Solar system's Milky Way neighborhood gets more respect
"Our new evidence suggests that the Local Arm should appear as a prominent feature of the Milky Way," said Alberto Sanna, of the Max-Planck Institute for Radio Astronomy. Sanna and his colleagues presented their findings to the American Astronomical Society's meeting in Indianapolis, Indiana.
Determining the structure of our own Galaxy has been a longstanding problem for astronomers because we are inside it. In order to map the Milky Way, scientists need to accurately measure the distances to objects within the Galaxy. Measuring cosmic distances, however, also has been a difficult task, leading to large uncertainties. The result is that, while astronomers agree that our Galaxy has a spiral structure, there are disagreements on how many arms it has and on their specific locations.
To help resolve this problem, researchers turned to the VLBA and its ability to make the most accurate measurements of positions in the sky available to astronomers. The VLBA's capabilities allowed the astronomers to use a technique that yields accurate distance measurements unambiguously through simple trigonometry.
By observing objects when Earth is on opposite sides of its orbit around the Sun, astronomers can measure the subtle shift in the object's apparent position in the sky, compared to the background of more-distant objects. This effect is called parallax, and can be demonstrated by holding your finger close to your nose and alternately closing each eye.
The VLBA's ability to precisely measure very tiny shifts in apparent position allows scientists to use this trigonometric method to directly determine distances much farther from Earth than previously was possible.
The astronomers used this method to measure the distances to star-forming regions in the Milky Way where water and methanol molecules are boosting radio waves in the same fashion that a laser boosts light waves. These objects, called masers, are like lighthouses for the radio telescopes. The VLBA observations, carried out from 2008 to 2012, produced accurate distance measurements to the masers and also allowed the scientists to track their motion through space.
A striking result was an upgrade to the status of the Local Arm within which our Solar System resides. We are between two major spiral arms of the Galaxy, the Sagittarius Arm and the Perseus Arm. The Sagittarius Arm is closer to the Galactic center and the Perseus Arm is farther out in the Galaxy. The Local Arm previously was thought to be a minor structure, a "spur" between the two longer arms. Details of this finding were published in the Astrophysical Journal by Xu Ye and collaborators.
"Based on both the distances and the space motions we measured, our Local Arm is not a spur. It is a major structure, maybe a branch of the Perseus Arm, or possibly an independent arm segment," Sanna said.
The scientists also presented new details about the distribution of star formation in the Perseus Arm, and about the more-distant Outer Arm, which encompasses a warp in our Galaxy.
The new observations are part of an ongoing project called the Bar and Spiral Structure Legacy (BeSSeL) survey, a major effort to map the Milky Way using the VLBA. The acronym honors Friedrich Wilhelm Bessel, the German astronomer who made the first accurate measurement of a star's parallax in 1838.
The VLBA, dedicated in 1993, uses ten, 25-meter-diameter dish antennas distributed from Hawaii to St. Croix in the Caribbean. It is operated from the NRAO's Domenici Science Operations Center in Socorro, NM. All ten antennas work together as a single telescope with the greatest resolving power available to astronomy. This unique capability has produced landmark contributions to numerous scientific fields, ranging from Earth tectonics, climate research, and spacecraft navigation, to cosmology.
The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.
Welcome to SUV System Ltd!
SUV System Ltd is ISO 90012008 Certified electronics distributor with 10 years of experiences.
We have built up long term business relationship with about many companies which are stockers and authorized agents. we have a steady and reliable supply to meet customer's demands to the greatest extent .Confidently, we are able to lower your cost and support your business with our years of professional service.
SUV System Ltd is Electronic Components Distributor Supplies,Find Quality Electronic Components Supplies Products IC(Integrated Circuits),Connectors,Capacitor,Resistors,Diodes,Transistors,LED at Suvsystem.com. Sourcing Other Energy, Environment, Excess Inventory Products from Manufacturers and Suppliers at Suvsystem.com
Electronic Components distributor:http://www.suvsystem.com
Connectors Distributor:http://www.suvsystem.com/l/Connectors-1.html
IC Distributor:http://www.suvsystem.com/l/IC(Integrated-Circuits)-1.html
LED Distributor:http://www.suvsystem.com/l/LED-1.html
Capacitor Distributor:http://www.suvsystem.com/l/Capacitor-1.html
Transistor Distributor:http://www.suvsystem.com/l/Transistors-1.html
Resistor Distributor:http://www.suvsystem.com/l/Resistors-1.html
Diode Distributor:http://www.suvsystem.com/l/Diodes-1.html
SUV System Ltd insists on the managing faith ofsincereness,speciality,foresight, win-win,so we build up stable-relationship customers located all over the world, including the States, Europe, Argentina, UAE, Malaysia, Australia,and India etc
we are focus on the following fields,and hope we can help you.
CRCW08051K50JNEAIF CRCW08051K50JNEA CRCW08051K50FKTA CRCW08051K50FKEB CRCW08051K50FKEAHP CRCW08051K50FKEA CRCW08051K47FKTA CRCW08051K47FKEA CRCW08051K43FKTB CRCW08051K43FKTA CRCW08051K43FKEA CRCW08051K40FKTA CRCW08051K40FKEA CRCW08051K37FKTA CRCW08051K37FKEA CRCW08051K33FKTA CRCW08051K33FKEA CRCW08051M20JNTA CRCW08051M20JNEA CRCW08051M20FKEA CRCW08051M18FKTA CRCW08051M18FKEA CRCW08051M15FKEA CRCW08051M13FKEA CRCW08051M10JNTA CRCW08051M10JNEA CRCW08051M10FKTA CRCW08051M10FKEA CRCW08051M07FKEA CRCW08051M05FKTA CRCW08051M05FKEA CRCW08051M02FKTA CRCW08051M02FKEA CRCW08051M00JNTB CRCW08051M00JNTA CRCW08051M00JNEB CRCW08051M00JNEAHP CRCW08051M00JNEA CRCW08051M00FKTB CRCW08051M00FKTA
http://www.suvsystem.com/a/2082.aspx
