James Randi and Phil Plait. Credit: Bad Astronomy Blog
[/caption]
This news came out last week, but I’ve been out of town and now want to offer congratulations to the Bad Astronomer Phil Plait who is adding one more item to his long list of credientials and accomplishments. Phil will now be taking on the role of President….. of the James Randi Educational Foundation (JREF). If you’re not familiar with JREF, (you should be!), the goals of the Foundation are to bring critical thinking to the public, expose pseudoscientific frauds, and promote real science and rationality. If you’ve been reading Phil’s Bad Astronomy blog, you know that those are his goals as well, so this new role seems like a perfect fit for both Phil and JREF. Phil says he owes everything to Randi: “He opened my eyes – and my brain – to the idea that reality is a better place to live in than fantasy. I owe it all to Mr. Randi, so I am very excited and deeply honored to continue his vision with the JREF.”
Congrats Phil! We know you’ll “Phil” Randi’s shoes just fine. But you’ve got some work ahead of you on your beard….
Outgoing JREF President James Randi has long been known as a magician and escape artist, but he’s also a tireless investigator and demystifier of paranormal and pseudoscientific claims. Carl Sagan tells a great story about Randi in his book “The Demon Haunted World,” which highlights how gullible people can be and how easily people with paranormal claims can appear credible.
Randi has pursued “psychic” spoonbenders, exposed the dirty tricks of faith healers, and generally been a thorn in the sides of those who try to pull the wool over the public’s eyes in the name of the supernatural. Randi’s long-standing challenge for proof of claims of the paranormal now stands as a $1,000,000 prize that has yet gone unclaimed.
Phils says he would like to expand the efforts of JREF’s educational activities. “I want to teach kids about the wonders of the real Universe. We can do this by partnering with the educational community and developing fun, hands-on materials that schoolchildren can use in the classroom to teach them about critical thinking and the scientific method. Science is sometimes taught as being cold and dull, but nothing could be more wrong! It’s exciting, it’s fun, and it’s cool. Kids are natural scientists, and we need to encourage that, foster it, and let it grow.”
Globular clusters are gravitationally bound, dense concentrations of stars. There can be hundreds of thousands of stars in a cluster, and they are so close together that it’s hard to distinguish globular clusters outside of our galaxy from stars within our own galaxy just using ground-based telescopes: in other words, these big bunches of far away stars can look like a single, nearby star. But astronomers recently used the Hubble Space Telescope’s sharp eyes to identify, incredibly, over 11,000 globular clusters in the Virgo cluster of galaxies. And in doing so, they also noticed something interesting about where the globulars are located. Globular clusters don’t seem to form uniformly from galaxy to galaxy; instead they like to be where the action is near the center of galaxy clusters. The globulars are also more prevalent in dwarf galaxies near the center of the cluster of galaxies.
Hubble’s Advanced Camera for Surveys resolved the star clusters in 100 galaxies of various sizes, shapes, and brightnesses, even in faint, dwarf galaxies. Comprised of over 2,000 galaxies, the Virgo cluster is the nearest large galaxy cluster to Earth, located about 54 million light-years away.
Astronomers have long known that the giant elliptical galaxy at the cluster’s center, M87, hosts a larger-than-predicted population of globular star clusters. The origin of so many globulars has been a long-standing mystery.
“Our study shows that the efficiency of star cluster formation depends on the environment,” said Patrick Cote of the Herzberg Institute of Astrophysics in Victoria, British Columbia. “Dwarf galaxies closest to Virgo’s crowded center contained more globular clusters than those farther away.” M87 and Surrounding Galaxies in the Virgo Cluster. Credit: R. Gendler
The team found a bounty of globular clusters in most dwarf galaxies within 3 million light-years of the cluster’s center, where the giant elliptical galaxy M87 resides. The number of globulars in these dwarfs ranged from a few dozen to several dozen, but these numbers were surprisingly high for the low masses of the galaxies they inhabited. By contrast, dwarfs in the outskirts of the cluster had fewer globulars. Many of M87’s star clusters may have been snatched from smaller galaxies that ventured too close to it.
“We found few or no globular clusters in galaxies within 130,000 light-years from M87, suggesting the giant galaxy stripped the smaller ones of their star clusters,” explained Eric Peng of Peking University in Beijing, China, and lead author of the Hubble study. “These smaller galaxies are contributing to the buildup of M87.”
Hubble’s “eye” is so sharp that it was able to pick out the fuzzy globular clusters from stars in our galaxy and from faraway galaxies in the background. “With Hubble we were able to identify and study about 90 percent of the globular clusters in all our observed fields,” Peng said. “This was crucial for dwarf galaxies that have only a handful of star clusters.”
