Podcaster: Richard Drumm
Title: Space Scoop: How Massive is Supermassive?
Organization: 365 Days Of Astronomy
Link : astrosphere.org ; http://www.unawe.org/kids/unawe1805/
Description: Space scoop, news for children. Astronomers have just measured the masses of around 50 supermassive black holes or SMBHs in the distant Universe and found that each one is at least five million times more massive than our Sun!
This is the first time the masses of so many SMBHs that lie so far away have been directly measured, because studying black holes is hard.
Bio: Richard Drumm is President of the Charlottesville Astronomical Society and President of 3D – Drumm Digital Design, a video production company with clients such as Kodak, Xerox and GlaxoSmithKline Pharmaceuticals. He was an observer with the UVa Parallax Program at McCormick Observatory in 1981 & 1982. He has found that his greatest passion in life is public outreach astronomy and he pursues it at every opportunity.
Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by — no one. We still need sponsors for many days in 2016, so please consider sponsoring a day or two. Just click on the “Donate” button on the lower left side of this webpage, or contact us at signup@365daysofastronomy.org.
Transcript:
This is the 365 Days of Astronomy Podcast. Today we bring you a new episode in our Space Scoop series. This show is produced in collaboration with Universe Awareness, a program that strives to inspire every child with our wonderful cosmos.
How Massive is Supermassive?
We spend a lot of time talking about how massive cosmic objects are, but how massive is supermassive?
Sounds like a silly question, but think about it!
When we talk about something being massive, we’re not talking about its size or how large it is. Mass relates to how much material an object contains.
While a ball of cotton candy the size of your head is bigger than a chocolate bar, it contains less material, making it less massive. Try squashing it down with your hands and you’ll see what I mean!
There’s very little matter there.
A team of 42 astronomers have just measured the masses of over 40 supermassive black holes or SMBHs in the distant Universe and found a range of masses. The heaviest was about 1.7 billion solar masses and the lightest was about 4 million solar masses.
The SMBH in our own galaxy, the Milky Way, is about 4 million solar masses too.
This is the first time the masses of so many SMBHs that lie so far away have been directly measured, because studying black holes is hard.
Most telescopes only measure light, but black holes have gravity so strong that even light can’t escape their pull. This makes them invisible to our optical telescopes and means that scientists have to be extremely creative when it comes to studying them.
To measure these black hole masses, astronomers used a technique called reverberation mapping. This is where we look at the brightness of material, like cosmic gas and dust, close to the black hole and compare it to the brightness of material that’s farther away.
They got most of their data from the Sloan Digital Sky Survey at Apache Point Observatory in New Mexico.
Anything that changes the brightness of the inner material will also affect the outer material, but a little later. It takes time for the light to travel from the accretion disk to the gas clouds at the speed of light.
By measuring this time delay, astronomers can calculate how far the gas is from the black hole and use this information to measure its mass — even though they can’t see the details of the SMBH itself!
Hey, Here’s A Cool Fact:
Weight is how we experience mass here on the surface of the Earth. The floor under your feet and the rocks under that, are supporting you and they prevent you from falling all the way to the Earth’s core.
So what we call weight is the effect of gravity on a mass when the object is prevented from free falling by being supported physically.
More massive things will weigh more down here. But go out into orbit and you’ll experience weightlessness. The same experience is had when you’re in a falling elevator.
You will still have mass, but you’ll not experience weight. The Earth will not be preventing you from moving toward its center because when you’re in orbit you’re going sideways and are in constant free fall.
The falling elevator isn’t in constant free fall. When it reaches the bottom of the elevator shaft you’ll feel weight again. And rapid deceleration too!
Ouch!
Now go out to the Moon and a 50 kilo mass that weighs 110 pounds on Earth now weighs 18 pounds. It’s still 50 kilos, though, it’s mass in unchanged.
Thank you for listening to the 365 Days of Astronomy Podcast!
End of podcast:
365 Days of Astronomy
=====================
The 365 Days of Astronomy Podcast is produced by Astronomical Society of the Pacific. Audio post-production by Richard Drumm. Bandwidth donated by libsyn.com and wizzard media. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. This year we will celebrates the Year of Everyday Astronomers as we embrace Amateur Astronomer contributions and the importance of citizen science. Join us and share your story. Until tomorrow! Goodbye!