Posted on by Nancy Atkinson

Dark Galaxies Found from the Early Universe

Caption: This deep image shows the region of the sky around the quasar HE0109-3518, near the center of the image. The energetic radiation of the quasar makes dark galaxies glow, helping astronomers to understand the obscure early stages of galaxy formation. Credit:ESO, Digitized Sky Survey 2 and S. Cantalupo (UCSC)


How do you find a dark galaxy? Shine some light on the subject. Dark galaxies — ancient galaxies that contain little to no stars — have been theorized to exist but have not been observed, until now. An international team of astronomers think they have detected these elusive objects by observing them glowing as they are illuminated by a quasar.

Dark galaxies are small, gas-rich galaxies in the early Universe that are very inefficient at forming stars. They are predicted by theories of galaxy formation and are thought to be the building blocks of today’s bright, star-filled galaxies. Astronomers think that they may have fed large galaxies with much of the gas that later formed into the stars that exist today.

Being essentially devoid of stars, these dark galaxies don’t emit much light, making them very hard to detect. For years astronomers have been trying to develop new techniques that could confirm the existence of these galaxies. Small absorption dips in the spectra of background sources of light have hinted at their existence. However, this new study marks the first time that such objects have been seen directly.

“Our approach to the problem of detecting a dark galaxy was simply to shine a bright light on it,” said Simon Lilly, from the Institute for Astronomy at ETH Zurich, Switzerland) co-author of a new paper published in the Monthly Notices of the Royal Astronomical Society. “We searched for the fluorescent glow of the gas in dark galaxies when they are illuminated by the ultraviolet light from a nearby and very bright quasar. The light from the quasar makes the dark galaxies light up in a process similar to how white clothes are illuminated by ultraviolet lamps in a night club.”

Fluorescence is the emission of light by a substance illuminated by a light source. Quasars are very bright, distant galaxies, and their brightness makes them powerful beacons that can help to illuminate the surrounding area, probing the era when the first stars and galaxies were forming out of primordial gas.

This video zooms into the region around the quasar, HE 0109-3518:

In order to detect the extremely faint fluorescent glow of these dark galaxies, the team used the Very Large Telescope (VLT), and took a series of very long exposures, mapping a region of the sky around the bright quasar HE 0109-3518. They looked for the ultraviolet light that is emitted by hydrogen gas when it is subjected to intense radiation.

The team detected almost 100 gaseous objects lying within a few million light-years of the quasar, and narrowed the possible dark galaxies down to 12 objects. The team says these are the most convincing identifications of dark galaxies in the early Universe to date.

“Our observations with the VLT have provided evidence for the existence of compact and isolated dark clouds,” said Sebastiano Cantalupo from the University of California, Santa Cruz, lead author of the paper. “With this study, we’ve made a crucial step towards revealing and understanding the obscure early stages of galaxy formation and how galaxies acquired their gas.”

The astronomers were also able to determine some of the properties of the dark galaxies, and estimate that the mass of the gas in them is about 1 billion times that of the Sun, typical for gas-rich, low-mass galaxies in the early Universe. They were also able to estimate that the star formation efficiency is suppressed by a factor of more than 100 relative to typical star-forming galaxies found at similar stage in cosmic history.

Read the team’s paper.

Source: ESO

Posted on by Jason Major

The Moon Is Toxic

As our closest neighbor in space, a time-capsule of planetary evolution and the only world outside of Earth that humans have stepped foot on, the Moon is an obvious and ever-present location for future exploration by humans. The research that can be done on the Moon — as well as from it — will be invaluable to science. But the only times humans have visited the Moon were during quick, dusty  jaunts on its surface, lasting only 2-3 days each before departing. Long-term human exposure to the lunar environment has never been studied in depth, and it’s quite possible that — in addition to the many inherent dangers of living and working in space — the Moon itself may be toxic to humans.

An international team of researchers has attempted to quantify the health dangers of the Moon — or at least its dust-filled regolith. In a paper titled “Toxicity of Lunar Dust” (D. Linnarsson et al.) the health hazards of the Moon’s fine, powdery dust — which plagued Apollo astronauts both in and out of their suits — are investigated in detail (or as best as they can be without actually being on the Moon with the ability to collect pristine samples.)

