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NEW PODCAST: Quasars in Galaxy Clusters! May 19, 2011

Posted by jcconwell in Black Holes, Podcast, Quasars.
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http://365daysofastronomy.org/2011/05/17/may-17th-big-black-holes/

Description: Quasars are some of the most luminous objects in the universe. Quasars are ancient galaxies that harbor massive black holes at their centers. The black holes emit huge amounts of energy across the spectrum as they consume matter. In this podcast, Dara Norman discusses her research on how quasars interact with their environment. Many quasars occur in galaxy clusters which can play a role in turning on quasars as well as their evolution.

Bio: Dr. Dara Norman is a research astronomer at the NOAO. Her research interests are in the area of Active Galactic Nuclei, including Quasars, and their cluster environments, in particular the triggering of AGN, and their influence on galactic evolution. She is also interested in how Quasars can be used to understand large-scale structure in the universe.

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NEW PODCAST:What’s New With Supermassive Black Holes January 18, 2011

Posted by jcconwell in Astronomy, Black Holes, General Relativity, Podcast.
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What’s New With Supermassive Black Holes by Rob Knop
For the third year the physics department is sponsoring monthly podcasts at 365 days of astronomy

Description: Of all astronomical objects, there are few that inspire the imagination more than black holes. I’ll tell you about a couple of results that have come out recently having to do with supermassive black holes.
Rob Knop obtained a PhD in Physics from Caltech in 1997. He then worked with the Supernova Cosmology Project and was part of the discovery that the expansion of the Universe is accelerating. After six years as an assistant professor at Vanderbilt University, he worked in the computer industry for two years. He now teaches physics the new college Quest Unviersity in British Columbia. He gives regular astronomy talks in Second Life in association with the Meta-Institute of Computational Astronomy.

New Podcast: An Introduction to Active Galactic Nuclei February 21, 2010

Posted by jcconwell in Black Holes, Galaxy, Podcast.
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Active Galactic Nuclei (AGNs) are formed when enormous black holes consume material and spew out energy in jets many thousands of light-years long. This energy output, which can be up to a thousand times brighter than the galaxy itself, has a profound impact on the development of the host galaxy and its formation of new stars.

Podcaster: Olaf Davis & Renee Hlozek of the Oxford University Astrophysics Group

Bio: Olaf is a second-year PhD student in Oxford Astrophysics. His research involves computer simulations of astronomical phenomena – these include the behaviour of energetic particles around the jets of AGNs, and also the large-scale distribution of galaxies across the Universe. His blog, the Cosmic Web, is about astronomy and aimed at the layman.

Renee is in her second year, at Christ Church college Oxford, reading for a degree in Astrophysics. Her research interests include Dark Energy and decoding information contained in the Cosmic Microwave Background radiation, Baryon Acoustic Oscillations and Type-Ia Supernovae. She’s also interested in new methods of parameter estimation and forecasting. She’s passionate about outreach and public understanding of science.

http://365daysofastronomy.org/2010/02/21/february-21st-an-introduction-to-active-galactic-nuclei/


Astronomy Club Tonight! January 13, 2010

Posted by jcconwell in Astronomy.
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At 8:00 PM tonight in room 2153 Physical Science Building.

Bill Wolf will be giving a talk on his REU work over the summer at Syracuse University,  modeling astrophysical jets.

New Results from AAS Press Conference on Black Holes: Including Charleston Native, Dr. Julia Comerford January 10, 2010

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An image of the galaxy COSMOS J100043.15+020637.2 taken with the Advanced Camera for Surveys on the Hubble Space Telescope. Image courtesy Dr. Julia Comerford.

The 215th AAS (American Astronomical Society) meeting was just completed in Washington DC. The wonders of new media will allow people to see some of the interesting topics. One of them I selected for todays blog is the news conference on Black Holes. There are five interesting talks seen on ustream, one of them by Dr. Julia Comerford, a researcher from UC Berkeley, who happens to have grown up here in Charleston.

http://www.ustream.tv/recorded/3739728

For a nice article by our friends at Universe Today on Dr.  Comerford’s talks, go to the link below.

http://www.universetoday.com/2010/01/04/dual-black-holes-spinning-in-a-cosmic-dance-–-complete-with-disco-ball/

Top 10 Ways the Universe Could Kill Us! July 24, 2009

Posted by kfarley in Asteroid, Astronomy, Cosmology.
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Asteroid Impact

Asteroids and other near-Earth objects (NEOs) come near the Earth more frequently than one would guess. Question: Why don’t we ever hear of these objects hitting the Earth? Answer: Because they don’t. More often than not our atmosphere causes great friction on these solar bodies causing them to burn up. This happens before the asteroids can go through our atmosphere and hit the Earth. Our atmosphere can be a good friend to us – protecting us from solar debris that could potentially hit Earth and end civilization as we know it. If an asteroid were to make it through our atmosphere it becomes classified as a meteor. It is theorized that a large meteor hit the Earth about 65 million years ago wiping out the dinosaurs. According to NASA, a meteor about 1/5 that size will hit the Earth about once or twice every million years. If Earth did get hit by an asteroid of that caliber we would most likely not survive. I haven’t heard of an asteroid that size hitting the Earth in quite some time, maybe we’re overdue. With ≈6.7 billion people in the world your chance of seeing the Earth hit by that size meteor is…well, you do the math. To learn more information on NEOs check out NASA’s FAQs.

