Universe Today

September 28, 2011December 24, 2015 by Tammy Plotner

Bending The Rules – Exploring Gravitational Redshift

A cluster of galaxies as seen from the Hubble Space Telescope

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Hey. We’re all aware of Einstein’s theories and how gravity affects light. We know it was proved during a total solar eclipse, but what we’ve never realized in observational astronomy is that light just might get bent by other gravitational influences. If it can happen from something as small as a star, then what might occur if you had a huge group of stars? Like a galaxy… Or a group of galaxies!

What’s new in the world of light? Astrophysicists at the Dark Cosmology Centre at the Niels Bohr Institute have now gone around the bend and came up with a method of measuring how outgoing light is affected by the gravity of galaxy clusters. Not only does each individual star and each individual galaxy possess its own gravity, but a galaxy group is held together by gravitational attraction as well. Sure, it stands to reason that gravity is affecting what we see – but there’s even more to it. Redshift…

“It is really wonderful. We live in an era with the technological ability to actually measure such phenomena as cosmological gravitational redshift”, says astrophysicist Radek Wojtak, Dark Cosmology Centre under the Niels Bohr Institute at the University of Copenhagen.

Together with team members Steen Hansen and Jens Hjorth, Wojtak has been collecting light data and measurements from 8,000 galaxy clusters. Their studies have included calculations from mid-placed members to calibrations on those that reside at the periphery.

“We could measure small differences in the redshift of the galaxies and see that the light from galaxies in the middle of a cluster had to ‘crawl’ out through the gravitational field, while it was easier for the light from the outlying galaxies to emerge”, explains Radek Wojtak.

The next step in the equation is to measure the entire galaxy cluster’s total mass to arrive at its gravitational potential. Then, using the general theory of relativity, the gravitational redshift could be determined by galaxy location.

“It turned out that the theoretical calculations of the gravitational redshift based on the general theory of relativity was in complete agreement with the astronomical observations.” explains Wojtak. “Our analysis of observations of galaxy clusters show that the redshift of the light is proportionally offset in relation to the gravitational influence from the galaxy cluster’s gravity. In that way our observations confirm the theory of relativity.”

Of course, this kind of revelation also has other implications… theoretical dark matter just might play a role in gravitational redshift, too. And don’t forget dark energy. All these hypothetical models need to be taken into account. But, for now, we’re looking at the big picture in a different way.

“Now the general theory of relativity has been tested on a cosmological scale and this confirms that the general theory of relativity works and that means that there is a strong indication for the presence of dark energy”, explains Radek Wojtak.

As Walt Whitman once said, “I open the scuttle at night and see the far-sprinkled systems, And all I see multiplied as high as I can cypher edge but the rim of the farther systems. Wider and wider they spread, expanding, always expanding,Outward and outward and forever outward.”

Original Story Source: EurekAlert News Release. Link to Gravitational redshift of galaxies in clusters as predicted by general relativity.

September 28, 2011December 29, 2015 by Nancy Atkinson

Carnival of Space #216

A brand new Carnival of Space is hosted by Amy Teitel over at Vintage Space.

Click here to read Carnival of Space #216.

And if you’re interested in looking back, here’s an archive to all the past Carnivals of Space. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. And if you really want to help out, sign up to be a host. Send an email to the above address to join in.

September 28, 2011April 8, 2018 by Nancy Atkinson

Timelapse: Aurora Borealis in Finnish Lapland

This timelapse is a selection of northern lights filmed by Flatlight Films during the winter of 2011 in several locations in the Finnish Lapland. Sit back and enjoy from the warmth of your home or office!

September 28, 2011March 25, 2012 by Fraser Cain

Google+ Space Bloggers

I’ve decided I’m going to be the official curator for the list of space bloggers/reporters/researchers on Google+. My current list only contains about 35 people, so it’s missing lots of people. Tyson? Cox? If you’re not on Google+, I can’t get you on the list. And Google+ is free for anyone to join.

So, if you’re a space blogger, and you’re not on Google+, take a second, register and then email me or somehow communicate that you’re on Google+.

If you’re a writer for Universe Today and you’re not on Google+. I’m at a loss for words. 😉

I’m sharing this list every week or so with the people who have me circled, and people are reporting hundreds of new followers every time I share it.