Within their research the team, which included physiologists, pharmacologists, radiologists and toxicologists from 5 countries, investigated some of the following potential health hazards of lunar dust:

Inhalation. By far the most harmful effects of lunar dust would come from inhalation of the particulates. Even though lunar explorers would be wearing protective gear, suit-bound dust can easily make its way back into living and working areas — as Apollo astronauts quickly discovered. Once inside the lungs the super-fine, sharp-edged lunar dust could cause a slew of health issues, affecting the respiratory and cardiovascular system and causing anything from airway inflammation to increased risks of various cancers. Like pollutants encountered on Earth, such as asbestos and volcanic ash, lunar dust particles are small enough to penetrate deep within lung tissues, and may be made even more dangerous by their long-term exposure to proton and UV radiation. In addition, the research suggests a microgravity environment may only serve to ease the transportation of dust particles throughout the lungs.

Skin Damage. Lunar regolith has been found to be very sharp-edged, mainly because it hasn’t undergone the same kind of erosive processes that soil on Earth has. Lunar soil particles are sometimes even coated in a glassy shell, the result of rock vaporization by meteorite impacts. Even the finer particles of dust — which constitute about 20% of returned lunar soil samples — are rather sharp, and as such pose a risk of skin irritation in instances of exposure. Of particular note by the research team is abrasive damage to the outer layer of skin at sites of “anatomical prominence”, i.e., fingers, knuckles, elbows, knees, etc.

“The dust was so abrasive that it actually wore through three layers of Kevlar-like material on Jack [Schmitt’s] boot.”

– Professor Larry Taylor, Director of the Planetary Geosciences Institute, University of Tennessee (2008)

Eye Damage. Needless to say, if particles can pose abrasive damage to human skin, similar danger to the eyes is also a concern. Whether lunar dust makes its way into the eye via airborne movement (again, much more of a concern in microgravity) or through direct contact from fingers or another dust-coated object, the result is the same: danger of abrasion. Having a scratched cornea is no fun, but if you’re busy working on the Moon at the time it could turn into a real emergency.

While the research behind the paper used data about airborne pollutants known to exist on Earth and simulated lunar dust particles, actual lunar dust is harder to test. The samples returned by the Apollo missions have not been kept in a true lunar-like environment — being removed from exposure to radiation and not stored in a vacuum, for instance — and as such may not accurately exhibit the properties of actual dust as it would be encountered on the Moon. The researchers conclude that only studies conducted on-site will fill the gaps in our knowledge of lunar dust toxicity. Still, the research is a step in the right direction as it looks to ensure a safe environment for future explorers on the Moon, our familiar — yet still alien — satellite world.

Read the team’s paper in full here.

“The Apollo astronauts reported undesirable effects affecting the skin, eyes and airways that could be related to exposure to the dust that had adhered to their space suits during their extravehicular activities and was subsequently brought into their spacecraft.”

– Dag Linnarsson, lead author, Toxicity of Lunar Dust

Top image: Apollo 16 astronaut Charlie Duke with a dust-coated LRV. Side image: a dusty Gene Cernan in the LM at the end of an Apollo 17 EVA. (NASA/JSC)

Posted on by Nancy Atkinson

Astrophotos: Monster Sunspot Evolution


Caption: A 5-day sequence of sunspot group AR1520. Credit: Shahrin Ahmad, Kuala Lumpur, Malaysia. Click to see a larger version.

There’s a monster sunspot making its way across the face of the Sun, and it’s captured the attention of several astrophotographers. This first image is from Shahrin Ahmad, who created a sequence of images as the sunspot moved to face towards Earth from the southeastern limb. He used a Skywatcher 120ED at F/15 (2X barlow) with a Baader Solar Filter and a IMG132E camera for his images.

AR1520 stretches more than 127,000 km (10 Earth diameters) from end to end, and the magnetic field of this enormous sunspot harbors energy for strong solar flares. NOAA forecasters estimate an 80% chance of M-flares and a 25% chance of X-flares during the next 24 hours, according to Spaceweather.com.

Here are some more looks at AR1520:


Caption: Closeup of monster sunspot AR1520. Credit: John Chumack.

One of our favorite astrophotographer, John Chumack, took this image of AR1520 in white light on July 8, 2012 using a Lunt Solar Herschel Solar Wedge filter, DMK 21AF04 Fire-wire Camera, 2x barlow, with 1/1000 second exposure. See more at his Flickr page, or his website, Galactic Images.


Caption: Sun and sunspots: Credit: Mike Black

Mike Black took this one on July 9, 2012

Gear: Canon 1D Mark IV + Canon 400mm f/2.8 + 2x Extender III. Baader solar film in front of lens. See more on Mike’s Flickr page.

Want to see a size comparison of AR1520? The mascot of the Solar Dynamics Observatory, Camilla the Rubber Chicken posted this comparison to Jupiter, the biggest planet in the solar system:


Caption: Size comparison of AR1520 to Jupiter. Credit: Camilla_SDO on Twitter.

