Posts by Dr. Brenda Frye

Digging up Astronomical Fossils
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Imagine looking up at the night sky. With our own eyes we can see at most a few thousand of the nearest stars to us. Now consider looking through a large telescope with a very large field of view. Through such an instrument millions of objects come into view, with most of these objects being galaxies, not stars. Interestingly, galaxies are not scattered randomly about the sky, as one might expect. Rather, they trace out a structure that looks a bit like a 3D spider web, called by astronomers the “cosmic web.” Fair enough. The story gets more interesting though when we find out that the mean separation between galaxies, equating roughly to the mean separation between the threads of a spider web, was set early on in the universe’s history. When the universe was only about 370,000 years old, various sound waves that traversed its extent were frozen into place by changing physical conditions. Astronomers maintain that events that … Continue reading

The Disappearing Star
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And now for the next trick, we will make a star disappear! Astronomers have just discovered a star in the Galaxy that is losing brightness fast. Although generally stable, a star can and does vary in brightness every so slightly during the adult phase of its lifetime. A star can slowly increase in brightness as it builds up more nuclear fusion products in its stellar center. This happens to all stars. For the Sun this amounts to a 30 percent increase in brightness since it formed 4.5 billion years ago. Eventually, in another 1 billion years, the Sun will be so hot that it will boil away the oceans (but let us not digress). Secondly, many stars brighten and fade on regular timescales of hours to years. These are wee brightness changes amounting to about 0.1 – 1 percent of the total flux on average, with some more extreme cases known especially for the smallest stars. There is one attribute … Continue reading

Connecting Religion and Intelligence over 230,000 years
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An archaeological discovery was announced from South Africa this week of new skeletal remains of Homo Naledi. Multiple age-dating techniques indicate that these early hominids lived an estimated 230,000 years ago. It was expected that they would have used their arms and legs much like humans do today, except that these beings would have had a brain only one-third that of modern humans. We refer to the blog from last week to learn how astronomy plays a role in such age measurements. Even so, there is new evidence that these hominids buried their dead deliberately in cave structures. From this behavior, archaeologists infer some level of religious ritual to have been present in their community. One wonders if this might be the first example of religious rituals. Expanding on this idea, one can wonder also by which process did these beings decide to build religious rituals into their lives? Finally one can take a step back and ask if religious … Continue reading

How Astronomy Helps Us Learn about the Mastodons
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An exciting discovery was made just this past week in the well-known Cerutti Mastadon site near San Diego, CA. Near to one of the mastodon skeletons was found also large stones that showed tell-tale signs to use as tools by early hominid visitors. What is interesting is not that people lived near San Diego before we called it by that name, but rather that hominids arrived there a full 115,000 years earlier than archaeologists had ever expected. Meanwhile the mastadons, a slightly smaller version of the mammoth, were commonly found in the Americas 130,000 years ago. A natural question to ask is how do we know that this particular mastodon site really is that old? Archaeologists determine ages by measuring the radioactive decay of certain elements like carbon or in this case uranium. Okay, fine, so where does the astronomy part fit in? Well in addition to the sunlight we appreciate so much in springtime, the sun also makes cosmic … Continue reading

Why the Upturn in UFO Sightings?
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A new book serves to document sightings of Unidentified Flying Objects (UFOs) in the past decade. The punch line is that UFO sightings are on the rise. When I discuss UFOs in my class I feel it is important to point out from the start that we have never found compelling evidence for life outside of Earth in any form. In fact, the term UFO refers simply to an object in the sky for which we do not know what it is. One can imagine that many of us do see UFOs by that description. The curious part is that when we see one, we do not stop there, but rather tend to jump suddenly to a conclusion such as to say “Oh, I don’t know what that is – that it must be a space ship from another planet that has come to Earth.” Why is that? Dr. Neil deGrasse Tyson remind us that there is a human tendency … Continue reading

Getting Baby Stars to “Dohsey-doh” Well with Others
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One hundred billion stars whirl about each other and, collectively, around the Galaxy, yet rarely do they ever collide. This is because stars are much more likely to interact with each other the way people do in a square dance: namely, by approaching one’s partner, linking arms while skipping in a full circle ’dosey-doh,’ and then making a retreat. One tries to avoid the full-on collision to preserve the health of one’s partners. Stars interact similarly to well-trained square dancers, by exchanging momentum with the partner star. The two stars approach, describe a circular ‘dosey-doh,’ and then move away. Having said that, every so often two stars find themselves on a path to a direct collision. This event is so unlikely, and so short-lived, that astronomers do not often get the opportunity to see it. One of the best chances to look for such an unfortunate activity is in stellar nurseries called molecular clouds. This is because stars are born … Continue reading

