This week's installment is shifting a bit, moving to cover a week range of Sunday through Saturday in order to better conform to other publications. Because of this, some items from the previous week dated for October 21 are duplicated here for consistency.
APOPHIS, FUSE, LIGHT POLLUTION EFFECTS, AND BLACK HOLES
Asteroid Apophis Composition Identified
On October 9, MIT scientists announced they had for the first time determined the composition of an asteroid. The team was lead by Richard P. Binzel, professor of planetary sciences in the Department of Earth, Atmospheric, and Planetary Sciences (EAPS). Binzel worked with graduate students Cristina Thomas and Francesca DeMeo and others. Using the MIT Magellan telescope in Chile and NASA's Infrared Telescope Facility in Hawaii, the team has been learning as much as possible about asteroid 99942 Apophis and other asteroids. In their study, the team used both visible-light and infrared spectroscopy, which means it measured how an object reflects light of different wavelengths in order to determine the object's exact mineral constituents.
The team compared their observations with the many thousands of meteorites collected over the years and found that Apophis was a very good match for a rare meteorite type known as type LL chondrite. Type LL chondrites are low in metal content (about 2% metallic iron). The principle minerals are bronzite and olivine, but some oligoclase is also present. Type LL chondrites make up only 7.2% of all reported meteorite falls. By relying on the laboratory measurements for density and strength of these meteorites, we can infer many of the same properties for Apophis. Binzel presented the new findings October 9 at the annual meeting of the Division for Planetary Sciences of the American Astronomical Society.
Asteroid 99942 Apophis was discovered in 2004. On April 13, 2029, Apophis will come very close to Earth, missing by 22,000 miles. When it returns in 2036, there is a very small possibility - about one chance in 45,000 - that it could strike the earth. An object the size of Apophis, approximately 270 meters across, could destroy an area as large as France, or produce tsunamis over a wide area if it struck at sea. Binzel’s team used Apophis as their first case study to determine the composition of a potentially hazardous asteroid in order better determine how to defend Earth. Their work is sponsored by NASA and the National Science Foundation.
To learn more about NASA’s Near-Earth Asteroid Program, visit: http://neo.jpl.nasa.gov/ and to learn more about MITs Department of Earth, Atmospheric, and Planetary Sciences, visit: http://eapsweb.mit.edu/
Pulling the Fuse on FUSE
This week, scientists and engineers said their formal goodbyes to NASA's Far Ultraviolet Spectroscopic Explorer (FUSE). Since its launch into high Earth orbit on June 24, 1999, FUSE has explored the Universe using the technique of high-resolution spectroscopy in the far-ultraviolet spectral region. As a spectroscopic telescope, FUSE broke starlight down into its constituent spectra, or wavelengths, so scientists could study the chemistry, velocity and temperature of objects and regions invisible to telescopes on the ground. For example, scientists used FUSE to confirm the existence of a halo of hot gas around the Milky Way galaxy -- the exhalations of exploding stars. FUSE also looked for molecular hydrogen on Mars, a remnant of the planet's vanished water.
The Johns Hopkins University (JHU) had the lead role in developing and operating the mission, in collaboration with The University of Colorado at Boulder, The University of California at Berkeley, international partners the Canadian Space Agency (CSA) and the French Space Agency (CNES), and corporate partners. Planning for FUSE began in the early 1980's and some team members have been working on the project since they were JHU graduate students.
FUSE was designed for a three-year mission, but has been running for eight. In that time the mission obtained over 130 million seconds (over 4 years, combined) of observing time. FUSE made observations of 2,800 celestial objects. Then on July 12, the last of the telescope's four troublesome "reaction wheels" ground to a stop, making it impossible to aim at stars and galaxies. Controllers had been creatively solving satellite problems for years in order to extend the mission, but this was the straw that broke the camel's back.
On Thursday, October 18, the FUSE mission terminated science operations and the satellite was shut down. The process was quite involved because the engineers had to overcome all of the safety protocols programmed into the satellite systems. Controllers will continue a near year-long process of monitoring the satellite in order to make sure it "stays dead," so that it will not interfere with any current or future missions that may share the same goals or communication frequencies, etc. By some estimates, FUSE may continue tumbling in orbit for up to 30 years before it re-enters the atmosphere.
To date, more than 1,200 scientific papers have been published with FUSE data, and many more are expected in the future. The mountain of FUSE data is being stored at the Multimission Archive at the Space Telescope Science Institute in Baltimore. The science archive will form the lasting legacy of the FUSE mission. No similar missions are currently planned, so this archive will have to suffice for astronomers for the foreseeable future. To learn more about the FUSE mission, check out the mission home page of the Far Ultraviolet Spectroscopic Explorer: http://fuse.pha.jhu.edu/
David Dunlap Observatory Soon to Go Dark
Thirty-five years ago, University of Toronto (U of T) astronomer Tom Bolton proved the existence of black holes. A few leading astrophysicists had predicted that so-called "black holes" could be created when huge stars die and implode under their own mass. According to theories, these super-dense objects would exert such a powerful gravitational pull that not even light could escape their grasp. Essentially, black holes would be invisible - and that would make it extremely difficult to find one.