Illustration of an asteroid that could have wiped out the dinosaurs.

Illustration of an asteroid that could have wiped out the dinosaurs.

Solar Flare

A solar flare is a huge explosion of energy in the Sun’s atmosphere. Think of it like a giant spike of light and heat that suddenly rises off the surface of the Sun. The rays emitted (mainly X-rays and UV rays) from this explosion are strong enough to disrupt radio communication on Earth! The flares can influence the surface of Earth by having an effect on our weather. Just outside our atmosphere, the flares can present radiation hazards to spacecraft and astronauts. The solar flares can also produce streams of highly energetic particles in our atmosphere. These highly energetic particles help in the production of the beautiful aurora borealis! On the other hand, the radiation from solar flares also pose incredible complications that could arise during manned missions to Mars, the Moon, or other space travel. Satellites’ orbital paths can also be disrupted by the solar flares. Kind of a catch-22, amazing Northern lights produced but also possible space travel limit. Hmm…

Aurora borealis co-created by solar flares.

Aurora borealis co-created by solar flares.

Supernova

Ever had someone shine a flashlight in your eyes? Not very nice, huh? Think of shining a light in your eyes a billion times brighter! A supernova is just that – an exploding star billions of times brighter that our Sun. After the core of a star collapses it emits great energy as a flash of growing intensity before fading back out of sight. If a supernova was close enough and aimed toward our solar system, it could wipe out our atmosphere. Our planet would overheat from UV rays causing mass extinction. It’s messy too. The supernova will throw large clouds of dust and gas into space that could exceed 10 times the mass of our Sun. We should be thankful for supernovae in a way. It is hypothesized supernovae created the heavier elements such as gold, iron, and uranium found here on Earth.

Supernova.

Supernova.

Gamma Ray Burst

Gamma ray bursts (GRBs) are flashes of gamma rays that last from fractions of a second to almost an hour. They normally last a few seconds and usually come from outside our galaxy. They are the most luminous (electromagnetic) events that occur in the universe. GRBs often have an afterglow affect as longer wavelengths travel from the blast. The blast from a GRB in our galaxy would definitely cause mass extinction from the intense rays that would encompass our planet. It is hypothesized such an event caused the mass planetary extinction on Earth about 444 million years ago. A GRB depleted the ozone layer leaving our planet helpless to direct UV rays that heated and kill organisms until food chains were depleted.

P.S. Gamma rays gave the Hulk his powers (I think that is fictional though).

Illustration of a gamma ray burst hitting a planet like Earth.

Illustration of a gamma ray burst hitting a planet like Earth.

Black hole

Black holes are areas in space in which the gravitational field is so incredible that nothing can escape its pull. Not even light can be reflected from this object, hence its name. It is virtually impossible to escape a black hole once its immense gravitational pull has a hold of you. The point of no return at a black hole is called the horizon. It is an area just outside a black hole where the gravitational pull begins. Once you hit the horizon of a black hole your fate is sealed and escape from the black hole is futile. Knowing not even light can escape the pull of the black hole, you would have to travel faster than the speed of light to escape. If you were to see an object being pulled into a black hole (assuming the object can still reflect light), it would become extremely distorted. The gravitational pull is so intense, the part of the object entering the black hole first would stretch out of normal proportions. For example, if you were floating through space with your arms in front of you (Superman-style) and began to be sucked into a black hole, your arms would stretch out incredibly long before the rest of your body. Black holes are also very massive. They can range anywhere from 10 times to a million times the mass of our Sun. Currently, there are no known black holes in our galaxy. This known with the fact our space travel is limited to our Moon, you are probably safe from a black hole fate.

Illustration of what a black hole over the Milky Way might look like.

Illustration of what a black hole over the Milky Way might look like.