Evidence of M87’s galactic cannibalism comes from an analysis of the globular clusters’ composition. “In M87 there are three times as many globulars deficient in heavy elements, such as iron, than globulars rich in those elements,” Peng said. “This suggests that many of these ‘metal-poor’ star clusters may have been stolen from nearby dwarf galaxies, which also contain globulars deficient in heavy elements.”
Studying globular star clusters is critical to understanding the early, intense star-forming episodes that mark galaxy formation. They are known to reside in all but the faintest of galaxies.
“Star formation near the core of Virgo is very intense and occurs in a small volume over a short amount of time,” Peng noted. “It may be more rapid and more efficient than star formation in the outskirts. The high star-formation rate may be driven by the gravitational collapse of dark matter, an invisible form of matter, which is denser and collapses sooner near the cluster’s center. M87 sits at the center of a large concentration of dark matter, and all of these globulars near the center probably formed early in the history of the Virgo cluster.”
The fewer number of globular clusters in dwarf galaxies farther away from the center may be due to the masses of the star clusters that formed, Peng said. “Star formation farther away from the central region was not as robust, which may have produced only less massive star clusters that dissipated over time,” he explained.
Soil in Mars Arctic Region. Credit: NASA/JPL/Caltech/ U of Arizona
[/caption]
Scientists from the Phoenix lander are analyzing conflicting results from soil samples delivered to two science instruments on the Mars lander. Two different samples analyzed by the spacecraft’s Wet Chemistry Lab both suggested one of the soil constituents may be perchlorate, a highly oxidizing substance that is considered toxic. But results from the TEGA instrument, (Thermal and Evolved-Gas Analyzer) downloaded from the lander over the weekend indicated no evidence of perchlorate. These findings may may have prompted the reports of “provocative” science results recently. Today, Phoenix officials said any reports of the spacecraft finding life were unfounded, and over the weekend, the Phoenix spacecraft itself said, via Twitter, that reports of White House briefings were not true. NASA will hold a media teleconference on Tuesday, Aug. 5, at 2 p.m. EDT, to discuss the recent science activities. A press release from the Phoenix team today said, “Confirmation of the presence of perchlorate and supporting data is important prior to scientific peer review and subsequent public announcements.”
Scientists said that while the conflicting results are unexpected, they are working hard to understand the soil chemistry and mineralogy in the Mars northern arctic region.
“This is surprising since an earlier TEGA measurement of surface materials was consistent with but not conclusive of the presence of perchlorate,” said Peter Smith, Phoenix’s principal investigator at the University of Arizona, Tucson. “We are committed to following a rigorous scientific process. While we have not completed our process on these soil samples, we have very interesting intermediate results,” said Smith, “Initial MECA analyses suggested Earth-like soil. Further analysis has revealed un-Earthlike aspects of the soil chemistry.”
The team also is working to totally exonerate any possibility of the perchlorate readings being influenced by terrestrial sources which may have migrated from the spacecraft, either into samples or into the instrumentation. One type of perchlorate, ammonium perchlorate, is sometimes used as an oxidizer in rocket fuel.
“When surprising results are found, we want to review and assure our extensive pre-launch contamination control processes covered this potential,” said Barry Goldstein, Phoenix project manager at NASA’s Jet Propulsion Laboratory.
An article on AviationWeek.com reported August 1 that the US president had been briefed on findings from Phoenix, and NASA would be ready to reveal the findings in mid-August. An article on Universe Today was based on that report. Today, Aviation Week & Space Technology stands by its report, saying that “the new information involves the “potential for life” on Mars. That potential can either be positive or negative, and the new data indicate the new soil tests are at best inconclusive, according to the information being released on the soil chemistry experiment.”
Phoenix’s Wet Chemistry Lab is part of the Microscopy, Electrochemistry, and Conductivity Analyzer, or MECA instrument which studies soluble chemicals in the soil by mixing a soil sample with a water-based solution with several reagents brought from Earth. The inner surface of each cell’s beaker has 26 sensors that give information about the acidity or alkalinity and concentrations of elements such as chloride or perchlorate. The beaker also can detect concentrations of magnesium, calcium and potassium, which form salts that are soluble in water.
The TEGA instrument has tiny ovens that heat soil samples, and analyzers that “sniff” vapors released from substances in a sample.
[/caption]Summertime conjurs up great images of enjoying a double dip ice cream cone, and what more wonderful way to enjoy than with two flavors? Would you like to have some fun while the Moon waxes this coming week? Then invite someone along for the ride and let’s take a look at how differently people perceive stellar color!