Punting Black Holes
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As summer approaches, we can see examples of punting in more than just local playing fields. In addition to balls being punted halfway across a field, it looks more and more like 6 billion solar mass black holes can also be punted to vast distances across a galaxy. Now black holes are, as the name implies, completely black. The good news is that they can be spotted anyway for the cases in which the surrounding gas or even stars get too close to the black hole and start funneling onto it. In such cases the black hole can become piercingly bright. In fact the black hole is so bright that there is too much glare to see the fainter galaxy underlying it. Recently, astronomers have found a way to block out this extra glare from the ultra-bright supermassive black hole. Somewhat surprisingly, in a couple of cases a considerable offset is measured in the center of the galaxy compared to … Continue reading

The Other Feynman
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We have all heard of Rychard Feynman, who was famous for doing fundamental work in the areas of particle physics and in quantum mechanics which led to a Nobel Prize in physics. What is perhaps less well-known is that he also had a sister who was a reknowned physicist. According to an article in Popular Science this month, Dr. Joan Feynman started her career in 1932 when she was 5 years old. At that time she was set to turn switches to help her brother Rychard Feynman do physics experiments in their backyard. As a teenager, she recalls being inspired by reading about the work of Cecilia Payne-Gaposhkin in an Astronomy textbook. As Joan put it, “When I came to page 407 it changed my life.” For it was at this time that she realized almost as if in a revelation that women can do science! Joan Feynman graduated from Oberlin College with a B. S. in physics in 1948. … Continue reading

Spring cleaning in the Early Universe
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This is yet another installment on dust. Thanks to observations with the mighty Atacama Large Millimeter/submillimeter Array, or ALMA, a radio telescope in Chile, we can now view this humble material at a distance of 13.2 billion light years away. This is interesting as we think the universe is only 13.7 billion years old. If we turn the clock all the way back to just before there were any stars, we would find a universe made up of hydrogen, helium, and the slightest amount of lithium. If we now fast-forward to the time when the stars turned on in the universe for the first time, we expect for many of them to make enormous amounts of carbon, silicon and aluminum which combine together with hydrogen to make dust. Yes, we think it is thanks to stars that we have any dust at all. What is missing is finding those (close to the) first stars in that (close to the) first … Continue reading

The Most Recent Chapter on the Hubble Constant
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Astronomers agree that the universe is expanding in all directions, a notion now called the “Hubble expansion” to refer discoverer Mr. Edwin Hubble. A useful analogy to understand the Hubble expansion is to draw dots onto a balloon to represent galaxies in the universe. As you blow up the balloon the dots expand away from each other. While there seems to be no way around a universal Hubble expansion, now there is controversy brewing regarding the exact value for this rate of expansion. What is at stake may be a tiny misunderstanding in how we make the measurements, or may be a signal of new physics. Oh, we all agree now on the approximate answer, that the space between galaxies grows such that for every 3.3 million light years a galaxy moves in distance away from us, the velocity of that distant galaxy becomes 70 km/s faster. Equivalently, in astronomer’s jargon we say that the rate of expansion (H0) equals … Continue reading

Learning from a Flashlight in the Sky
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While many of us are dazzled by the spectacular examples of galaxies each one with its own 10-100 billion stars, some of us choose instead to study the regions between the galaxies. There is a fair amount of hydrogen gas in this “intergalactic medium,” yet this gas typically is too faint to see directly in images. We are able to study this dim gas only by looking at how it affects the light coming from bright objects in the background called quasars. There are a great many bright quasars, or galaxies with extremely bright nuclei, in the universe. These quasars each produce a tremendous amount of light much like the welcome sight of a flashlight on an otherwise dark and deserted hiking trail. Indeed if you were to look at the flashlight of a distant hiker during an evening walk, you may see the flashlight seem to ‘flicker’ not because the battery was running out but rather as a result … Continue reading

Smile Black Hole – You’re on Camera (Part Two)
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Who wouldn’t dream of seeing a black hole up close (but not too close)? In this second article we will take a look at the advances in technology that allow us to view the black hole at the center of the Milky Way. First, we should understand the obstacles. As we are situated in a disk galaxy, there are large numbers of stars situated exactly in between us and the Galaxy’s center. This introduces a kind of ‘light pollution’ in the form of starlight which interferes with our ability to see faint emission emanating from the accretion disk surrounding the black hole. This is analogous to watching a friend holding a piercingly-bright flash light on a dark path. You see the flashlight but not the physical features of your friend who you know must be holding the light. By choosing the color The Milky Way’s central supermassive black hole carefully, we are able to view the black hole at a … Continue reading