Category: Astronomy

Exploring the cosmos

Mysterious G2 Cloud Near Black Hole Identified

W. M. Keck Observatory press release…

The mystery about a thin, bizarre object in the center of the Milky Way headed toward our galaxy’s enormous black hole has been solved by UCLA astronomers using the W. M. Keck Observatory, home of the two largest telescopes on Earth. The scientists studied the object, known as G2, during its closest approach to the black hole this summer, and found the black hole did not dine on it. The research is published today in the journal Astrophysical Journal Letters.

G2 at the galatic center
An image from W. M. Keck Observatory near infrared data shows that G2 survived its closest approach to the black hole. Credit Andrea Ghez/Gunther Witzel/UCLA Galactic Center Group/W. M. Keck Observatory
While some scientists believed the object was a cloud of hydrogen gas that would be torn apart in a fiery show, Ghez and her team proved it was much more interesting.

“G2 survived and continues happily on its orbit; a gas cloud would not do that,” said Andrea Ghez, UCLA professor of physics and astronomy who holds the Lauren B. Leichtman and Arthur E. Levine Chair in Astrophysics, and directs the UCLA Galactic Center Group. “G2 was completely unaffected by the black hole; no fireworks.”

Instead, the team has demonstrated it is a pair of binary stars that had been orbiting the black hole in tandem and merged together into an extremely large star, cloaked in gas and dust, and choreographed by the black hole’s powerful gravitational field.

“G2 is not alone,” said Ghez, who uses Keck Observatory to study thousands of stars in the neighborhood of the supermassive black hole. “We’re seeing a new class of stars near the black hole, and as a consequence of the black hole.”

Ghez and her colleagues — who include lead author Gunther Witzel, a UCLA postdoctoral scholar in Ghez’s research group, and Mark Morris, a UCLA professor of physics and astronomy — studied the event with both of the 10-meter telescopes at Keck Observatory.

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Mercury at Maximum Elongation

Today Mercury reaches maximum elongation, the furthest point it will reach from the Sun in the sky and the highest it will be above the sunrise for this morning apparition. The planet is easily visible as a bright, starlike object about 19° above the rising Sun as the twilight begins. Over the next couple weeks Mercury will slide back into the sunrise, heading for superior conjunction on December 7th.

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An Enormous Sunspot Complex

Sunspot complex AR2192 is the largest I have seen in a long time. Easily visible without a telescope, simply using appropriate eye protection. It is quite large, more than ten times the diameter of the Earth. There are reports of it being noticed at sunset.

I photographed the sunspot during lunch fron Waimea, setting up a little telescope next to my vehicle in the Keck parking lot. The photo was taken using a TV-76mm telescope, the EOS-M camera and a Baader solar film filter, the same setup I viewed the Venus transit with.

Of course there was a partial solar eclipse today, visible across western North America. Photos of this enormous sunspot and the eclipse are now being posted across the web. Unfortunately this eclipse was not visible from Hawai’i. If you have not taken a look, I urge you to step outside with your solar viewing glasses and take a quick look. You do have solar viewing glasses handy… Right?

Sunspot AR2192
Sunspot complex AR2192 on 23 October, 2014, Canon EOS-M and TV-76mm telescope

New Moon

Young Moon
A very young moon over Waikoloa, this is only 26 hours after new, visible to the unaided eye as a sliver in the fading glow of sunset
New Moon will occur today at 11:57HST.

A partial solar eclipse will sweep across western North America today, from Alaska to Mexico. For those in the best possible place the Moon will cover about 80% of the Sun. The eclipse will be visible for some distance out into the Pacific, but will not be visible in Hawai’i.

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Scientists Build First Map of Hidden Universe

W. M. Keck Observatory press release…

A team led by astronomers from the Max Planck Institute for Astronomy has created the first three-dimensional map of the ‘adolescent’ Universe, just 3 billion years after the Big Bang. This map, built from data collected from the W. M. Keck Observatory, is millions of light-years across and provides a tantalizing glimpse of large structures in the ‘cosmic web’ – the backbone of cosmic structure.

The Cosmic Web
3D map of the cosmic web at a distance of 10.8 billion light years. Credit: Casey Stark (UC Berkeley) AND Khee-Gan Lee (MPIA)
On the largest scales, matter in the Universe is arranged in a vast network of filamentary structures known as the ‘cosmic web’, its tangled strands spanning hundreds of millions of light-years. Dark matter, which emits no light, forms the backbone of this web, which is also suffused with primordial hydrogen gas left over from the Big Bang. Galaxies like our own Milky Way are embedded inside this web, but fill only a tiny fraction of its volume.

Now a team of astronomers led by Khee-Gan Lee, a post-doc at the Max Planck Institute for Astronomy, has created a map of hydrogen absorption revealing a three-dimensional section of the universe 11 billions light years away – the first time the cosmic web has been mapped at such a vast distance. Since observing to such immense distances is also looking back in time, the map reveals the early stages of cosmic structure formation when the Universe was only a quarter of its current age, during an era when the galaxies were undergoing a major ‘growth spurt’.

The map was created by using faint background galaxies as light sources, against which gas could be seen by the characteristic absorption features of hydrogen. The wavelengths of each hydrogen feature showed the presence of gas at a specific distance from us. Combining all of the measurements across the entire field of view allowed the team a tantalizing glimpse of giant filamentary structures extending across millions of light-years, and paves the way for more extensive studies that will reveal not only the structure of the cosmic web, but also details of its function – the ways that pristine gas is funneled along the web into galaxies, providing the raw material for the formation of galaxies, stars, and planets.

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The Moon and Jupiter

Tomorrow morning the Moon and Jupiter will be close. The Moon will rise first, followed by Jupiter at 01:34 to be almost 65° above the eastern horizon at sunrise. The Moon will be about 32% illuminated and about 6° above a bright Jupiter. The next day the Moon will have moved to the other side of Jupiter and be a bit further apart, about 10° separation.