Astronomy
Nearly one-third of the stars in our own galaxy have dramatically changed their orbits, say a team of researchers from the New Mexico State University who have created a new map of the Milky Way.
?In our modern world, many people move far away from their birthplaces, sometimes halfway around the world, now we're finding the same is true of stars in our galaxy ? about 30 percent of the stars in our galaxy have traveled a long way from where they were born,? said Michael Hayden, astronomy graduate student and lead author of the new study.
To build the new map of the Milky Way, the scientists used the Sloan Digital Sky Survey [SDSS] telescope's Apache Point Observatory Galactic Evolution Explorer [APOGEE] spectrograph to observe 100,000 stars during a 4 year period.
The key to creating and interpreting this map of the galaxy is measuring the elements in the atmosphere of each star. "From the chemical composition of a star, we can learn its ancestry and life history," Hayden said.
The chemical information comes from spectra, which are detailed measurements of how much light the star gives off at different wavelengths. Spectra show prominent lines that correspond to elements and compounds. Astronomers can tell what a star is made of by reading these spectral lines.
?Stellar spectra show us that the chemical makeup of our galaxy is constantly changing,? said Jon Holtzman, NMSU astronomy professor who was involved in the study. ?Stars create heavier elements in their cores, and when the stars die, those heavier elements go back into the gas from which the next stars form.?
As a result of this process of ?chemical enrichment,? each generation of stars has a higher percentage of heavier elements than the previous generation did. In some regions of the galaxy, star formation has proceeded more vigorously than in other regions ? and in these more vigorous regions, more generations of new stars have formed.
This means the average amount of heavier elements in stars varies among different parts of the galaxy. Astronomers then can determine what part of the galaxy a star was born in by tracing the amount of heavy elements in that star.
Hayden and his colleagues used APOGEE data to map the relative amounts of 15 separate elements, including carbon, silicon, and iron for stars all over the galaxy.
What they found surprised them, up to 30 percent of stars had compositions indicating that they were formed in parts of the galaxy far from their current positions.
When the team looked at the pattern of element abundances in detail, they found that much of the data could be explained by a model in which stars migrate radially, moving closer or farther from the galactic center with time. These random in-and-out motions are referred to as ?migration,? and are likely caused by irregularities in the galactic disk, such as the Milky Way?s famous spiral arms.
Evidence of stellar migration had previously been seen in stars near the sun, but the new study is the first clear evidence that migration occurs throughout the galaxy.
source:- newscenter.nmsu.edu
- Milkyway Galaxy
The Milky Way Galaxy, commonly referred to as just the Milky Way, or sometimes simply as the Galaxy, is the galaxy in which the Solar System is located. The Milky Way is a barred spiral galaxy that is part of the Local Group of galaxies. It is one of...
- Elliptical Galaxy
Elliptical Galaxy ...
- Types Of Galaxy
Spiral Galaxy ...
- Milky Way
Milky Way Facts It?s warped. The Milky Way is a disk about 120,000 light years across , with a central bulge that has a diameter...
- Galaxy
Picture Of The Day(Stars and Galaxies) Galaxy ...
Astronomy
One-third of Milky Way Stars have Changed their Orbits.
?In our modern world, many people move far away from their birthplaces, sometimes halfway around the world, now we're finding the same is true of stars in our galaxy ? about 30 percent of the stars in our galaxy have traveled a long way from where they were born,? said Michael Hayden, astronomy graduate student and lead author of the new study.
To build the new map of the Milky Way, the scientists used the Sloan Digital Sky Survey [SDSS] telescope's Apache Point Observatory Galactic Evolution Explorer [APOGEE] spectrograph to observe 100,000 stars during a 4 year period.
The key to creating and interpreting this map of the galaxy is measuring the elements in the atmosphere of each star. "From the chemical composition of a star, we can learn its ancestry and life history," Hayden said.
The chemical information comes from spectra, which are detailed measurements of how much light the star gives off at different wavelengths. Spectra show prominent lines that correspond to elements and compounds. Astronomers can tell what a star is made of by reading these spectral lines.
?Stellar spectra show us that the chemical makeup of our galaxy is constantly changing,? said Jon Holtzman, NMSU astronomy professor who was involved in the study. ?Stars create heavier elements in their cores, and when the stars die, those heavier elements go back into the gas from which the next stars form.?
As a result of this process of ?chemical enrichment,? each generation of stars has a higher percentage of heavier elements than the previous generation did. In some regions of the galaxy, star formation has proceeded more vigorously than in other regions ? and in these more vigorous regions, more generations of new stars have formed.
This means the average amount of heavier elements in stars varies among different parts of the galaxy. Astronomers then can determine what part of the galaxy a star was born in by tracing the amount of heavy elements in that star.
Hayden and his colleagues used APOGEE data to map the relative amounts of 15 separate elements, including carbon, silicon, and iron for stars all over the galaxy.
What they found surprised them, up to 30 percent of stars had compositions indicating that they were formed in parts of the galaxy far from their current positions.
When the team looked at the pattern of element abundances in detail, they found that much of the data could be explained by a model in which stars migrate radially, moving closer or farther from the galactic center with time. These random in-and-out motions are referred to as ?migration,? and are likely caused by irregularities in the galactic disk, such as the Milky Way?s famous spiral arms.
Evidence of stellar migration had previously been seen in stars near the sun, but the new study is the first clear evidence that migration occurs throughout the galaxy.
source:- newscenter.nmsu.edu
- Milkyway Galaxy
The Milky Way Galaxy, commonly referred to as just the Milky Way, or sometimes simply as the Galaxy, is the galaxy in which the Solar System is located. The Milky Way is a barred spiral galaxy that is part of the Local Group of galaxies. It is one of...
- Elliptical Galaxy
Elliptical Galaxy ...
- Types Of Galaxy
Spiral Galaxy ...
- Milky Way
Milky Way Facts It?s warped. The Milky Way is a disk about 120,000 light years across , with a central bulge that has a diameter...
- Galaxy
Picture Of The Day(Stars and Galaxies) Galaxy ...