Here’s a look at the previously active region on the Sun, which last week blasted out numerous M-class flares and at least one X.1-class flares, again a sequence of images from Shahrin Ahmad:

Caption: A 7-day sequence of sunspot AR1515. Credit: Shahrin Ahmad, Kuala Lumpur, Malaysia.

Thanks to everyone for sharing their images!

Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.

Posted on by Jason Major

Surprising Swirls Above Titan’s South Pole

View of Titan's South Pole, showing a vortex. Credit: NASA

Thanks to Cassini’s new vantage point granted by its inclined orbit researchers have gotten a new look at the south pole of Titan, Saturn’s largest moon. What they’ve recently discovered is a swirling vortex of gas forming over the moon’s pole, likely the result of the approach of winter on Titan’s southern hemisphere.

What we’re seeing here is thought to be an open cell convection process in Titan’s upper atmosphere. In open cells, air sinks in the center of the cell and rises at the edge, forming clouds at cell edges. However, because the scientists can’t see the layer underneath the layer visible in these new images, they don’t know what other mechanisms may be at work.

A stable atmospheric event that’s found here on Earth as well, open cell convection can be compared to the action of boiling water.

Titan has already been seen to have a thicker area of high-altitude haze over its north pole, and as autumn progresses toward winter in Titan’s south during the course of Saturn’s 29.7-year-long orbit this may very well be the beginnings of a southern polar hood.

An animation of this southern vortex can be found here.

“We suspect that this maelstrom, clearly forming now over the south pole and spinning more than forty times faster than the moon’s solid body, may be a harbinger of what will ultimately become a south polar hood as autumn there turns to winter.  Of course, only time will tell.”

– Carolyn Porco, Cassini Imaging Team Leader

Discoveries like this are prime examples of why it was so important for Cassini to have an extended, long-duration mission around Saturn, so that seasonal changes in the planet and moons could be closely observed. New seasons bring new surprises!

The southern vortex structure was also captured in raw images acquired by Cassini on June 28. A color-composite made from three of those raw images is below (the vortex can be seen at center just right of the terminator):

You can find more images from Cassini on the CICLOPS Imaging Team site.

Image credits: NASA/JPL/Space Science Institute. Bottom RGB composite by Jason Major.

Posted on by John Williams

Sifting Starlight, Finding New Worlds

These two images show HD 157728, a nearby star 1.5 times larger than the sun. The star is centered in both images, and its light has been mostly removed by an adaptive optics system and coronagraph belonging to Project 1640, which uses new technology on the Palomar Observatory’s 200-inch Hale telescope near San Diego, Calif., to spot planets. Credit: Project 1640

Looking directly at stars is a bad way to find planets orbiting faraway suns but using a new technique, scientists can now sift the starlight to find new exoplanets millions of times dimmer than their parent stars.

“We are blinded by this starlight,” says Ben R. Oppenheimer, a curator in the American Museum of Natural History’s Department of Astrophysics and principal investigator for Project 1640. “Once we can actually see these exoplanets, we can determine the colors they emit, the chemical compositions of their atmospheres, and even the physical characteristics of their surfaces. Ultimately, direct measurements, when conducted from space, can be used to better understand the origin of Earth and to look for signs of life in other worlds.”

Using indirect detection methods, astronomers have found hundreds of planets orbiting other stars. The light stars emit, however, is tens of millions to billions of times brighter than the light reflected by planets.

Project 1640 is an advanced telescope imaging system, made up of the world’s most advanced adaptive optics system, instruments and software. The project operates at the 200-inch Hale Telescope at California’s Palomar Observatory. Engineers at the American Museum of Natural History, California Institute of Technology, and NASA’s Jet Propulsion Laboratory worked more than six years developing the new system.

Earth’s atmosphere wreaks havoc with starlight. The heating and cooling of the atmosphere produces turbulence that creates a twinkling effect on the point-like light from a star. Optics within a telescope also warp light. The instruments that make up Project 1640 manipulate starlight by deforming a mirror more than 7 million times a second to counteract the twinkling. This produces a crystal clear infrared image of the star with a precision smaller than one nanometer; about 100 times smaller than a typical bacteria.

“Imaging planets directly is supremely challenging,” said Charles Beichman, executive director of the NASA ExoPlanet Science Institute at the California Institute of Technology. “Imagine trying to see a firefly whirling around a searchlight more than a thousand miles away.”

