Astronomical

Major Merger

This Hubble image of NGC 4676, nickednamed “The Mice,” illustrates an ongoing major merger between two colliding galaxies of similar mass. The gravitational forces between the two galaxies have produced two long tails of gas and stars stretching away from the galaxies, as well as a bridge of stripped material between the galaxies. Credit: NASA, H. Ford (JHU), G. Illingworth (UCSC/LO), M.Clampin (STScI), G. Hartig (STScI), the ACS Science Team, and ESA

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Astronomical

Comparison of Massive Galaxies at Early Times vs. Today

Massive galaxies today are substantially larger and more bulgy than massive galaxies 10 billion years ago. The left column illustrates the difference in size by comparing a face-on view of the massive present-day elliptical galaxy (NGC 4472) to the Hubble NICMOS image of a face-on ultra-compact galaxy from 10 billion years ago. The right column highlights the disky nature of massive young galaxies by contrasting an edge-on view of a modern bulge-dominated spiral (NGC 4594, the Sombrero Galaxy) with the an edge-on view of a massive disky galaxy from 10 billion years ago. Credit: T.

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Astronomical

Dramatic Transformation of Massive Galaxies over 10 Billion Years

The most massive galaxies present two to three billion years after the Big Bang differ dramatically from today’s, when the universe is 13.7 billion years old. A remarkably high fraction of the massive young galaxies host disk components, making them look like thick pancakes. In contrast, today’s most massive galaxies (ellipticals and lenticulars) typically have large bulges, and are shaped like watermelons. Additionally, 40% of the young massive galaxies are ultra-compact, compared to less than 1% of their massive elliptical and lenticular descendants today. Credit: T. Weinzirl, S. Jogee (U.

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Astronomical

Christmas Burst

The merging of the helium and neutron star produces a broad torus, plus two jets aligned with the rotation axis of the system. The jets interact with the previously ejected torus causing the observed spectrum. (Credit: A. Simonnet, NASA, E/PO, Sonoma State University)

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Astronomical

Kepler-18

The top graphic shows the orbits of the three known planets orbiting Kepler-18 as compared to Mercury's orbit around the Sun. The bottom graphic shows the relative sizes of the Kepler-18 and its known planets to the Sun and Earth. Credit: Tim Jones/McDonald Obs./UT-Austin

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Astronomical

Binary White Dwarf

Two white dwarfs have been discovered on the brink of a merger. In just 900,000 years, material will start to stream from one star to the other, beginning the process that may end with a spectacular supernova explosion. Watching these stars fall in will allow astronomers to test Einstein's theory of general relativity as well as the origin of a special class of supernovae. Credit: David A. Aguilar (CfA)

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Astronomical

HBC 722

This composite image reveals the hidden power sources of this volatile star forming region. Blue represents starlight as seen by the UK Infrared Telescope (UKIRT), green is Herschel's view of the heated gas by ultraviolet radiation from protostars, and red is cooler gas seen by the Caltech Submillimeter Observatory. X marks the outburst, an area astronomers will keep an eye on. (Credit: J. Green, Univ. of Texas/ESA/UKIRT/CSO)

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Astronomical

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