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IYA Is Off and Running! January 30, 2009

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Our thanks go to Dr. Pamela Gay for getting our celebration of the International Year of Astronomy off to a rousing start.

From Erin Matheny/The Daily Eastern News

Dr. Gay From Erin Matheny/The Daily Eastern News

Our thanks also to Dr. William Perry, president of EIU and Dr. Mary Ann Hanner , dean of the college of science for helping us launch IYA. Special thanks also to Sandy Durain for all her help organizing IYA.

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Observatory Open House Tonight January 30, 2009

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It looks like it’s going to be clear! So on come out and view the wonders of the constellation of Orion. Beginning with M42 the Great Nebula of Orion! Viewing begins at 8:00PM

First Astro-mural installed January 29, 2009

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If your in the physical science building for Dr. Gays talk tonight, come up to the second floor and sample a taste of the first of many Astronomy Murals that  will be appearing on the second floor in celebration of IYA. Your looking at the galaxy NGC 1300. A 100Mbyte mosaic from Hubble.

NGC1300 It looks spectacular up close.

NGC1300 It looks spectacular up close.

IYA at EIU kicks off with Dr. Pamela Gay TONIGHT!! January 29, 2009

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In Phipps Lecture Hall Tonight, 7:00 PMcur_iya2009

Astronomy Club Tonight January 28, 2009

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Astronomy Club in Room 2153  Physical Science Building at 8:00 PM tonight. Bill Wolf will be talking about dark energy. And for a preview the of the murals we are putting on the second floor look below!

The BIG Printer is Working

The BIG Printer is Working!!

In the event that you cannot come tomorrow, I’d like to take this
opportunity to remind you about our big speaker we have coming in on
Thursday, January 29. Dr. Pamela Gay of SIU will be our first of three
major speakers this semester in celebration of the International Year
of Astronomy. Her talk is entitled “The Once and Future Role of
Citizen Science: The Great Discoveries of Public Astronomers Across
History.” It will be held at 7:00 in Phipps Lecture hall in the
Physical Science Building. It would be GREAT to see you all there!

60th Anniversary of the 200″ telescope January 26, 2009

Posted by jcconwell in Astronomy.
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On January 26, 1949, sixty years ago today, the 200-inch Hale Telescope at the Palomar Observatory finally saw first light.  The effort to build the 200-inch telescope, then the world’s largest, began twenty one years earlier in 1928 when George Ellery Hale received a six million dollar grant for the project.  The telescope’s design, construction and final calibration phases spanned the Great Depression and World War II.

For more info go to 365 days of astronomy !

Look for the January 26 episode.

IYA at EIU, One Week From Today: Dr Pamela Gay January 22, 2009

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cur_iya2009

The event wil kick off EIU’s yearlong celebration of the International Year of Astronomy, a worldwide commemoration of many historic astronomical achievements, including the 400th anniversary of Galileo’s first look through a telescope and the 40th anniversary of man’s first steps on the moon.

Astronomy Club Tonight!! January 14, 2009

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Hello all, and welcome back to EIU. I hope you all had a wonderful
break.

We will be having a meeting tonight in room 2153 of the Physical
Sciences building at 8:00 PM. I’ll be speaking about the
International Year of Astronomy (IYA), which is this year in
celebration of both the 400th anniversary of Galileo’s first look
through a telescope and the 40th anniversary of man’s first steps on
the moon.

In addition, we will be heading over to Jerry’s after the talk for
some pizza (first pizza’s on me). So, I hope to see you
tonight at the meeting!

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

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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.