APOD 4.1

APOD 4.1
                 Atlas V Launches MMS 

In the image above, an Atlas V rocket is seen lifting off carrying NASA's Magnetospheric Multiscale Mission into Earth's orbit 10 days ago. This rocket was sent up to study the magnetosphere that surrounds and protects the Earth. Rockets bound for space are now launched from somewhere on Earth about once a week.

APOD 3.8

APOD 3.8
                 Earth During a Total Eclipse of the Sun

During a total solar eclipse, Earth appears dark in the region where people see the eclipse (due to the shadow of the Moon - shadow spot moves on Earth's surface at nearly 2,000 kilometers per hour - darkening locations for only a few minutes each). The image show is the Earth during the total solar eclipse of 2006 March (from the International Space Station). Friday, another eclipse will take place, created another distorted shadow that will be over part of the north Atlantic Ocean.

Astronomy Terms

Astronomy Terms
                 
Nova (or a recoccuring nova): cataclysmic nuclear explosion on a white dwarf which causes a brightening of the star. Novae are thought to occur on the surface of a white dwarf in a binary system. If the two stars of the system are sufficiently near to one another, material can be pulled from the companion star's surface onto the white dwarf. A nova is caused by the accretion of hydrogen onto the surface of the star, commencing a runaway fusion reaction.

Supernova (Type I and Type II): explosion of a massive supergiant star. May shine w brightness of 10 billion suns. The total energy output may be 10⁴⁴ joules, as much as the total output of the sun during its 10 billion year lifetime. The likely scenario is thatfusion proceeds to build up a core of iron. The "iron group" of elements around mass number A=60 are the most tightly boundnuclei, so no more energy can be gotten from nuclear fusion.

Can be classified as Type I or Type II depending upon the shape of their light curves and the nature of their spectra.

 

Supernovae are classified as Type I if their light curves exhibit sharp maxima and then die away gradually. The maxima may be about 10 billion solar luminosities. Type II supernovae have less sharp peaks at maxima and peak at about 1 billion solar luminosities. They die away more sharply than the Type I. Type II supernovae are not observed to occur in elliptical galaxies, and are thought to occur in Population I type stars in the spiral arms of galaxies. Type I supernovae occur typically in elliptical galaxies, so they are probably Population II stars.

Photodisintegration: Occurs when a high-energy photon is absorbed by an atomic nucleus. The nucleus splits to form lighter elements, releasing a neutron, proton or alpha particle in the process. Photodisintegration in a core-collapse supernova undoes hundreds of thousands of years of nuclear fusion by splitting the iron nuclei into helium nuclei and neutrons.



Neutronization: A process by which, during the collapse of the core of a star, protons and electrons are forced together. The extremely high density of the core causes electrons to combine with protons, forms neutrons and neutrinos.


Chandrasekhar mass: Astrophysicist, Subrahmanyan Chandrasekhar, showed that it is impossible for a white dwarf star, which is supported solely by a degenerate gas of electrons, to be stable if its mass is greater than 1.44 times the mass of the Sun. If such a star does not completely exhaust its thermonuclear fuel, then this limiting mass may be slightly larger. All direct mass determinations of actual white dwarf stars have resulted in masses less than the Chandrasekhar limit. A star that ends its nuclear-burning lifetime with a mass greater than the Chandrasekhar limit must become either a neutron star or a black hole.


Stellar nucleosynthesis:  process by which the natural abundances of the chemical elements within stars vary due to nuclear fusion reactions in the cores and overlying mantles of stars. Core fusion increases the atomic weight of its gaseous elements, causing pressure loss and contraction accompanied by increase of temperature. Structural changes of the star (evolution) become necessary to stabilize it. The energy released from nuclear fusion reactions accounted for the longevity of the Sun as a source of heat and light. The fusion of nuclei in a star, starting from its initial hydrogen and helium abundance, provides that energy and synthesizes new nuclei as a byproduct of that fusion process.

Neutron capture:  nuclear reaction in which an atomic nucleus and one or more neutrons collide and merge to form a heavier nucleus. Neutron capture plays an important role in the cosmic nucleosynthesis of heavy elements. In stars it can proceed in two ways: as a rapid (r-process) or a slow process (s-process). Nuclei of masses greater than 56 cannot be formed by thermonuclear reactions (i.e. by nuclear fusion), but can be formed by neutron capture/

Neutron activation analysis: can be used to remotely detect the chemical composition of materials. This is because different elements release different characteristic radiation when they absorb neutrons. This makes it useful in many fields related to mineral exploration and security.

APOD 3.7

APOD 3.7
            Enhanced Color Caloris 

The image above shows the Caloris basin on Mercury and it is one of the solar system's largest impact basins (created during early history of the solar system by the impact of a large asteroid-sized body). The basin is about 1,500 kilometers and it is Mercury's youngest large impact basin. The image above has enhanced color and is created as a mosaic based on image data from the Mercury-orbiting MESSENGER spacecraft. In this picture, the orange is where lava once filled and the blue areas are part of the original basin. The orange splotches around the basin's perimeter are thought to be volcanic vents.