A coronagraph, built by the American Museum of Natural History, optically dims the star leaving other celestial objects in the field of view. Other instruments help create an “artificial eclipse” inside Project 1640. Only about half a percent of the original light remains in the form of a speckled background. These speckles can still be hundreds of times brighter than the dim planets. The instruments control the light from the speckles to further dim their brightness. What the instrument creates is a dark hole where the star had been while leaving the light reflected from any planets. Coordination of the system is extremely important, say the researchers. Even the smallest light leak would drown out the incredibly faint light from planets orbiting a star.

For now Project 1640, the world’s most advanced and highest contrast imaging system, is focusing on bright stars relatively close to Earth; about 200 light-years away. Their three-year survey includes plans to image hundreds of young stars. The planets they may find are likely to be very large, Jupiter-sized bodies.

“The more we learn about them, the more we realize how vastly different planetary systems can be from our own,” said Jet Propulsion Laboratory astronomer Gautam Vasisht. “All indications point to a tremendous diversity of planetary systems, far beyond what was imagined just 10 years ago. We are on the verge of an incredibly rich new field.”

Read more about Project 1640: http://research.amnh.org/astrophysics/research/project1640

Image Caption: Two images of HD 157728, a nearby star 1.5 times larger than the Sun. The star is centered in both images, and its light has been mostly removed by the adaptive optics system and coronagraph. The remaining starlight leaves a speckled background against which fainter objects cannot be seen. On the left, the image was made without the ultra-precise starlight control that Project 1640 is capable of. On the right, the wavefront sensor was active, and a darker square hole formed in the residual starlight, allowing objects up to 10 million times fainter than the star to be seen. Images were taken on June 14, 2012 with Project 1640 on the Palomar Observatory’s 200-inch Hale telescope. (Courtesy of Project 1640)

Posted on by Nancy Atkinson

Carnival of Space #257

Carnival of Space. Image by Jason Major.

[/caption]

This week’s Carnival of Space is hosted by our pal and contributor, Ray Sanders at his Dear Astronomer blog.

Click here to read the Carnival of Space #257.

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.

Posted on by Nancy Atkinson

Podcast: Energy

Our entire civilization depends on energy: getting it, converting it, burning it, and conserving it. But how do physicists think about energy? How do they measure and quantify it. And what is energy’s special relationship with mass?

Click here to download the episode.

Or subscribe to: astronomycast.com/podcast.xml with your podcatching software.

“Energy” on the Astronomy Cast website.

And the podcast is also available as a video, as Fraser and Pamela now record Astronomy Cast as part of a Google+ Hangout:
Continue reading “Podcast: Energy”

Posted on by Jason Major

The Return of the Rings!

Now that Cassini has gone off on a new trajectory taking it above and below the equatorial plane of Saturn, we’re back to getting some fantastic views of the rings — the likes of which haven’t been seen in over two and a half years!

The image above shows portions of the thin, ropy F ring and the outer A ring, which is split by the 202-mile (325-km) -wide Encke gap. The shepherd moon Pan can be seen cruising along in the gap along with several thin ringlets. Near the A ring’s outer edge is a narrower space called the Keeler gap — this is the home of the smaller shepherd moon Daphnis, which isn’t visible here (but is one of my personal favorites!)

The scalloped pattern on the inner edge of the Encke gap downstream from Pan and a spiral pattern moving inwards from that edge are created by the 12.5-mile-wide (20-km-wide) moon’s gravitational influence.

Other features that have returned for an encore performance are the so-called propellers, spiral sprays of icy ring material created by tiny micro-moons within the rings. Individually too small to discern (less than half a mile in diameter) these propeller moons kick up large clumps of reflective ring particles with their gravity as they travel through the rings, revealing their positions.

The three images above show a propeller within the A ring. Nicknamed “Sikorsky” after Russian-American aviator Igor Sikorsky, the entire structure is about 30 miles (50 km) across and is one of the more well-studied propellers.

Scientists are eager to understand the interactions of propellers in Saturn’s rings as they may hold a key to the evolution of similar systems, such as solar systems forming from disks of matter.

See a video of a propeller orbiting within the rings here, and here’s an image of one that’s large enough to cast a shadow!

“One of the main contributing factors to the enormous success we on the Cassini mission have enjoyed in the exploration of Saturn is the capability to view the planet and the bodies around it from a variety of directions,” Cassini Imaging Team Leader Carolyn Porco wrote earlier today. “Setting the spacecraft high into orbit above Saturn’s equator provides us direct views of the equatorial and middle latitudes on the planet and its moons, while guiding it to high inclination above the equator plane affords the opportunity to view the polar regions of these bodies and be treated to vertigo-inducing shots of the planet’s glorious rings.”

