Black Holes:

These objects are so massive and their gravitational forces so strong, that nothing - not even light - can escape. To verify whether an object truly classifies as a black hole, astronomers need to determine how quickly stars and debris orbit around the center of these objects. The light emitted by stars and gas orbiting around a black hole appears redder when moving away from us (red-shift) and bluer when coming toward us (blue-shift). By looking for this telltale Doppler shift, STIS has uncovered and weighed several dozen super massive black holes at the core of galaxies. To nail down the relationship between black hole mass and the properties of the host galaxies, more observations of both high- and low-mass black holes are needed.

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Stellar Flares

Flares are powerful explosions on the surfaces of many stars. When our own Sun flares, the episodes frequently disrupt communications, create power line surges and threaten space travelers. Astronomers don't understand the physics behind such violent eruptions, but by studying the events on other stars, they will begin to unlock some of their physical secrets.

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Stars

STIS can use its high sensitivity and spatial resolution (or ability to detect fine detail) to study stars. The Carina Nebula, located in our own galactic neighborhood, about 8000 light years from the sun, is home to a number of newly formed massive stars. Many of these stars are more than 50 times more massive than our own Sun. A unique star in this nebula is Eta Carinae. Massive stars have very short lifetimes, and the super massive Eta Carinae is in the final stages of its short life. Eventually, Eta Carinae will end its life as an enormous supernova; the lobes of gas and dust on either side of the star imply that its final fate may arrive soon. At the time it ceased operating, STIS was being used in a continuing survey of the gas and dust blown off by this highly unstable, massive binary star.

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Galaxies and the Evolution of the Universe

STIS can simultaneously record the spectra of over 500 distinct locations within an extended object such as a galaxy. This is a crucial tool for the efficient mapping of a complex environment. By taking spectral measurements of deuterium (heavy Hydrogen) and ordinary hydrogen in intergalactic clouds of gas, astronomers will be able to determine how the ratio of abundances of deuterium to ordinary hydrogen has changed from the time of the big bang to the present. This information indicates how much mass the universe contains. Knowing the mass of the universe will help astronomers determine whether the universe will continue to expand forever or will ultimately stop expanding and begin to collapse.

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Planets Around Other Stars

STIS spectra of the transiting star-planet system HD209458 resulted in transit light curves so precise that starlight absorption by the planet's atmosphere was detected, allowing the identification of several planetary atmospheric constituents, including hydrogen, oxygen and sodium - a first. Astronomers discovered the atmosphere by watching how starlight dimmed slightly when the planet crossed in front of its star, an event known as a transit. During the transit, a small amount of starlight passed through the planet's atmosphere on its way to Earth. Hubble's spectrograph collected the light and dispersed it into the colors of the spectrum, which yielded clues about the atmosphere's chemical makeup.

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Listing of Known Planetary Systems

Distribution of Matter

Emitting the energy of more than a trillion Suns, quasars can be used to probe the universe. As their light streams toward Earth, the radiation encounters intergalactic clouds and other matter. These encounters show up in the spectral lines, giving astronomers an idea of what exists in the vast expense of space separating us from the very distant quasar.

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More Resources on Cosmology