Let’s begin with every one’s summer favorite – Beta Cygni (RA 19 30 43 Dec +27 57 34) – Albireo. This star is an easy and colorful split in both small telescopes and binoculars… Or is it? Well-noted for its color contrast, almost every person this author has shared the eyepiece with sees it differently. The primary star is often touted as a golden yellow and the secondary as blue…but, in whose eyes? While I perceive them as orange and almost purple, many folks have reported seeing no color at all, or radical differences between them,
Since my curiosity often runs high, I asked high noted astrophotographer, Dietmar Hager to photograph Albeiro to see what results he could capture on film. Without adding additional color correction, it appears to me to be near the orange and blue end of the spectrum. Now, let’s try a far less professional method and see what we come up with…
Cor Caroli - TammyAlthough it’s on the low side, try your luck with Alpha Canes Venaticorum (RA 12 56 01 Dec +38 19 06), which is better known as Cor Caroli. The “Heart of Charles” is about 130 light-years away and is an easy double for a small telescope and even binoculars. While many very noteworthy observers fail to see color in this pair, many of us can! Take a close look… Do you think the primary star is tinged a bit more on the yellow side, while the secondary is faintly blue? Sufficiently bright enough to be caught in the act with crude methods such as a camcorder or webcam, Cor Caroli is another piece of a very cool mystery…
Ras Algethi - Deitmar HagerNow move on to Alpha Herculis (RA 17 14 38 Dec +14 23 25) – Ras Algethi – and the last player in our double-dip game. While it’s a lot tougher to split, the suggestion that the M-type primary should be red to the sight isn’t always correct. Also usually noted as a colorful pair, the companion star is supposed to be quite green – a color sensed well by the dark-adapted human eye. Perhaps some of my observing companions haven’t been quite “human,” because most see it as a very pale blue. Me? I see red and green. It would seem the answers aren’t quite black and white.
So, what do all of these stars have in common? None of them are “normal.” The A component of Cor Caroli is a magnetic and spectroscopic variable which has periodic changes in its metallic absorption lines. It is the most blue at minimum. Both the A and B stars are enveloped in an intense magnetic field. Albireo’s primary star has a composite spectrum and is actually a binary – a K-type star with a spectroscopic B-type companion. The B component of Albireo is also odd – it shows strong hydrogen absorption lines. And what of Ras Algethi? Believe it or not, the red giant primary is a variable star which is shedding a huge envelope of a gas, engulfing its B companion in the process. A companion star which itself is a binary with a composite spectrum!
Take a look at all of these stars this week before the Moon obscures their position. Albireo is the “head” of Cygnus, and Cor Caroli is the bright star located about a fistwidth away from the last star in the handle of the Big Dipper (Ursa Major). However, Alpha Herculis (south of the “Keystone”) is much more difficult to find without a starchart. For simple instructions, start at Altair (the brightest star in Aquila) and look more than a handspan west/northwest for equally bright Alpha Ophiuchi that will appear alone in the field to the unaided eye. Ras Algethi will be about 2 or 3 fingerwidths to the northwest.
Have fun and enjoy all the flavors – and colors – of summer!
These awesome binary star images of Albireo and Ras Algethi were geneoursly supplied for our inspection by AORAIA member, Dietmar Hager. Thank you for sharing the telescope with us!
Answer: As you probably know, our Sun is just a star. It’s our closest, most familiar star, but it’s still just a star. With a great big Universe out there, populated with countless stars, astronomers have been able to see examples of stars in all shapes, sizes, metal content and ages.
According to their system of classification, the Sun is known as a yellow dwarf star. This group of stars are relatively small, containing between 80% and 100% the mass of the Sun. So the Sun is at the higher end of this group. The official designation is as a G V star.
Stars in the this classification have a surface temperature between 5,300 and 6,000 K, and fuse hydrogen into helium to generate their light. They generally last for 10 billion years.
But there’s more to this question, because G V Stars can experience several different stages. Some are newly forming, others are in their middle ages, and others are nearing the end of their lives.
Our Sun is right in the middle ages, in a time known as the main sequence. It has already lived for 4.3 billion years, and will likely last another 7 billion years or so. At that point, it will balloon into a red giant star, and eventually collapse down into a white dwarf.
The Sun also belongs to the Population I group of stars, which contain relatively large amounts of heavier elements. The first ever stars, made from pure hydrogen and helium are Population III. These exploded as supernovae, producing fusing the lighter elements into heavier and heavier elements. Our Sun, then, contains the metal from previous generations of stars that went supernova.