As always, keep up with the latest Cassini news on the mission site here, and read more about these images on the CICLOPS imaging team page here.

Image credits: NASA / JPL / Space Science Institute.

 

Posted on by Nancy Atkinson

Mysterious Sounds Made by the Aurora Borealis

Astrophoto: Swirling Aurora by Jason Ahrns

Caption: Swirling Aurora. Image Credit: Jason Ahrns

There have been legends and folktales about sounds associated with auroae, but most accounts were summarily dismissed as imagination or illusion. But researchers in Finland set up microphones in conjunction with an aurora observation site and over the past 12 years captured a “clapping” sound that occurs at certain times when the Northern Lights are ablaze in the sky.

“In the past, researchers thought that the aurora borealis was too far away for people to hear the sounds it made,” said Unto K. Laine from Aalto University in Finland. “However, our research proves that the source of the sounds that are associated with the aurora borealis we see is likely caused by the same energetic particles from the Sun that create the northern lights far away in the sky. These particles or the geomagnetic disturbance produced by them seem to create sound much closer to the ground.”

The researchers installed three separate microphones and were able to record the sounds, which sound similar to crackles or muffled bangs which last for only a short period of time.

They then compared the recordings and determined the location of the sound source was about 70 meters (230 feet) above ground.

They made the recordings along with simultaneous measurements of the geomagnetic disturbances by the Finnish Meteorological Institute. The sounds did not always occur, but when they did, the measurements showed the aurorae were showed of a typical pattern, according the geomagnetic measurements.

The team said that it is not yet scientifically proven that the “clap” sound is related to the aurora borealis, but similar events have been detected only during times of high geomagnetic activity.

“Our research proved that, during the occurrence of the northern lights, people can hear natural auroral sounds related to what they see,” said Laine.
The sounds are quite soft, so one has to listen very carefully to hear them and to distinguish them from the ambient noise, the team said.

Details about how the auroral sounds are created are still a mystery, Laine said. The descriptions of the sounds vary from claps, to distant noise or sputter, and the So, because of these different descriptions, researchers suspect that there are may be several mechanisms behind the formation of these auroral sounds.

Find more information on these mysterious sounds on the team’s website, Auroral Acoustics

Source: Eurekalert

Posted on by John Williams

Life and Death in a Tangled Web of Space

The Vela-C molecular cloud region as observed in far-infrared wavelengths. Credit: CNRS/INSU - Univ. Paris Diderot, France

In a star-making nebula awash in a tangled nest of gas and glowing filaments, scientists have uncovered an interesting, previously unseen interplay between gravity and turbulence that affects the formation of stars.

This image, taken by the European Space Agency’s Herschel Space Observatory, shows the highly detailed structure of cool wispy filaments of the Vela C molecular cloud. Located just 2,300 light-years from Earth, Vela-C is a vast star-making complex of gas and dust. And within this glowing cloud, both high-mass stars and smaller Sun-like stars form through very different processes.

Gravitational attraction pulls gas and dust together to form massive clumps of matter in glowing ridges. According to scientists studying the image, the most massive and brightest stars will form within these clumps. Random motion and turbulence throughout the cloud appear to create the fine nest-like filaments. It’s within these areas that smaller stars will form. Tiny, white specks fleck the image. These white dots, more abundant in the ridge-like filaments, are pre-stellar cores; compact clumps of gas and dust that might ignite into new stars.

Vela-C’s proximity to Earth makes it an ideal laboratory to study the birth of different kinds of stars. The nebula may also make it a perfect study of supernovae. The blue areas in the image contain expanding pockets of hot gas energized by the strong solar wind and ultraviolet radiation of young and massive stars. Compared to our Sun’s expected 10 billion year life-span, these massive stars burn through their supply of nuclear fuel within just a few million years. At the end of their lives, these stars will explode in dazzling supernovae.

The Herschel Telescope, launched in 2009, explores the Universe in the far infrared. While interstellar dust is cold, it shines brightly against the even colder surrounding space. The longest wavelengths of light show up as the red filaments in this image. Shorter, signifying hotter, wavelengths of light show up as yellow, green and blue.

Image Caption: The Vela-C molecular cloud region observed in far-infrared wavelengths. Credit: ESA/PACS/SPIRE/Tracey Hill & Frédérique Motte, Laboratoire AIM Paris-Saclay, CEA/Irfu – CNRS/INSU – Univ. Paris Diderot, France