Bolton, then 28, spent many long nights at the David Dunlap Observatory in Richmond Hill. He charted the strange movements of a star that appeared to be tugged by an unseen companion. Gases were being sucked off the surface of the star and disappearing into the void of space. He published his findings in 1972, arguing that the only logical explanation was a black hole.
The Dunlap Observatory is a facility of the Department of Astronomy and Astrophysics at the U of T. Opened in 1935, the observatory was a gift to the university by Jessie Dunlap as a memorial to her husband David Alexander Dunlap, who was a mining entrepreneur and astronomy buff. The observatory boasts the largest optical telescope in Canada, measuring 1.88 meters (74 inches) in diameter. At the time of its opening it was the second biggest in the world.
Unfortunately, the historic observatory has fallen victim to the urban sprawl around Toronto. Even with the electronic upgrades done in the 1980s, light pollution has limited the observable reach of the telescope. U of T representatives began considering the sale of the observatory and the surrounding 190-acre property, which had increase in value many times over since the original gift. Unfortunately, under the original terms of the Dunlap gift, the property would revert back to the family of it were no longer used for astronomy. University representative began extensive talks with the Dunlap family.
Finally, in September, U of T announced they would work with the Dunlap heirs to begin the process to establish the Dunlap Institute at U of T’s St. George campus. The institute is planned to be a world-class facility using. The institute will be funded by the Dunlap family through the sale of the existing Dunlap Observatory and the surrounding property. A large portion of the proceeds would be given to create the new Institute, while a smaller portion would be retained by the Dunlap descendants. The proposal for the project goes to the university’s governing council on October 30 for final approval.
The U of T astronomers admit that the old observatory is still useful for examining the stars in our own galactic neighborhood. However, they also explain that in order do groundbreaking the work that changes our understanding of the universe, they must observe the most distant objects. And in order to study the farthest and faintest objects, a bigger telescope in a darker location would be needed. By developing the telescopic equipment, the university hopes to be able to create an observatory powerful enough to look back to virtually the beginning of time.
To learn more about U of T’s David Dunlap Observatory and proposal for the Dunlap Institute, visit the observatory home page: http://www.astro.utoronto.ca/DOD/
Largest Known Stellar Back Hole To Date
Astronomers have located in the nearby galaxy M33 (3 million light years away) an exceptionally massive black hole in orbit around a huge companion star. By combining data from NASA's Chandra X-ray Observatory and the Gemini telescope on Mauna Kea, Hawaii, the mass of the black hole, known as M33 X-7, was determined to be 15.7 times that of the Sun, making M33 X-7 the most massive stellar black hole known. A stellar black hole is formed from the collapse of the core of a massive star at the end of its life. The details of the discovery were published in a paper that appears in the October 18 issue of the journal Nature.
The discovery raised lots of questions about how such a big black hole could have been formed. M33 X-7 orbits a companion star that eclipses the black hole every three and a half days. The companion star also has an unusually large mass, 70 times that of the Sun, making it the most massive companion star in a binary system containing a black hole. Astronomers expect that the companion star will also go supernova, resulting in a pair of black holes.
The properties of the M33 X-7 binary system - a massive black hole in a close orbit around a massive companion star - are difficult to explain using conventional models for the evolution of massive stars. The parent star for the black hole must have had a mass greater than the existing companion in order to have formed a black hole before the companion star.
Such a massive star would have had a radius larger than the present separation between the present star and black hole, so the two stars must have been brought closer while sharing a common outer atmosphere. This process typically results in a large amount of mass being lost from the system, so much that the parent star should not have been able to form a 15.7 solar-mass black hole.
The black hole's original star must have shed gas at a rate about 10 times less than predicted by models before it exploded. If even more massive stars also lose very little material, it could explain the incredibly luminous supernova seen recently as SN 2006gy. The star that created SN 2006gy is thought to have been about 150 times the mass of the Sun when it exploded. It suggests that massive stars use less of their mass toward the end of their lives than it was once thought. This would have a big effect on the black holes eventually created by these stars.
To learn more about the discovery, and about the Chandra X-Ray Observatory check out these websites: http://chandra.harvard.edu/ and http://chandra.nasa.gov/ and to learn more about the Gemini Observatory, check out: http://www.gemini.edu/
THE SKY THIS WEEK
Oct 21 - Peak of Orionid meteor shower. Observers under dark skies should see rates of 15 to 20 meteors per hour. The shower should also be strong a few days before and after the peak (about the 19th through the 23rd, called the maximum). This shower is caused by dust from Halley's Comet, which is also responsible for the Eta Aquarid Shower in the spring. Orionid meteors will appear to radiate from a point in the sky between the constellations Gemini and Orion, high in the southern sky. Meteors from the Orionid shower may be visible throughout the month of October and through the first week of November.