Dorothea Klumpke Roberts Biography

Dorothea Klumpke Roberts Biography

             

            Dorothea Klumpke (August 9, 1861-1942) was an astronomer born in San Franciso to a German immigrant father. John Gerald Klumpke and Dorothea Mathilda Tolle were her parents and she started her life with wealth due to her father's success as a real estate broker. She has four sisters and two brothers (one brother died as an infant). She was the first women to observe a Leonid Meteor Storm from above the Earth. She and her siblings started out at a school in San Fransico but around 1877, her parents moved them to Europe to seek a better education for their children. Dorothea Klumpke started out in music but switched to astronomy, and enrolled at the University of Paris where she got her Bachelor of Science degree in 1886. Later on, she won a post as attaché in the Paris Observatory where she worked with G. Bigourdan and Schulhof. After working with them, she worked with Paul and Prosper Henry on a new 34 cm refracting telescope that was created to take pictures of asteroids. She would measure star positions, reduce data, study meteorites and work on stellar spectra. In 1886, the Carte du Ciel project to create an atlas of the stars was started and April 1877, Klumpke became a linguist (translating papers into French) for the International Congress of Astronomers. By 1889, Klumpke became the first recipient of the Prix de Dames award from the Sociétié des Astronomique de France and by 1893, she was made an Officier d'Académe of the Paris Academy of Sciences (both of these experiences were firsts for women). By 1891, she became Director of the Bureau of Measurements at the Paris Observatory.

            In 1896, Klumpke went to go see the solar eclipse taking place in Norway August 9, 1896. This is where she met her future husband Dr. Isaac Roberts (who shared her love of astronomy). 1899, she was selected to be lofted in a balloon to observe the Leonid meteor shower; however, the shower did not appear well (only 15 Leonid meteors were spotted). Despite the Leonid meteor shower not being spectacular, she was still the first woman to make astronomical observations from a balloon. She left her post in 1901 to marry Isaac Roberts and move to a Sussex home. She completed the photography of 52 regions of the sky before moving back to Paris to stay with her mother and her sister Anna. There, she returned to the Paris Observatory to measure, reduce, and print the results of Issac's work. March 6th, 1925, Dr. Dorothea Klumpke officially joined the Eastbay Astronomical Society (EAS) as a paid member at Chabot Observatory (became first life member January 1928). Her donations to the EAS probably helped prevent them from going bankrupt. In 1932 she received the Hèléne-Paul Helbronner prize from the French Academy of Sciences for her work in publishing the atlases.
             On February 22, 1934, she was elected to be a Chevalier of the Legion d'Honneur. Shortly after the presentation as Chevalier of the Legion d'Honneur, she left France with Anna and moved to San Francisco once again. October 5, 1942, Klumpke passed away after many years of being ill.

Planetary Nebulae

Planetary Nebulae

1. Dumbbell Nebula

Object data:
-M27
-one of the most photographed planetary nebulae in the night sky
- in constellation Vulpecula
- Magnitude 7.4 (easy to find)
- about 1,200 light-years from Earth
- discovered on 12th July 1764 by Charles Messier
- first planetary nebula to be discovered
- size: angular diameter is 8.0x5.7 arc-minutes

2. Helix Nebula

Object Data:
- in constellation Aquarius
- Discovered by Karl Ludwig Harding, probably before 1824
- one of the closest planetary nebulae to the Earth
- about 215 parsecs or 700 light-years away
- pop culture refers to it as the "Eye of God" or the "Eye of Sauron"
- size: about 16 arc minutes diameter

3. Ring Nebula

Object Data:
- M57
- in constellation Lyra
- discovered by the French astronomer Antoine Darquier de Pellepoix in January 1779
- 0.7 kpc (2,300 light-years) from Earth
- Magnitude: 8.8
- size: 2.5 (arc minutes) in diameter (central bright ring)

4.  Cat's Eye Nebula

Object Data:
- bull's eye pattern of eleven or more concentric rings (shells)
- Each 'ring' is actually edge of a spherical bubble projected onto the sky
- in constellation Draco
- discovered by William Herschel on February 15, 1786.
- first planetary nebula whose spectrum was investigated by the English amateur astronomer William Huggins, demonstrating that planetary nebulae were gaseous and not stellar in nature.
-  magnitude of 8.1
- about three thousand light-years from Earth
- size: inner nebula subtends an average of 16.1 arcsec, with the outer prominent condensations about 25 arcsec

5. Eskimo Nebula

Object Data:
-  also known as Clownface Nebula or Caldwell 39
- discovered by astronomer William Herschel in 1787
-  more than 2,870 light-years away
- in constellation Gemini
- magnitude is 9
- size: 0.8 arcmins

6. The Glowing Eye Nebula

Object Data:
- in Constellation Aquila
- Distance: 6,500 light-years
- Size: 0.8 light-years
- Observed by Hubble in 1998

 7. NGC 6210

Object Data: 
- odd planetary nebula in the constellation Hercules
- Distance: 6,500 light-years
- Size: Unknown
-contains stars similar to our Sun, in their final stages, giving us insight to the fate of our Sun

8. The Red Spider Nebula

Object Data:
- Constellation: Sagittarius
- Distance: 3,000 light-years
- Size: Unknown
- contains one of the hottest stars in the Universe, and generates 100 billion kilometer high waves

 9. The Retina Nebula

Object Data:
- Constellation: Lupus
- Distance: 3,900 light-years
- Size: Unknown
- symmetrical nebula

10. The Spirograph Nebula

Object Data:
- Constellation: Lepus
- Distance: 2,000 light-years
- Size: 0.3 light-years
- Resembles a shape that could be made on a spirograph -a toy which produces geometric patterns