Thursday, February 28, 2008

Star Formation













NGC 3603, contains various stages of star formation, molecular clouds at right are stellar nurseries.

NGC 602, ongoing star formation in a young cluster.

Corona Australis, contains the coronet cluster at its center, is one of the nearest and most active star forming regions.

LH 95, star formation region, taken in March 2006 by Hubble.

NASA, star and planet formation.

NGC 7000, star forming wall is lit and eroding by bright, young stars.

M101, spiral galaxy shows giant star forming regions.

NGC 4038 and NGC 4039, merging galaxies show vigorous star formation, also known as the "Antennae".

Wednesday, February 27, 2008

Astronomer Biography












Henry Norris Russell

Danielle McCoy
Mr. Percival
Astronomy Honors
27 Feb. 2008

Henry N. Russell
For many years, Henry N. Russell was the leading theoretical astronomer in America. He began his life in Oyster Bay, New York on October 25, 1877. He was the first of three sons born to Alexander Gatherer Russell, a liberal Presbyterian minister, and Eliza Hoxie Norris, a mathematically skilled mother. He began at Princeton Preparatory School in 1890 and Princeton University in 1893, from which he graduated in 1897 insigni cum laude. He mainly studied mathematics, but his professor, Charles A. Young, had a great astronomical influence on Henry. He spent a year at the University of Cambridge, in Cambridgeshire, England, as a special student, where he attended the lectures of George Darwin. He studied for two years at the Cambridge University Observatory, where he developed one of the first photographic parallax programs for determining distances to stars.

Henry later returned to Princeton in 1905 as an instructor. He spent most of his professional life at Princeton, quickly rising to professorship in 1911 and becoming director of the observatory in 1912. Henry was convinced that the future of astronomical practice did not lay in open-ended data gathering programs, but rather in problem-oriented research in which theory and observation worked together. He was free to search for any new and exciting problems and to apply his mathematical talents to find their solutions. Up until 1920, Henry’s interests ranged widely from planetary and stellar astronomy to astrophysics. He developed means for the analysis of the orbits of binary stars, and developed methods for calculating the masses and dimensions of eclipsing variable stars. He also developed statistical methods for estimating the distances, motions, and masses of groups of binary stars. Henry worked with observational astronomers to analyze their hard found data, and he frequently showcased this information.

In studying stellar parallax at Cambridge, Henry applied his study of binary stars to what they could show about the lives and evolutions of stars and stellar systems. He used his parallax measurements to determine the absolute brightness of stars. When he compared their brightness to their colors, he determined that the majority of the stars in the sky (dwarfs), blue stars are brighter than yellow stars and yellows brighter than reds, but a few stars (giants) did not follow the same relationship, the yellows and reds were exceptionally brighter. When he later plotted this data, plotting brightness and spectra in a diagram, he showed the relationship between a star’s true brightness and its spectrum. He announced his results in 1913, and discovered that a Danish astronomer, Ejnar Hertzsprung had made the same discoveries. Within a year, the diagram was published and came to be known as the Hertzsprung-Russell Diagram (HR Diagram).

Henry was a Christian liberal thinker; a family man, he married in 1908 and had four children with his wife. Being America’s leading astronomer, he was also president of the American Astronomical Society, the American Association for the Advancement of Science, and the American Philosophical Society. He received awards like, the gold medal of the Royal Astronomical Society of England, two medals of the French Academy, five medals of American scientific societies, and many honorary degrees. Mexico even bestowed on him the Order of the Aztec Eagle, and issued a postage stamp in his honor. He remained director of the Princeton Observatory until 1947, when one of his students succeeded him. He later died on February 18, 1957 in Princeton, New Jersey.

Works Cited
Evans, Jc. "Henry Norris Russell." Physics & Astro Dept. , George Mason U. 25 Feb. 2008 .
Tenn, Joseph. "Henry Norris Russell." The Bruce Medalists. 25 Feb. 2008 .


Tuesday, February 19, 2008

APOD 3.6

The Rosette Nebula, NGC 2237, is one of many cosmic clouds of gas and dust that resemble a flower, but this nebula is the one most often used for the image of Valentine's Day. This image includes a long stem of glowing hydrogen gas, which more reflects a long stem rose. Over 5,000 light-years away, located in Monoceros, the petals of this rose are a cosmic nursery, whose shape is sculpted by the winds and radiation coming from its central cluster of hot young stars. The stars in the cluster, known as NGC 2244, are only a few million years old, while the central cavity in the Rosette Nebula is approximately 50 light-years in diameter. This image is pretty amazing. It looks exactly like a rose, especially with the long stream of hydrogen gas appearing to come off of the rose itself, resembling the long stem of a rose. It is really amazing how the central cavity of the rosette nebula is over 50 lgiht-years in diameter, that's a big rose.

Thursday, February 7, 2008

APOD 3.5

NGC 4013, only about 50 million light-years away, can be seen in the constellation Ursa Major, and was originally thought to be a distant island universe. This spiral galaxy is especially known for its flattened disk shape and large amount of central stars with many dust lines. This image identifies a previously unknown object associated with NGC 4013, which is the enormous, faint loop which extends up and to the left, and is a mere 80 light-years from the galaxy's center. With further investigation, it appears that this faint loop is a stream of stars, originally belonging to another galaxy which was probably torn apart by gravitational tides as it merged with the larger spiral. Many astronomers believe this newly discovered tidal stream may explain the warped distribution of neutral hydrogen gas which has been seen in radio images of NGC 4013 and may even help explain the formation of our own Milky Way galaxy. This image is pretty amazing looking, and it is pretty cool to see the faint ring which is the stream of stars. To me, the stream of stars looks more like a stream of dust, but maybe that's just because this star stream is over 80 light-years away from a galaxy that is over 50 light-years away, which we all known is pretty far.

Friday, February 1, 2008

APOD 3.4

RCW 49, a dusty stellar star-forming region surrounds Westerlund 2, a young star cluster, in this skyscape shown beyond the visible spectrum of light. Shown in black and white, is the infrared data from the Spitzer Space Telescope, which compliment colors come from the Chandra X-ray image data (in false color) of the hot young stars in the cluster's central region. Near the southern constellation Centaurus, the cluster is situated at an estimated 20,000 light-years away. The square showing the Chandra field of view is about 50 light-years on a side. Westerlund 2 is only about 2 million years old, and contains some of our galaxy's most massive, luminous, and young stars. This is a pretty amazing picture with the 2 images placed together and shown in 2 different forms of light.