Meteors are best viewed from a dark-sky location. Observers in for the duration of the evening, or at least for several hours, should bring along a few things: a sleeping bag or blankets for warmth, a recliner or lawn chair, a hot beverage to help cut the chill, and binoculars to view the smoke trails of just-past meteors.
Oct 22 - Asteroid 2 Pallas is stationary. The body appears motionless in the sky due to the turning point between its direct and retrograde motion.
Oct 22 - Uranus is 1.8° south of Moon
Oct 23 - Mercury is in inferior conjunction
Oct 26, 12:52 AM - Full Moon, the Hunter’s Moon
Oct 26 - Moon at perigee, the point in the Moon's orbit when it is closest to Earth.
Oct 26 - Asteroid 48475 (1991 UD2) Occults HIP 13108, a 5.8 magnitude star
Oct 28 - Venus at its greatest western elongation (46°)
THIS WEEK IN HISTORY
Oct 25, 1877 - Henry Russell's 130th Birthday
Oct 21, 1897 - Opening of Yerkes Observatory (110th Birthday). Yerkes Observatory is a facility of the Department of Astronomy and Astrophysics of the University of Chicago. It was established in 1897 on Geneva Lake in Williams Bay, Wisconsin. Until the mid-1960's, Yerkes Observatory housed all of the Department's activities. Today the 77-acre, park-like site in southeast Wisconsin provides laboratory space and access to telescopes for research and instruction. The telescopes at Yerkes include the 40-inch (102 cm) refractor constructed by Alvan Clark and Sons (the largest refractor), a 40-inch (102 cm) reflector, a 24-inch (61 cm) reflector, a 10-inch (25 cm) Cassegrain reflector, and a 7-inch (18 cm) Schmidt camera. To learn more, visit the Yerkes Observatory public home page: http://astro.uchicago.edu/yerkes/
The Yerkes Observatory and its grounds are in serious danger of being sold by the University of Chicago to local developers. To learn what is being done to help save the Yerkes Observatory, and to learn how you can help, visit the organization website, Save Yerkes Observatory: http://www.saveyerkes.com/
"The Minstrel Boy" is an emotionally stirring and inspirational song. It was written by Thomas Moore (1779-1852) who set the words to the melody of an ancient Irish aire called "The Moreen." It is widely thought that Moore composed the song in remembrance of a number of his friends, whom he met while studying at Trinity College, Dublin and who had participated in the 1798 rebellion of the United Irishmen. As the story goes, one friend was wounded, another friend died in prison, and a third was captured and later hung. Yet through it all, Moore refused to testify against his friends.
The song gained widespread popularity and became a favorite of many of the Irish who fought during the United States Civil War. The third first of the song was added at that time by unknown authors.
The song is notably associated with many U.S. organizations that historically had large numbers of members of Irish descent. These organizations include various city police departments and fire departments. The melody is frequently played at funerals of members and/or officers of such organizations who have died or been killed in service, typically on bagpipes. The song is also associated with the Irish Army and with traditionally Irish regiments and/or Irish Brigades found in other armies.
This song is quite popular and has been heard in many movies, such as the 2001 film "Black Hawk Down," and in many television series. Fans of Star Trek may remember that the song's first verse was sung by the character Miles O'Brien (actor Colm Meaney) in the Star Trek: The Next Generation fourth-season episode entitled "The Wounded." During the run of the spin-off series Star Trek: Deep Space Nine the tune became an unofficial theme song for the O'Brien character, and can be heard in several episodes.
The Minstrel Boy
The Minstrel Boy to the war is gone
In the ranks of death you will find him;
His father's sword he hath girded on,
And his wild harp slung behind him;
"Land of Song!" said the warrior bard,
"Tho' all the world betrays thee,
One sword, at least, thy rights shall guard,
One faithful harp shall praise thee!"
The Minstrel fell! But the foeman's chain
Could not bring that proud soul under;
The harp he lov'd ne'er spoke again,
For he tore its chords asunder;
And said "No chains shall sully thee,
Thou soul of love and brav'ry!
Thy songs were made for the pure and free,
They shall never sound in slavery!"
The third verse, added during the 1860s:
The Minstrel Boy will return we pray
When we hear the news, we all will cheer it,
The minstrel boy will return one day,
Torn perhaps in body, not in spirit.
Then may he play on his harp in peace,
In a world such as Heaven intended,
For all the bitterness of man must cease,
And ev'ry battle must be ended.
To review the history, the text, or to listen to the melody, check out this page from the “Songs of Ireland” section of "Contemplations from the Marianas Trench - Music and Deep Thoughts" - http://www.contemplator.com/ireland/minstrel.html
To see a GIF image file of the score of the song, or to download an ABC file of the score, visit this page of "The Session" - http://www.thesession.org/tunes/display/6782
The following link has JPEG image files of an 1895 edition of the score, including a solo line and piano accompaniment. It is two pages in length and presents the first and second verses. The link is on the website called Library Ireland, a free online reference library of Irish material:http://www.libraryireland.com/Irish-Melodies/The-minstrel-boy-1.php