May 30

Faint Portraits of First Galaxies Shed Light on Cosmic Dawn: Scientific American

Hubble Ultra-Deep FieldThe Hubble Ultra-Deep Field shows galaxies as they were when the Universe was young. Those with the highest estimated redshifts (numbers and insets) were born more than 13 billion years ago, soon after the Big Bang.Image: NASA, ESA, R. Ellis (Caltech), UDF 2012 Team

For one sleepless week in early September 2009, Garth Illingworth and his team had the early Universe all to themselves. At NASA’s request, Illingworth, Rychard Bouwens and Pascal Oesch had just spent the previous week staring into their computer screens at the University of California, Santa Cruz, scanning through hundreds of black-and-white portraits of faint galaxies recorded in a multi-day time exposure by a newly installed infrared camera on the Hubble Space Telescope. NASA simply wanted the three astronomers to preview the images and make sure that the camera was working correctly, before the agency released the data more widely.

But Illingworth, Bouwens and Oesch were hoping that they would find more — that at least some of those smudges of light would prove to be among the first galaxies to form in the Universe, less than 1 billion years after the Big Bang. Even a faint glimpse of such objects could provide fresh insights into some of the biggest questions in cosmology, ranging from the nature of the first stars to the tumultuous beginnings of galaxy formation.

That week, the astronomers began to focus on two dozen tiny candidate images — each so dim and grainy that they might easily be noise in the camera’s digital sensors. But as their analysis proceeded, it became clear that these patches of light had the right color, appearing only in the camera’s reddest filters — exactly what would be expected of newborn galaxies seen at a very great distance and very high redshift. And when the three colleagues started digitally adding together exposures of each candidate, says Illingworth, “suddenly there they were” — fuzzy, but undeniable images of galaxies. “That week in September was one of the most exciting times of my career!”

via Faint Portraits of First Galaxies Shed Light on Cosmic Dawn: Scientific American.

May 27

NASA – Hubble reveals the Ring Nebula’s true shape

A core disc of dark, smokey blue crossed with wisps of violet and ringed with all the colors of the rainbow before exploding into shells of red gasses streaking out across the stars

In this composite image, visible-light observations by NASA’s Hubble Space Telescope are combined with infrared data from the ground-based Large Binocular Telescope in Arizona to assemble a dramatic view of the well-known Ring Nebula. Credit: NASA, ESA, C.R. Robert O’Dell (Vanderbilt University), G.J. Ferland (University of Kentucky), W.J. Henney and M. Peimbert (National Autonomous University of Mexico)Credit for Large Binocular Telescope data: David Thompson (University of Arizona) › Larger image

The Ring Nebula’s distinctive shape makes it a popular illustration for astronomy books. But new observations by NASA’s Hubble Space Telescope of the glowing gas shroud around an old, dying, sun-like star reveal a new twist.

“The nebula is not like a bagel, but rather, it’s like a jelly doughnut, because it’s filled with material in the middle,” said C. Robert O’Dell of Vanderbilt University in Nashville, Tenn. He leads a research team that used Hubble and several ground-based telescopes to obtain the best view yet of the iconic nebula. The images show a more complex structure than astronomers once thought and have allowed them to construct the most precise 3-D model of the nebula.

The Ring Nebula is about 2,000 light-years from Earth and measures roughly 1 light-year across. Located in the constellation Lyra, the nebula is a popular target for amateur astronomers.

Previous observations by several telescopes had detected the gaseous material in the ring’s central region. But the new view by Hubble’s sharp-eyed Wide Field Camera 3 shows the nebula’s structure in more detail. O’Dell’s team suggests the ring wraps around a blue, football-shaped structure. Each end of the structure protrudes out of opposite sides of the ring.

via NASA – Hubble reveals the Ring Nebula’s true shape.

May 24

Rare View of Ancient Galaxy Crash Revealed: Scientific American

A close-up view, with the merging galaxies circled. The red data show dust-enshrouded regions of star formation, while green and blue show carbon monoxide gas and starlight, respectively. The blue blobs outside of the circle are galaxies located much closer to us. Image: ESA/NASA/JPL-Caltech/UC Irvine/STScI/Keck/NRAO/SAO

Astronomers have caught two big ancient galaxies in the act of colliding, shedding new light on the role such megamergers played in galactic evolution during the universe’s youth.

The colossal smash up will eventually produce one giant elliptical galaxy, researchers said, suggesting that most such behemoths formed rapidly in this manner long ago, rather than growing slowly over time by gobbling up a series of relatively small galaxies.

“I think at least 90 percent of elliptical galaxies at this mass were formed through this channel,” study lead author Hai Fu, of the University of California, Irvine, told SPACE.com. [Photos of Great Galactic Crashes]

via Rare View of Ancient Galaxy Crash Revealed: Scientific American.