Took a few students up to a nice spot overlooking Mount Rainier where we had previously noticed ground fog forming later in the day. We were lucky and eventually got a 2 hour window...this is a test from that brief opening...well worth the wait and cold... Had to sacrifice a fuller star-field for the beautiful moonlight on the mountain and ground fog... BTW: Those of us with lens dew-not dew heaters/controllers from Smart Astronomy (ruby123 on ebay) had a dew/frost free night...those without didn't... great practice for the upcoming shoot on Mauna Kea ;-) Nikon D7000 w/ 14-24 @14mm / F 2.8 ISO 800 for 10 secs w/ 3 sec intervals+ More details
The Mass and Growth of Black Holes Xue-Bing Wu, Department of Astronomy, Peking University, Beijing 100871, China Since black holes do not emit light, detecting them is a big challenge to us. However, nowadays black holes with different masses and scales are widely believed to exist in our universe. Using the huge ground-based and space telescopes astronomers have discovered numerous black holes, especially those with mass of a few solar masses existed in our Galaxy and those with mass of a few million to billion solar masses existed in the center of nearby and distant galaxies. Although we can not see the black holes directly, we can probe the strong gravity of black holes by observing the stars and gas near to them. Various dynamical methods and empirical relations have been adopted by astronomers to reliably estimate the masses of supermassive black holes in both inactive and active, nearby and distant galaxies. There are clear evidences for the existence of supermassive black holes with several billion solar masses in the very early universe. But how these masive black holes can form and grow in a relatively short time is still under debate. How massive are the seed black holes for them? How to form the seed black holes? Can they rapidly grow by continuous mass accretion or galaxy-galaxy merge? Future studies with more giant telescopes will help us to answer these questions. Further reading: (1) Black Holes FAQ (Frequently Asked Questions) List by Ted Bunn (http://cosmology.berkeley.edu/Education/BHfaq.html) (2) "Supermassive Black Holes in Galactic Nuclei: Past, Present and Future Research" by Laura Ferrarese & Holland Ford, 2005, Space Science Reviews, Volume 116, Issue 3-4, pp. 523-624 (http://arxiv.org/abs/astro-ph/0411247) (3) "Supermassive Black Holes in Nuclei of Galaxies" by John Kormendy & Karl Gebhardt, 2001, AIP conference proceedings, Vol. 586. Edited by J. Craig Wheeler and Hugo Martel, p.363 (http://arxiv.org/abs/astro-ph/0105230)+ More details
Living Black Holes Shuang Nan Zhang, Physics Department and Center for Astrophysics Tsinghua University, Beijing, 100084, China Except for mini- or quantum black holes predicted but not observed so far, all other black holes start up as dead-bodies of massive stars or clusters of stars. Yet, those black holes we can detect and study today are living and interacting with their environments, and sometimes even grow together with their host galaxies if found in centers of galaxies. A stellar mass black hole found in company with a normal star may accrete matter from its companion and produce strong X-ray/gamma-ray radiation, as well as relativistic outflows/jets. Similar phenomena also occur for supermassive black holes that are 6-9 orders of magnitudes more massive and found in centers galaxies, as they are supplied with abundant material from their host galaxies. In fact the feedback from the radiation and outflows from the central black holes also have a strong bearing on the evolution of their hosts. Despite of the apparent importance of black holes’ playing in the cosmic history, several burning questions still remain unanswered: (1) How are stellar mass black holes formed when massive stars exhaust their nuclear fuel and gravitationally collapse? A massive star may collapse quietly to become a black hole, or experience a supernova, or even a hypernova, which are the most energetic explosions since the Big Bang; (2) How does a stellar mass black grow to become a supermassive black hole within the cosmic age? Perhaps some exotic modes of mass accretion take place, or the seed black hole may even accrete dark matter surrounding it to grow quickly in the beginning and then starts to accrete normal matter in its host galaxy; (3) Observationally how to determine the demographics of black holes? Perhaps determining their masses and maybe also their angular momenta will help us understand many of the above questions; (4) What happens when a neutron star and a black hole, or two black holes, or two neutron stars merge together to form another black hole? Perhaps strong gravitational radiations are produced. It is often argued that direct detection of gravitational waves from black holes may provide ultimate proof of the existence of black holes, and thus the unambiguous verification of Einstein’s General Relativity.+ More details
TelescopeMan records the December 2011 ATMSIG meeting of the Texas Astronomical Society, which featured a World War II aircraft camera lens which will be converted into a 4 inch refractor. www.texasastro.org www.telescopeman.org www.telescopeman.us www.telescopeman.info+ More details
The annual Geminid meteor shower, which peaks on December 13/14, was a fascinating show in 2009, the best seen Geminid shower for many skygazers. The shower is created as planet Earth sweeps through dusty debris from extinct comet Phaethon. In this early morning time-lapse video from Zagros mountains of Iran about two dozen shooting stars flash in the sky near Sirius, the brightest star of our night-time. On the right side, stars of Orion (with the notable Orion Nebula) set in the western horizon. See a stunning still image of a striking bright meteor in this video here: www.twanight.org/?ID=3002287 All rights reserved by Babak Tafreshi (www.twanight.org) and The World at Night (TWAN) program.+ More details
The stars have inspired humans since the beginning of time. When we look up, we see endless possibilities. Three stargazers share their thoughts about the universe and our place in it. “The Cosmos is all that there is or ever was or ever will be. Our feeblest contemplations of the Cosmos stir us—there is a tingling in the spine, a catch in the voice, a faint sensation, as if a distant memory, of a failing from a height. We know we are approaching the greatest of mysteries.” -Carl Sagan MUSIC Dreaming by Lee Rosevere Cloudburst by Jeff Thall+ More details
A time lapse video (my second ever... still learning) showing the constellation of Orion, also featuring the Large Magellanic Cloud and Small Magellanic Cloud. Photography by Roger Groom in Perth, Western Australia. Taken with a Canon 7D. Panning uses an AstroTrac configured horizontally.+ More details
An invitation to quantum gravity. Laurent Freidel, Perimeter Institute In this talk I will present the problem of quantum gravity from a broad perspective . I will try to emphasize what are the challenges that one face when addressing this question and what are the different routes one can take to address them. I will then focus on one approach sometimes called loop quantum gravity which focus on one core issue: background independence. Namely the fact that the geometry of space time is a dynamical entity whose nature at the quantum scale needs to be determined dynamically. I will review some of the main ideas of this approach for instance the fact that one can associate discrete quantum states to what one would call space in the classical realm. I will also present some of the results obtained in this approach concerning for instance, black holes, cosmology or the coupling to matter. I’ll try to outline some of the many challenges that lies ahead.+ More details
Light from the Early Universe and Quantum effects in Gravity Eva Silverstein, Stanford University Inflationary cosmology -- exponential expansion of the universe at early times -- provides a simple, observationally tested scenario for understanding the observed flatness and homogeneity of the universe and the seeds of structure formation. Within this broad framework, there are diverse mechanisms for theoretically modeling inflation and structure, many of which make distinctive predictions for observations of the Cosmic Microwave Background Radiation (CMBR). The mechanism behind inflation is sensitive to very high-energy physics, and requires input from a more complete theory of gravity (such as string theory) going beyond Einstein's General Relativity. After introducing the phenomenon of early universe inflation, I will describe two effects of interest -- gravitational radiation, and nonlinear effects in the CMBR -- and their role in the challenging problem of trying to connect string theory to observations.+ More details
What are Tags?
Tags are keywords that describe videos. For example, a video of your Hawaiian vacation might be tagged with "Hawaii," "beach," "surfing," and "sunburn."