Here’s my Google+ profile. And here’s a link to my recent share of space bloggers.

Did I mention we record every episode of Astronomy Cast as a Google+ hangout? so you can watch us record, ask us questions, and even correct our stupid mistakes, live as we record.

September 28, 2011December 24, 2015 by Nancy Atkinson

Red Alert! Space Station Aurora

Astronauts on the International Space Station had this view of the aurora on September 26, 2011. Credit: NASA

Astronauts had this view of the aurora on September 26, 2011. Credit: NASA

We’ve had some great views of the aurora submitted by readers this week, but this one taken from the International Space Station especially highlights the red color seen by many Earth-bound skywatchers, too. Karen Fox from the Goddard Space Flight Center says the colors of the aurora depend on which atoms are being excited by the solar storm. In most cases, the light comes when a charged particle sweeps in from the solar wind and collides with an oxygen atom in Earth’s atmosphere. This produces a green photon, so most aurora appear green. However, lower-energy oxygen collisions as well as collisions with nitrogen atoms can produce red photons — so sometimes aurora also show a red band as seen here.

Source: Goddard Space Flight Center Flickr

September 28, 2011December 24, 2015 by Nancy Atkinson

Sunny Side Up: New Image of the Fried Egg Nebula Reveals a Rare Yellow Hypergiant Star

An image from the Very Large Telescope of IRAS 17163-3907, which has a huge dusty double shell surrounding the central hypergiant star. The star and its shells resemble an egg white around a yolky centre, leading astronomers to nickname the object the Fried Egg Nebula. Credit: ESO/E. Lagadec

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A new look at the Fried Egg Nebula has revealed one of the rarest classes of stars in the Universe, a yellow hypergiant. This “sunny-side-up” view shows for the first time a huge dusty double shell surrounding this huge star.

“This object was known to glow brightly in the infrared but, surprisingly, nobody had identified it as a yellow hypergiant before,” said Eric Lagadec from the European Southern Observatory, who led the team that produced the new images.

And there’s good reason to keep an eye on this star: it will likely soon die an explosive death, and will be one of the next supernova explosions in our galaxy.

The monster star, IRAS 17163-3907 has a diameter about a thousand times bigger than our Sun. At a distance of about 13,000 light-years from Earth, it is the closest yellow hypergiant found to date and new observations show it shines some 500,000 times more brightly than the Sun. The total mass of this star is estimated to be roughly twenty times that of the Sun.

The star and its shells resemble an egg white around a yolky center, hence, the nickname of the Fried Egg Nebula – which is much easier to say than IRAS 17163-3907.

The observations of the star and the discovery of its surrounding shells were made using the VISIR infrared camera on the VLT. The pictures are the first of this object to clearly show the material around it and reveal two almost perfectly spherical shells.

Astronomers say that if the Fried Egg Nebula were placed in the center of the Solar System, Earth would lie deep within the star itself and the planet Jupiter would be orbiting just above its surface. The much larger surrounding nebula would engulf all the planets and dwarf planets and even some of the comets that orbit far beyond the orbit of Neptune. The outer shell has a radius of 10,000 times the distance from the Earth to the Sun.

Yellow hypergiants are in an extremely active phase of their evolution, undergoing a series of explosive events — this star has ejected four times the mass of the Sun in just a few hundred years. The material flung out during these bursts has formed the extensive double shell of the nebula, which is made of dust rich in silicates and mixed with gas.

Source: ESO

September 27, 2011December 24, 2015 by Ray Sanders

How Common are Terrestrial, Habitable Planets Around Sun-Like Stars?

Artst concept of the Kepler telescope in orbit. Credit: NASA

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Once again news from the Kepler mission is making the rounds, this time with a research paper outlining a theory that Earth-like planets may be more common around class F, G and K stars than originally expected.

In the standard stellar classification scheme, these type of stars are similar or somewhat similar to our own Sun (which is a Class G star); Class F stars are hotter and brighter and Class K stars are cooler and dimmer. Given this range of stars, the habitable zones vary with different stars. Some habitable planets could orbit their host star at twice the distance Earth orbits our Sun or in the case of a dim star, less than Mercury’s orbit.

How does this recent research show that small, rocky, worlds may be more common that originally thought?

