Astronomers have their eyes on a hot group of young stars, watching their every move like the paparazzi. A new infrared image from NASA’s Spitzer Space Telescope shows the bustling star-making colony of the Orion nebula, situated in the hunter’s sword of the famous constellation. Like Hollywood starlets, the cosmic orbs don’t always shine their brightest, but vary over time. Spitzer is watching the stellar show, helping scientists learn more about why the stars change, and to what degree planet formation might play a role.
“This is an exploratory project. Nobody has done this before at a wavelength sensitive to the heat from dust circling around so many stars,” said John Stauffer, the principal investigator of the research at NASA’s Spitzer Science Center, located at the California Institute of Technology in Pasadena. “We are seeing a lot of variation, which may be a result of clumps or warped structures in the planet-forming disks.”
The new image was taken after Spitzer ran out of its coolant in May 2009, beginning its extended “warm” mission. The coolant was needed to chill the instruments, but the two shortest-wavelength infrared channels still work normally at the new, warmer temperature of 30 Kelvin (minus 406 Fahrenheit). In this new phase of the mission, Spitzer is able to spend more time on projects that cover a lot of sky and require longer observation times.
One such project is the “Young Stellar Object ariability” program, in which Spitzer looks repeatedly at the same patch of the Orion nebula, monitoring the same set of about 1,500 variable stars over time. It has already taken about 80 pictures of the region over 40 days. A second set of observations will be made in fall 2010. The region’s twinkling stars are about one million years old – this might invoke thoughts of wrinkle cream to a movie star, but in the cosmos, it is quite young. Our middle-aged sun is 4.6 billion years old.
Young stars are fickle, with brightness levels that change more than those of adult, sun-like stars. They also spin around faster. One reason for the ups and downs in brightness is the existence of cold spots on their surfaces. Cold spots are the opposite of “age spots” – the younger the star, the more it has. The cold spots come and go as a star whips around, changing the amount of light that reaches our telescopes.
Tags: Orion nebula, Spitzer
Posted in Space Exploration, stars | 523 Comments »
Two University of Hawaii astronomers have found a binary star-disk system in which each star is surrounded by the kind of dust disk that is frequently the precursor of a planetary system. A binary star system consists of two stars bound together by gravity that orbit a common center of gravity. Most stars form as binaries, and if both stars are hospitable to planet formation, it increases the likelihood that scientists will discover Earth-like planets.
This binary system, 253-1536, stands out as the first known example of two optically visible stars, each surrounded by a disk with enough mass to form a planetary system like our own. It lies 1,300 light-years from Earth, in the famous Orion Nebula, the kind of rich cluster of stars that is a common birth environment for most stars in our Milky Way galaxy, including our Sun.
The two stars are 400 times farther from each other than Earth is from the Sun. They would take 4,500 years, or about the length of human recorded history, to complete one orbit around their common center. Both stars are only about a third the mass of our Sun and are much cooler and redder in color. Viewed from a potential future planet, the stellar neighbor would appear as an intense point in the night sky, about one thousand times brighter than the brightest star in our night sky, Sirius. Planets around the other star would be visible only through telescopes, but they would be within reach of spacecraft from a civilization with the same level of technology as ours.
The larger disk in 253-1536 is also the most massive found in the Orion Nebula so far. The discovery of this massive disk and the binary disk system improve our understanding of how common planet formation is in our Galaxy and place our Solar System in context.
Adapted from material taken from University of Hawaii news annoucement
Tags: M42, Orion nebula, proplyds
Posted in Constellations, Solar System, stars | 16 Comments »