Death of Sun

The Sun goes through different stages during its life cycle. It’s about halfway through the “main sequence” before it goes into a different star phase. The Sun will most likely turn into a Red Giant star peaking at its highest luminosity. The Sun will then start to burn out as it turns into a small dwarf star. The Sun won’t turn into a Red Giant for another 5 billion years or so. A more immediate problem, as the Sun moves toward the next stage it becomes gradually warmer. It will get really hot. Life on Earth most likely won’t make it to the Red Giant stage. The Earth will warm up to the point where life will not be sustainable. The Sun has slowly been warming up ever since its birth. The Sun used to not be as hot, one of the reasons life didn’t always exist on the Earth. Just as the warmth of the Sun allowed life on Earth, it will also take it away.

The life cycle of our Sun.

The life cycle of our Sun.

Heat Death of Universe

The heat death of the universe occurs as all the stars and other universal matter continues to expand and uses up its energy or “burns out.” It’s like letting a candle burn and not blowing it out. Eventually it’s going to use up the wax and wick until it can’t burn anymore. The universe runs on “free” energy that is not endless. At some point the fuel for the universe will run out cutting of the energy for the cosmic bodies that give us life (namely our Sun). This probably won’t be happening anytime soon. It’s estimated the energy will run out after black holes vanish in about 10100 years (according to Hawking’s radiation). That’s one big candle!

The flame of life.

The flame of life.

The Big Rip

Just like how it sounds, all matter of the universe will be ripped apart.  We’ve all heard that the universe is expanding.  What would happen if the expansion increased at an accelerated rate?  If the universe expanded much faster than it is now, all the galaxies, stars, planets, dust, etc. would be ripped apart!  Think of it like a twizzlers.  If you pull slowly you can stretch out the twizzlers pretty far.  If you stretch too fast the twizzlers will just snap in half.  This is a possibility for our universe.  The hands pulling on our universe is something called dark energy.  Dark energy is a hypothetical energy that saturates all our universe.  It is theorized it helps our universe expand – at an accelerating pace.  This means the expansion is moving at a faster and faster rate as time goes by.  Eventually the universe will reach that point where it is pulling to fast, ripping apart everything.  What happens when everything is ripped apart and away from each other?  No one knows.

The Big Rip.

The Big Rip.

Cannibal Galaxies

Cannibal galaxies occur when a smaller galaxy is eaten by a larger galaxy! Natural selection at its best. Galaxies are gravitationally bound collections of stars, stellar bodies such as planets, space dust, and other objects. You are probably most familiar with the Milky Way galaxy (you should know this one, we live in it). Scientists can now detect our Milky Way galaxy is currently tearing apart and engulfing the Sagittarius galaxy as you read this! Closer to home than you might have expected. I guess we are saved this time but poor little Sagittarius galaxy…

Larger galaxy engulfing a smaller galaxy. (Swinburne)

Larger galaxy engulfing a smaller galaxy. (Swinburne)

Pulsar

When a star collapses on itself a neutron star is left behind. If we were to survive this giant explosion, we would have a new problem of pulsars to deal with. A pulsar is a neutron star that emits rays of electromagnetic radiation. Electromagnetic radiation is rays that vary depending on their frequency and wavelength. Some rays provide us with the visible light we use every day. Other rays below or above the spectra can be very harmful to us. For instance, radio waves (beyond red in the visible spectra) can vibrate the cells in your body heating them up to a deadly temperature while gamma rays (beyond blue in the visible spectra) can stop the function of the cells in your body. Oddly enough, both radio waves and gamma rays are used to treat different ailments.

The Vela Pulsar. NASA pic.

The Vela Pulsar. NASA pic.

Measuring the Black Hole July 9, 2009

Posted by jcconwell in Black Holes, General Relativity, IYA 2009, Podcast.
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Today’s podcast at 365 days of Astronomy is about measuring those mysterious objects, Black Holes. Usually you think about the tidal forces of a Black Hole ripping and compressing anything falling in until it’s so hot, about 10 million K, that it emits x-rays.

credit: NASA Chandra Space telescope

credit: NASA Chandra Space telescope

In today’s pod-cast sponsored by the EIU Physics Department learn how radio telescope aid our knowledge of these dark objects. Go to:

http://365daysofastronomy.org/2009/07/09/july-9th-measuring-the-black-hole/

Extreme Universe:Most Extreme Gamma-Ray Blast Ever! February 24, 2009

Posted by jcconwell in Astronomy, Extreme Universe, Gamma Ray Bursts.
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The explosion, designated GRB 080916C, occurred just after midnight GMT on September 16 (7:13 p.m. on the 15th in the eastern US). Two of Fermi’s science instruments — the Large Area Telescope and the Gamma-ray Burst Monitor — simultaneously recorded the event. Together, the two instruments provide a view of the blast’s gamma-ray emission from energies ranging from 3,000 to more than 5 billion times that of visible light.

gamma-ray-blast1

GRB 080916C's X-ray afterglow appears orange and yellow in this view that merges images from Swift's UltraViolet/Optical and X-ray telescopes. (Image courtesy NASA/Swift/Stefan Immler)

With the greatest total energy, and the highest-energy initial emissions ever before seen, a gamma-ray burst recently observed by the Fermi Gamma-ray Space Telescope set new records. The blast, which also raises new questions about gamma-ray bursts, was discovered by the FGST’s Large Area Telescope, a collaboration among NASA, the U.S. Department of Energy (DOE) Office of Science and international partners.