Some other examples of the yellow dwarf star group include Alpha Centauri, Tau Ceti and 51 Pegasi.
For the quick answer, the Sun is a Population I yellow dwarf star, in the main sequence. Why is the Sun yellow? It’s actually because of the Earth’s atmosphere. If you saw it from space, it would actually look white.
[/caption]Greetings, fellow SkyWatchers! Are you ready for today’s eclipse? Be sure to follow Ian’s earlier instructions this week and catch the action for yourself! When the Sun is gone at last, then let’s continue through the New Moon weekend with our globular cluster studies and we’ll take a look at some of the summer’s finest for both binoculars and telescopes. If you’re not afraid of the dark, then follow me…
Friday, August 1, 2008 – Mark your calendar! A total solar eclipse occurs today in northern Canada, the Arctic and Asia. Totality will begin at 09:21:07 UT in Canada, with the path crossing Greenland, the Arctic Ocean, Russia, and Mongolia – ending in China at 11:21:28 UT. Maximum occurs at 10:21:08 UT. For those not in the path, a partial eclipse will be visible over northeastern Canada, most of Asia and Europe, and the Middle East, between 08:04:07 UT and 12:38:28 UT. Be sure to consult with online sources such as Mr. Eclipse for accurate locations of the path of totality. And please…NEVER look at the Sun without taking proper precautions. Wishing you clear skies for this event!
Since tonight is also New Moon, let’s continue our exploration of summer’s globular clusters. These gravitationally bound concentrations of stars contain anywhere from ten thousand to one million members, and attain sizes of up to 200 light-years in diameter. At one time, these fantastic members of our galactic halo were believed to be round nebulae; perhaps the very first to be discovered was M22 in Sagittarius by Abraham Ihle in 1665. This particular globular is easily seen in even small binoculars and can be easily located just slightly more than two degrees northeast of the teapot’s lid, Lambda Sagittarii – Kaus Borealis (RA 18 36 24 Dec -23 54 12).
M22Ranking third amidst the 151 known globular clusters in total light, M22 is probably the nearest of these incredible systems to our Earth, with an approximate distance of 9,600 light-years. It is also one of the nearest globulars to the galactic plane. Since it resides less than a degree from the ecliptic, it often shares the same eyepiece field with a planet. At magnitude 6, the class VII M22 will begin to show individual stars to even modest instruments and will burst into stunning resolution for larger aperture. About a degree west-northwest, mid-sized telescopes and larger binoculars will capture the smaller 8th magnitude NGC 6642 (RA 18 31 54 Dec -23 28 34). At class V, this particular globular will show more concentration toward the core region than M22. Enjoy them both!
Saturday, August 2, 2008 – If you’re out tonight at sunset, be sure to watch the horizon in hopes of catching a glimpse of the very beginning of the Moon’s return. Both Regulus and Venus are nearby!
Tonight, let’s return again to look at two globular giants so we might compare roughly equal sizes, but not equal classes. To judge them fairly, you must use the same eyepiece. Start first by re-locating previous study M4. This is a class IX globular cluster. Notice the powder-like qualities. It might be heavily populated, but it is not dense. Now return to another previous study, M13, which is of class V. Most telescopes will achieve at least some resolution and show a distinct core region. It is the level of condensation that creates the different classes. Judging a globular’s concentration is no different from judging magnitudes, and simply takes practice.
M71Now try your hand at M55 (RA 19 39 59 Dec -30 57 43) along the bottom of the Sagittarius teapot – it’s a class XI. Although it is a full magnitude brighter than the class I cluster M75, can you tell the difference in concentration? For those with GoTo systems, take a quick hop through Ophiuchus and look at the difference between NGC 6356 (class II) and NGC 6426 (class IX). If you want to try one that science can’t even classify? Look no further than M71 in Sagitta (RA 19 53 46 Dec +18 46 42). It’s all a wonderful game and the most fun comes from learning!
Sunday, August 3 – For SkyWatchers tonight, be sure to catch the tender crescent Moon pairing with lovely Saturn just after sunset! Now, let’s return to earlier evening skies as we continue our studies with one of the globulars nearest to the galactic center – M14. Located about 16 degrees (less than a handspan) south of Alpha Ophiuchi (RA 17 37 36 Dec -03 14 45), this 9th magnitude, class VIII cluster can be spotted with larger binoculars, but will only be fully appreciated with the telescope.