Dr. Wesley Traub, Chief Scientist with NASA’s Exoplanet Exploration Program outlines his theory in a recent paper submitted to the Astrophysical Journal.

A possible habitable world? Credit: NASA/JPL

Based on Traub’s calculations in his paper, he formulates that roughly one-third of class F, G, and K stars should have at least one terrestrial, habitable-zone planet. Traub bases his assertions on data from the first 136 days of Kepler’s mission.

Initially starting with 1,235 exoplanet candidates, Traub narrowed the list down to 159 exoplanets orbiting F class stars, 475 orbiting G class stars, and 325 orbiting K class stars – giving a total of 959 exoplanets in his model. For the purposes of Traub’s model, he defines terrestrial planets as those with a radius of between half and twice that of Earth. The mass ranges specified in the model work out to between one-tenth Earth’s mass and ten times Earth’s mass – basically objects ranging from Mars-sized to the theoretical super-Earth class.

The paper specifies three different ranges for the habitable zone: A “wide” habitable zone (HZ) from 0.72 to 2.00 AU, a more restrictive HZ from 0.80 to 1.80 AU, and a narrow/conservative HZ of 0.95 to 1.67 AU.

After working through the necessary math of his model, and coming up with a “power law” that gives a habitable zone to a star depending on its class and then working out how many planets ought to be at those distances, Traub estimated the frequency of terrestrial, habitable-zone planets around Sun-like (Classes F, G and K) stars at (34 ± 14)%.

He added that mid-size terrestrial planets are just as likely to be found around faint stars and bright ones, even though fewer small planets show up around faint stars. But that is likely because of the limits of our currently technology, where small planets are more difficult for Kepler to see, and it’s easier for Kepler to see planets that orbit closer to their stars.

Traub discussed how the quoted uncertainty is the formal error in projecting the numbers of short-period planets, and that the true uncertainty will remain unknown until Kepler observations of orbital periods in the 1,000-day range become available.

Check out our previous coverage of exoplanet detections using the Kepler data at: http://www.universetoday.com/89120/big-find-citizen-scientists-discover-two-extrasolar-planets/

If you’d like to read Traub’s paper and follow the math involved in his analysis, you can do so at: http://arxiv.org/PS_cache/arxiv/pdf/1109/1109.4682v1.pdf

Learn more about the Kepler mission at: http://kepler.nasa.gov/

Source: arXiv:1109.4682v1 [astro-ph.EP]

September 27, 2011December 24, 2015 by VirtualAstro

An Easy Guide To Observing the Aurora

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With the recent solar activity and the high possibility of more coming up, here is an easy guide to observing the aurora. An aurora is a natural light display high in the Earth’s atmosphere, caused by energetic particles from the Sun, colliding with the Earth’s magnetic field.

These light displays are called the Aurora Borealis in the Northern hemisphere and Aurora Australis in the Southern hemisphere, but are commonly known as the Northern and Southern lights.

Viewing aurorae is incredibly simple, but the conditions need to be right for a display to appear.

Normally you can only see aurorae near the poles, such as in Canada, Iceland, and Norway or southern Australia and Antarctica, but when the Sun is highly active, more solar material is thrown in Earth’s direction, creating powerful geomagnetic storms. These storms can bring auroral displays further south to areas such as Southern UK and North to mid latitudes of the USA.

The intensity scale is known as the Planetary KP index and basically the higher the KP number the further south Aurorae can be seen, KP 8 or higher can be good for observers further south. To find out what current levels are check spaceweather.com or the Geophysical Institute at the University of Alaska Fairbanks

If aurora activity is predicted to be high and there is a possibility of seeing it at your location, try and find an area away from light pollution or bright lights and let your eyes adjust to the dark. This may require you to travel into the countryside to escape bright city light pollution.

The best time to spot aurora is around local midnight, but this can change depending on viewing conditions and the current intensity of the magnetic storm.

Once you are comfortable and your eyes have adjusted to the dark, face north (or south in the Southern Hemisphere).

You do not need binoculars, a telescope, or any other optical aid other than glasses if you wear them.

Look low and close to the horizon and look for the faint green/ reddish glow of aurora. It may be quite difficult to see at first, but if it is a powerful display it can be very easy to spot.

