There is a release of new astronomical data by the European Space Agency satellite called “Gaia.” The main purpose of GAIA is to report accurate distances to stars in the Milky Way. GAIA does this by measuring parallaxes. This method relies on measuring what we might colloquially call “perspective.” The idea is that a high precision snapshot of a nearby star will make a pattern on the sky with respect to its fixed stellar neighbors. If you then wait for six months and take another snapshot image of that same nearby star, you will see a slightly different pattern. The Difference between the two images is called parallax. Physically, what happens is that view of a nearby star against the background of fixed stars change when the Earth is one one side of its orbit compared to when the Earth is on the other side of its orbit. Similar an artist will paint a completely different picture of the same … Continue reading →
About Dr. Brenda Frye
Brenda L. Frye is an observational cosmologist with research interests in the area of the formation and evolution of galaxies. She earned her Ph. D. in Astrophysics from the University of California at Berkeley, assisted by a National Science Foundation Graduate Research Fellowship. Her thesis work involved measuring the physical properties of faint and distant galaxies which are boosted artificially in brightness by natural telescopes in space, an approach that enabled her to study galaxies when the universe was less than one billion years old.
Moving a mile from her Ph. D. institution, she assumed a postdoctoral position with the Supernova Cosmology Project at Lawrence Berkeley National Laboratory under the direction of Physics Nobel Prize winner Professor Saul Perlmutter. She then crossed the country to hold two consecutive postdoctoral fellowship positions at Princeton University.
She has taught physics and astronomy at the undergraduate and graduate levels at Dublin City University in Ireland, the University of San Francisco, and the University of Arizona where she is currently Associate Professor of Astronomy.
The working definition of a galaxy is a huge collection of stars whose motions we do not understand. It was therefore a surprise when a galaxy was recently discovered whose motions we do understand. This new type of galaxy is called an Ultra Diffuse Galaxy (UDG). Astronomers usually ascertain the mass of a galaxy by observing the speeds of the stars and star clusters that orbit it. There is a straightforward formula which relates the speed of the stars with the mass of the galaxy. The Sun and the Earth, for example, move at a speed of 475,000 miles per hour about the center of the Milky Way. From this fact we work out that the mass of the Galaxy is about 300 billion times the mass of the Sun. But what is this mass anyway? Well, embarrassingly we cannot even see the majority of the mass in the Milky Way. Put another way, there is some form of material, … Continue reading →
A result was announced last week that the supermassive black hole at the center of our Galaxy has company in the form of 10,000 much smaller stellar mass black holes. We think that supermassive black holes are situated in the centers of most galaxies. The one in Milky Way has a mass of about 3-4 million times the mass of the Sun. This “invisible” astronomical body assimilates any object that hits its surface or “event horizon,” with the result being to grow its size. This is similar to how a fan of hamburgers and french fries “assimilates” that tasty fare in the form of a big tummy. It is thought that there are a great many examples of the much smaller stellar mass black hole varieties, which are the ones formed by the explosions of massive stars. Or, at least it is thought that there _were_ many examples of this stellar black hole variety. That is before these unsuspecting small … Continue reading →
There is interest on behalf of our readers to know more on the discovery by Professor Stephen Hawking that black holes radiate away, or equivalently, lose mass over time. Black holes are, well, black. They are hard to find and even harder to study. A black hole does have a surface which is called an event horizon. Unlike a surface of any planet, however, the event horizon is a point of no return. Any object that falls inside of this surface is lost forever. The popular version of the story of Hawking radiation starts by reminding us that particles are created and destroyed in pairs constantly all over space. The plot takes shape when one of these particle-antiparticle pairs appears very very near the event horizon. The fate of such an unlucky couple is that if one particle wanders out of the event horizon then it will escape, leaving the other one imprisoned behind the event horizon. The plot is … Continue reading →
It happened – the world’s largest telescope to be in space has been delayed by another year. This refers to the James Webb Space Telescope or “JWST,” the successor to the famous Hubble Space Telescope or “HST.” I first started working on the JWST as a Lecturer in Dublin, Ireland in 2006. The task was to test one of the four JWST instruments called the Mid InfraRed Instrument (MIRI). We worked hard to make the components “space ready” by simulating their performance in a cryogenic facility under vacuum at Rutherford Appleton Laboratory in England. No one got to go inside the vacuum, as it has no air (among other things), but we did get to run the simulations by sending software commands from a climate-controlled room adjacent to the chamber. Meanwhile, the other three instruments were tested at other cryogenic facilities in different countries. By 2018 all instruments had been individually tested, assembled, and tested again, then moved to Northrop … Continue reading →