A team led by Jochen Greiner at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, established that the blast occurred 12.2 billion light-years away using the Gamma-Ray Burst Optical/Near-Infrared Detector (GROND) on the 2.2-meter (7.2-foot) telescope at the European Southern Observatory in La Silla, Chile.

“Already, this was an exciting burst,” says Julie McEnery, a Fermi deputy project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “But with the GROND team’s distance, it went from exciting to extraordinary.”

FGST team members showed that the blast exceeded the power of nearly 9,000 ordinary supernovae, using a distance of 12.2 billion light-years, and the gas emitting the first gamma rays must have moved at no less than 99.9999 percent the speed of light. This burst’s is the most extreme to date, in both power and speed .

Gravitational Waves and LISA January 11, 2009

Posted by jcconwell in Astronomy, Black Holes, General Relativity.
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The AAS meeting in Long Beach this week had many nifty displays. My favorite, since I’m biased toward  general relativity, is the LISA display. LISA stands for Laser Interferometer Space Antenna. Here I am in front of the full scale model of one of three proposed LISA satellites.

The author and a scale model of a LISA satelite

The author and a scale model of a LISA satellite

Now you may wonder why you want an orbiting gravitational wave satellite, especially since we have LIGO (Laser Interferometer Gravitational-Wave Observatory) already taking data. The answer is in the sensitivity diagram below

lisa-ligo_noise_spec1In order to make gravitational radiation you need to have an accelerated mass. The biggest masses with the largest accelerations are colliding black holes and neutron stars. Since most actual collisions are thought to be between orbiting bodies, the frequency of the radiation is related to the orbital frequency = orbits/second.

Now black holes seem to come in two classes. First, stellar mass black holes, created in massive core collapse supernovae. These black holes are around 10 solar masses and have a radius of 30 kilometers (18 miles). The greatest amount of radiation comes just as the two black holes are touching, or merging. The orbital velocities are about the speed of light. and the time to complete one orbit is

(orbital circumference) / velocity = .0006 second

or a frequency of 1600 orbits/second. This about the peak frequency for the radiation from this type of collision. In the diagram above, this frequency band is where LIGO was designed to be the most sensitive.

But there is a second class of black holes, the supermassive holes. These giants are from a million to several billion times the mass of the sun. They seem to form the core in most galaxies, and so when galaxies collide and merge, two orbiting monster black holes will release copious amount of energy. The good news is you can detect this from much further away than the merger of the smaller black holes. The bad news is the frequency.

A two million solar mass hole has a radius of 60 million kilometer and a circumference of about 380 million kilometers. In this case the period for the holes to orbit around each other is much longer

(orbital circumference) / velocity = 126 seconds

or a frequency of .008 orbits/second. A very low frequency, too low to detect on Earth, due earthquakes and seismic activities. This is where the frequency band where  LISA comes in and why you need it in space rather than on Earth.

Extreme Universe: Smallest Black Hole January 10, 2009

Posted by jcconwell in Astronomy, Black Holes, Extreme Universe.
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Not all records in astronomy are about the big stuff.  Good information comes in small packages. A classic case is XTE J1650-500, the smallest or lightest Black Hole measured.

Discovered in 2008 the lowest-mass known black hole belongs to a binary system.. The black hole has about 3.8 times the mass of our sun, and is orbited by a companion star, as depicted in this illustration.

smallbhjpg

Credit: NASA/CXC/A. Hobar

Using a new technique, two NASA scientists have identified the lightest known black hole. With a mass only about 3.8 times greater than our Sun and a radius of  11 kilometers, the black hole lies very close to the minimum size predicted for black holes, or the maximum mass neutron star that originate from dying stars.

The search for the smallest black holes is  important because of the information they tell us about neutron stars, which have a critical upper mass thought to no larger than 3 time the mass of the sun. This upper mass, very similar to the upper mass of white dwarf , which is about 1.4 Solar Masses called Chandrasekhar’s limit, is harder to calculate for the case of a neutron star.

Neutron stars have three extra complications, their rapid spin, the necessity of using general relativity to describe the gravitation, and most important, the nuclear forces at densities the exceed that of normal nuclei. Depending on the nature of the force you can get equations that relate the pressure and densities that very by a factor of 2 or more. resulting in different maximum mass neutron stars that depend on the nuclear force.

Thus the smallest black holes put constraints on the possible type of matter that make up neutron stars.