hot gas and a strong X-ray signal.