M14When studied spectroscopically, globular clusters are found to be much lower in heavy element abundance than stars such as our own Sun. These earlier generation stars (Population II) began their formation during the birth of our galaxy, making globular clusters the oldest formations an amateur can study. Globulars are distributed in a spherical halo around the galaxy center. In contrast, stars in the disk are mostly much younger, their populations having gone through cycles of starbirth and supernovae, which in turn have enriched the heavy element concentration in nearby star forming clouds. Of course, as you may have guessed, M14 breaks the rules! It contains an unusually high number of variable stars – in excess of 70 – with many of them known to be the W Virginis type. In 1938, a nova appeared in M14, but it went undiscovered until 1964 when Amelia Wehlau of the University of Ontario was surveying the photographic plates taken by Helen Sawyer Hogg. The nova was revealed on eight of these plates taken on consecutive nights and showed itself as a 16th magnitude star – and at its peak was believed to be almost five times brighter than other cluster members. So unlike 80 years earlier with T Scorpii in M80, actual photographic evidence of this event existed. In 1991, the eyes of the Hubble were turned its way, but neither the suspect star nor traces of a nebulous remnant were discovered. But six years later, a rare carbon star was discovered in M14.
To a small telescope, M14 will offer little to no resolution and will appear almost like an elliptical galaxy, lacking any central condensation. Larger scopes will show hints of resolution, with a gradual fading toward the cluster’s slightly oblate edges. A true beauty!
This week’s awesome images are: Total Eclipse – Credit: NASA (Fred Espenak), M22 – Credit: N.A.Sharp, REU program/NOAO/AURA/NSF, M71 – REU program/NOAO/AURA/NSF and M14 – NOAO/AURA/NSF.
Artist concept of the first stars. Credit: Harvard Smithsonian CfA
[/caption]
What were the first stars like that formed shortly after the Big Bang? We don’t know much about the conditions of the early universe 13 billion years ago, but a new computer simulation provides the most detailed picture yet of the first stars and how they came into existence. The composition of the early universe was quite different from that of today, said Dr. Naoki Yoshida, Nagoya University in Nagoya, Japan and Dr. Lars Hernquist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA. An article that will be published to the August 1 journal Science describes their findings from the computer model that simulates the early days of the universe, the “cosmic dark ages,” where the physics governing the universe were somewhat simpler. The astronomers believe small, simple protostars formed, which eventually became massive, but short-lived stars.
According to their simulations, gravity acted on minute density variations in matter, gases, and the mysterious “dark matter” of the universe after the Big Bang in order to form the early stages of a star called a protostar. With a mass of just one percent of our Sun, Dr. Yoshida’s simulation also shows that the protostar would likely evolve into a massive star capable of synthesizing heavy elements, not just in later generations of stars, but soon after the Big Bang. These stars would have been up to one hundred times as massive as our Sun and would have burned for no more than one million years. “This general picture of star formation, and the ability to compare how stellar objects form in different time periods and regions of the universe, will eventually allow investigation in the origins of life and planets,” said Hernquist.
“The abundance of elements in the Universe has increased as stars have accumulated,” he says, “and the formation and destruction of stars continues to spread these elements further across the Universe. So when you think about it, all of the elements in our bodies originally formed from nuclear reactions in the centers of stars, long ago.”
The goal of their research is to be able to figure out how the primordial stars formed, as well as predicting the mass and properties of the first stars of the universe. The researchers hope to eventually extend this simulation to the point of nuclear reaction initiation – when a stellar object becomes a true star. But that’s the point where the physics becomes much more complicated, and the researchers say they’ll need more computational resources to simulate that process.
Pictures of all the objects in the Solar System. Image credit: NASA/JPL
3D Deep Space – this is one of the most popular Solar System screensavers out there. There are several separate versions, and you can buy a pack that contains all their different versions for about $50. There are demo versions of each product, but they’ve got nag screens and only work for a limited amount of time.
NASA’s Genesis Spacecraft – This screensaver comes from NASA and teaches you about the Genesis spacecraft, and shows the path it will take through the Solar System.
SOHO – NASA/ESA’s SOHO spacecraft captures images of the Sun. This screensaver lets you display the images on your computer desktop while you’re not using it. It works with PC, and they released a Mac version in 2008.
Now this is a cool project. You can buy a glow in the dark Solar System kit, and put the entire Solar System on your ceiling. When you turn off the lights, the Sun and the planets glow in the dark.
There are several sets available from Amazon.com.
One kit is called Planets and Supernova, and it comes with 100 small, medium and large glow in the dark stars. It also has 9 planets for the Solar System (sshh, somebody tell them that Pluto isn’t a planet anymore).
Another set contains just the glow in the dark planets themselves. It’s pretty inexpensive, just $3.95 for the set.
And if you want a 3-dimensional version, check out this set. It’s got all the planets as well as stars. The largest planet is 4″ across.