The great physicist Stephen Hawking helped us to appreciate that black holes really exist. In this week’s article in Sky and Telescope there is discussion on yet another new type of ultra-compressed object called a “semiclassical relativistic star.” Although not nearly as catchy as “black hole,” the semiclassical relativistic star has the advantage of being made out of real matter. After all, stars are made out of real matter. The standard lore has it that a massive star unlucky enough to run out of hydrogen fuel will explode as a supernova, leaving behind a neutron star or a black hole. This week we ask the relatively new question: what if there is also a third choice? In this article physicist Carballo-Rubio considers what happens if we introduce additional quantum mechanics considerations on top of what we already know about black holes. In particular, he wanted to find out how that ill-fated massive star responds to the effects of quantum fluctuations. … Continue reading →
The world has lost a great luminary of science. Brother Guy Consolmagno called Hawking a “scientist of admirable intuition, who knew even more extraordinarily to give a human face to cosmology and to astronomy.” Professor Hawking had a significant public following. I recall learning this lesson first-hand when he gave a public talk while I was a graduate student at the University of California at Berkeley. There was so much interest that we had to book a venue to hold the hundreds of ticket-holders. I recall volunteering to serve as an usher. Later I would find out just how very much ushers were needed at this popular event. This is because dozens of disabled individuals found their way to this auditorium. I recall that Professor Hawking offered advice. He said not for everyone to see him as a role model and study mathematics, but rather for each person to find out what one does best and then do that one … Continue reading →
The James Webb Space Telescope (JWST), the most anticipated telescope to follow the wildly successful Hubble Space Telescope, is now safely ensconced in Los Angeles, California, where it will get fully outfitted with four giant solar shields and endure some final pre-launch tests. Following this last bit of human interaction, the telescope will get folded, placed into a European Ariane 5 rocket, and then pushed along to its launch site. Stepping back a few years, I was lucky enough to get to be an instrument tester for two of the instruments on this grand telescope, the European-built Mid-Infrared Instrument (MIRI), and the U. S.-built Near-Infrared Camera (NIRCam). The procedure is to place the instruments into a vacuum to simulate the environment in outer space. We then would turn on the instruments and make sure they worked according to specs. The testing duties involved writing computer algorithms, performing quality checks on the incoming data, and carefully saving all the technical information. … Continue reading →
When did the first stars turn on in the universe? This grand question motivates new observations that may change the way we think about the first stars and, in a surprising turn of events, also about the mysterious dark matter in which the stars are embedded. The discovery is reported in the most recent issue of Nature magazine by Principal Investigator Dr. Judd Bowman. Dr. Bowman and his team of astronomers used a radio telescope for this experiment which operates at frequencies close to your those of your favorite radio stations on the FM dial! The idea is that if there were stars existing when the universe was a mere 180 million years old, then the starlight would change the absorbing properties of the abundant neutral hydrogen atoms surrounding the stars. This change would allow an absorption to be detected by the hydrogen as it interacts with the all-pervasive cosmic microwave background radiation. Astronomers expected that there would eventually be … Continue reading →
Astronomers have known that the universe is expanding with time ever since Edwin Hubble made the discovery in 1929. This started a quest to determine the exact rate of this universal expansion, also known as Hubble’s constant which is still in progress. The base requirement is to find a way to make a reliable measurement of the distance. There are many ways to make the measurement. One approach that is especially useful is to employ a certain type of supernova called SN 1a as a tool for calibrating distances. This is valuable as the SN 1a is a standard candle. By a standard candle we mean that the object in question has a certain quantity about it that is known and measureable, which in this case is its brightness. Using the SN 1a as a tool, the astronomer and Nobel Laureate Professor Adam Riess and collaborators announced a new best-value for the measurement Hubble’s constant. They made the press release … Continue reading →
In a worrying development from the past week, a satellite slated to advance our understanding of dark energy just got zeroed out of NASA’s budget. The modern version of the story began in 1998/1999 with the announcement that supernovae at great distances are fainter than they ought to be. The interpretation of this measurement is that the universe is accelerating away from us. This discovery resulted in a Nobel Prize for three U. S. scientists, one of whom was an undergraduate peer of mine at the University of Arizona by the name of Brian Schmidt! As exciting as it was, the discovery was also bizarre and unexpected. Up until that time we had thought that the universe merely expanded like a balloon until it reached a maximum extent, and then closed back in on itself. The discovery of dark energy, on the other hand, means that the universe is accelerating away from itself. In this sense dark energy gives us … Continue reading →
I opened up a university lecture a handful of years ago by asking a group of first year students if any of them had ever seen a rocket launch. I called on the first person to raise his hand. The reply was, “Yes, an Apollo mission!” That would have been fine, except that the individual looked all of the 18 years old that he was supposed to be. Indeed many decades ago NASA did have a rocket called “Saturn V” which took humans on a series of Apollo missions to the Moon (and this is also the rocket that installed the mini space station called “Skylab”). Unfortunately, with the end of the Apollo missions in 1973 also came the end of the heavy lifters. The Space Shuttle entered the scene in 1981. Although not quite as powerful as the Saturn V, it was capable of taking people into space, that is until it was decommissioned in 2011. Finally, just this … Continue reading →