Stars are born in giant clouds of gas and dust. Astronomers have studied two star clusters using NASA's Chandra X-ray Observatory and infrared telescopes. The composite image below shows one of the clusters, NGC 2024, which is found in the center of the Flame Nebula about 1,400 light years from Earth.
A study of NGC 2024 suggest that the stars on the outskirts of these clusters are older than those in the central regions. This is different from what the simplest idea of star formation predicts, where stars are born first in the center of a collapsing cloud of gas and dust when the density is large enough. When the scientists studied new data, they found that the opposite seems to be true. According to the new results, the stars at the center of NGC 2024 were about 200,000 years old while those on the outskirts were about 1.5 million years in age.
Explanations for the new findings can be grouped into three broad categories. The first is that star formation is continuing to occur in the inner regions. This could have happened because the gas in the outer regions of a star-forming cloud is thinner and more diffuse than in the inner regions. Over time, if the density falls below a threshold value where it can no longer collapse to form stars, star formation will cease in the outer regions, whereas stars will continue to form in the inner regions, leading to a concentration of younger stars there.
Another suggestion is that old stars have had more time to drift away from the center of the cluster, or be kicked outward by interactions with other stars. Finally, the observations could be explained if young stars are formed in massive filaments of gas that fall toward the center of the cluster.
CREDIT: NASA/CXC/PSU/K.Getman, E.Feigelson, M.Kuhn and the MYStIX team; NASA/JPL-Caltech
The image below shows the magnetic field of our Milky Way galaxy as seen by the Planck
satellite, a European Space Agency mission with significant NASA
contributions. This image was compiled from the first all-sky
observations of polarized light emitted by interstellar dust in the
Milky Way. Light can become polarized when it is emitted by or scatters
off dust and other surfaces; in this state, the electric and magnetic
fields of individual light waves are aligned parallel to each other.
CREDIT: ESA and the Planck Collaboration
The image below is one of the highest-resolution photos ever taken of the planet Mercury.
Many craters of varying degradation states are visible, as well as
gentle terrain undulations. The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation
are unraveling the history and evolution of the Solar System's
innermost planet. MESSENGER acquired over 150,000 images and extensive
other data sets. MESSENGER is capable of continuing orbital operations
until early 2015.
CREDIT: NASA/Johns Hopkins University Applied Physics Laboratory
and Carnegie Institution of Washington
NASA's Lunar Reconnaissance Orbiter captured the image on Feb. 1 with its wide-angle camera, depicting a colorized view of the Earth rising over the 112-mile-wide (180 kilometers) Rozhdestvenskiy crater.
CREDIT: NASA/Goddard/Arizona State University
The storms at Saturn's north pole is shown in the NASA image below.
CREDIT: NASA/JPL/Hubble
In the image below, NASA's Hubble Space Telescope has caught Jupiter's moon Ganymede playing a game of "peek-a-boo." In this crisp Hubble image, Ganymede is shown just before it ducks behind the giant planet.
CREDIT: NASA/JPL/Hubble
In the incredible image below, Saturn's auroras put on a dazzling display of light.
CREDIT: NASA/JPL/Hubble
The photo below shows a long filament of solar material that erupted from the Sun's surface in a coronal mass ejection, or CME, that traveled at over 900 miles per second. The CME did connect with Earth's magnetic environment, or magnetosphere, causing aurora to appear four nights later.
CREDIT: NASA/JPL/Hubble
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