I live in the South of the UK and have seen the waving bands and curtain like structures quite easily in powerful geomagnetic storms.

If you have a camera that takes long exposures, use a tripod and try to image the aurora and send us your results.

Most of all, enjoy the show! Good luck!

Aurora September 26, 2011 From Acadia National Park Credit: hale_bopp37

Aurora Behind the Clouds Credit: Corinne Mills

September 27, 2011April 26, 2016 by Fraser Cain

Giveaway: Ankylosaur Attack by Daniel Loxton

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Daniel Loxton, the editor of Junior Skeptic magazine, has released a brand new children’s book called Ankylosaur Attack. This is Daniel’s second book, after his excellent Evolution: How We and All Living Things Came to Be (I’ve got this book and read it to my own kids).

To celebrate the release of Ankylosaur Attack, Daniel’s publisher has agreed to give away 5 copies of the book.

You know how this works, send an email to [email protected] with the subject “Loxton Book” before Friday, September 30th, 2011 at 12:00pm. We’ll choose 5 emails that we receive, totally at random, and the lucky winners a copy of the book.

While you’re at it, you should follow Daniel on twitter.

September 27, 2011December 24, 2015 by Nancy Atkinson

Active Sun, Beautiful Aurora: Reader Photos

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Readers have submitted some great images of aurorae taken last night (Sept. 26 or early morning of Sept. 27). Why all the auroral activity? Sunspot region 1302 is big and bad, spewing out some nasty stuff. NASA says the sunspot’s magnetic field is currently crackling with sub-X-class flares that could grow into larger eruptions as the sunspot continues to turn toward Earth.

Here are some reader photos of the sunspot and the aurorae it created. A stunning view from Karstad Sweden, from Flickr user Socrates 2013, is above.

Massive sunspot 1302 on Sept. 25, 2011, with an Earth inserted for size reference. Credit: Ron Cottrell

This massive sunspot region has already produced two X-flares (X1.4 on Sept. 22nd and X1.9 on Sept. 24th). The dark cores in the sunspots this image from reader Ron Cottrell is larger than Earth, (see inserted Earth for reference) and the entire active region stretches more than 100,000 km from end to end.

“Even with a small aperture, 40mm, Hydrogen – Alpha telescope the image details are amazing,” Cottrell emailed us. “I captured this image from my patio in Oro Valley, Arizona.” He used a webcam to do some image post processing.

Aurora on Sept. 26, 2011 at Porsgrunn, Norway. Credit: Kjetil Vinorum

Kjetil Vinorum sent us some aurora photos from Porsgrunn, Norway (59° 09′ 33.3″N, 9° 39′ 46.9″E) and says this is the first time he’s seen aurora so far south in a decade.

This all-sky time-lapse of the aurora on Sept. 26-27, 2011 is from Arne Danielsen of Vestby, Norway (N59°36’18” E10°45’40” A84m).
The video shows a total of 726 images, which were obtained from Sunset to Sunrise. North is up and West is right. Be patient to see the aurora! Via Cosmos4U on Twitter

The aurora over Vernon, British Columbia Canada, sent to us by UT reader Marcel.

This beautiful shot was taken on the evening of September 27, 2011 by Marcel in British Columbia, Canada. The view is overlooking an orchard in the Coldstream Municipality.

The H-Alpha Sunspot 1302 09-25-2011. Credit: John Chumack

Here’s another view of the active region 1302 from John Chumack of Galactic Images.

The region has unleashed M8.6 and M7.4 flares on Sept. 24 and an M8.8 flare early on Sept. 25. None of the blasts have been squarely Earth-directed, but this could change, NASA says, as the sunspot turns toward our planet in the days ahead. AR1302 is growing and shows no immediate signs of quieting down.

Aurora at 21:20 UTC on Sep. 26, 2011 from Königswinter, Germany. Credit: Daniel Fischer — Aurora at 21:20 UTC on Sep. 26, 2011 from Königswinter, Germany. Credit: Daniel Fische

This image from Monty Leventhal shows the sunspots in region 1302 spreading across the face of the Sun for approximately 186,000 km. He used a Canon 300D with an Hydrogen-alpha filter with a Meade S.C. 10 inch telescope.

More info on AR1302 from NASA