The constellation Cygnus, now visible in the western sky during twilight, hosts one of our galaxy's richest-known stellar construction zones. Astronomers viewing the region at visible wavelengths see only hints of this activity thanks to a veil of dust clouds forming "the Great Rift," a dark lane that splits the Milky Way.
Located in the vicinity of the second-magnitude star Gamma Cygni, the star-forming region was named Cygnus X when it was discovered as a diffuse radio source in the 1950s. Now, a study using data from NASA's Fermi Gamma-ray Space Telescope found that the tumult of star birth and death in Cygnus X has managed to corral fast-moving particles called cosmic rays.
Cosmic rays are subatomic particles (mostly protons) flying through the galaxy at nearly the speed of light, bouncing off electromagnetic fields in their path. However, when cosmic rays collide with interstellar gas, they produce gamma rays (the most energetic and penetrating form of light) that travel to us straight from the source. By tracing gamma-ray signals throughout the galaxy, Fermi's Large Area Telescope (LAT) is helping astronomers understand the sources of cosmic rays and how they're accelerated to such high speeds.
Cygnus X is estimated to have the raw materials to produce up to 2 million sun-like stars. This environment holds onto its cosmic rays despite their high energies by entangling them in turbulent magnetic fields created by the combined outflows of the region's numerous high-mass stars. This is providing astronomers with a new look at the early life of cosmic rays, before they long before they diffuse into the galaxy at large.
Bibliography:
www.sciencedaily.com
Monday, 28 November 2011
Sunday, 20 November 2011
Magnetic Fields Set Stage for Birth of New Stars
Astronomers have measured the alignment of magnetic fields in gigantic clouds of gas and dust in a distant galaxy. Their results suggest that such magnetic fields play a key role in channeling matter to form denser clouds, and thus in setting the stage for the birth of new stars.
Stars and their planets are born when giant clouds of interstellar gas and dust collapse.Astronomers know quite a bit about these so-called molecular clouds: They consist mainly of hydrogen molecules, which is unusual since conditions are rarely right for hydrogen atoms to bond in the cosmos. Astronomers then wondered how these clouds could come into being, and what makes matter congregate in regions a hundred or even a thousand times more dense than the surrounding interstellar gas? One theory suggests that galaxies' magnetic fields guide and direct the condensation of interstellar matter to form denser clouds and facilitate their further collapse. Astronomers Hua-bai Li and Thomas Henning from the Max Planck Institute for Astronomy chose the Triangulum galaxy, 3 million light-years from Earth and also known as M 33 to study to try and gain evidence of magnetic field influence. Li and Henning measured specific properties of radiation received from different regions of the galaxy which are correlated with the orientation of these region's magnetic fields. They found that the magnetic fields associated with the galaxy's six most massive giant molecular clouds were orderly, and well aligned with the galaxy's spiral arms. Their findings are a strong indication that magnetic fields do actually play an important role when it comes to the formation of dense molecular clouds; and to setting the stage for the birth of stars and planetary systems like our own.
Bibliography:
www.sciencedaily.com
Stars and their planets are born when giant clouds of interstellar gas and dust collapse.Astronomers know quite a bit about these so-called molecular clouds: They consist mainly of hydrogen molecules, which is unusual since conditions are rarely right for hydrogen atoms to bond in the cosmos. Astronomers then wondered how these clouds could come into being, and what makes matter congregate in regions a hundred or even a thousand times more dense than the surrounding interstellar gas? One theory suggests that galaxies' magnetic fields guide and direct the condensation of interstellar matter to form denser clouds and facilitate their further collapse. Astronomers Hua-bai Li and Thomas Henning from the Max Planck Institute for Astronomy chose the Triangulum galaxy, 3 million light-years from Earth and also known as M 33 to study to try and gain evidence of magnetic field influence. Li and Henning measured specific properties of radiation received from different regions of the galaxy which are correlated with the orientation of these region's magnetic fields. They found that the magnetic fields associated with the galaxy's six most massive giant molecular clouds were orderly, and well aligned with the galaxy's spiral arms. Their findings are a strong indication that magnetic fields do actually play an important role when it comes to the formation of dense molecular clouds; and to setting the stage for the birth of stars and planetary systems like our own.
Bibliography:
www.sciencedaily.com
Galaxies Are the Ultimate Recyclers, NASA's Hubble Confirms
Galaxies have been "green" since the universe existed. They continuously recycle immense volumes of hydrogen gas and heavy elements to build successive generations of stars that stretch over billions of years. Their recycling allows them to maintain their star-forming abillity for over 10 billion years. However, galaxies that ignite a rapid firestorm of star birth can blow away their remaining "fuel," essentially turning off further star-creating activity.
This conclusion is based on a series of Hubble Space Telescope observations that flexed the special capabilities of its comparatively new Cosmic Origins Spectrograph (COS) to detect otherwise invisible mass in the halo of our Milky Way and a sample of more than 40 other galaxies. Data from large ground-based telescopes in Hawaii, Arizona, and Chile also contributed to the studies by measuring the properties of the galaxies.
Bibliography:
www.sciencedaily.com
This conclusion is based on a series of Hubble Space Telescope observations that flexed the special capabilities of its comparatively new Cosmic Origins Spectrograph (COS) to detect otherwise invisible mass in the halo of our Milky Way and a sample of more than 40 other galaxies. Data from large ground-based telescopes in Hawaii, Arizona, and Chile also contributed to the studies by measuring the properties of the galaxies.
Bibliography:
www.sciencedaily.com
Blue Supergiant Stars
Blue supergiants are supergiant stars (class I) of spectral type O. They are extremely hot and bright, with surface temperatures of between 20,000 - 50,000 degrees Celsius. The best known example is Rigel, the brightest star in the constellation of Orion. It has a mass of around 20 times that of the Sun and gives out more light than 60,000 suns added together.
Despite their rarity and short lives, blue supergiant stars are heavily represented among the stars visible to the naked eye due to their inherent brightness that trumps their scarcity. Due to core nuclear reactions being slightly slower, the star contracts and since very similar energy is coming from a much smaller area (photosphere) then the star's surface becomes much hotter.
Bibliography:
http://www.sciencedaily.com
Despite their rarity and short lives, blue supergiant stars are heavily represented among the stars visible to the naked eye due to their inherent brightness that trumps their scarcity. Due to core nuclear reactions being slightly slower, the star contracts and since very similar energy is coming from a much smaller area (photosphere) then the star's surface becomes much hotter.
Bibliography:
http://www.sciencedaily.com
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