Astronomy Archives

December 27, 2007December 26, 2015 by Elizabeth Howell

Happy Birthday Johannes Kepler!

December 27 is a day to celebrate the life of astronomer Johannes Kepler, who was born on this date in 1571, and is best known for his three laws of planetary motion. But also, coming up in 2009, The International Year of Astronomy (IYA) will celebrate the work of Kepler as well. Not only did Galileo begin his observations with a telescope almost 400 years ago in 1609, but also in that year Kepler published his book New Astronomy or Astronomia Nova. This was the first published work that documented the scientific method.

Kepler’s primary reason for writing Astronomia Nova was to attempt to calculate the orbit of Mars. Previous astronomers used geometric models to explain the positions of the planets, but Kepler sought for and discovered physical causes for planetary motion. Kepler was the first astronomer to prove that the planets orbited the sun in elliptical paths and he did so with rigorous scientific arguments.

An offshoot of Astronomia Nova was the formulation of concepts that eventually became the first two of Kepler’s Laws:

First Law: The orbit of a planet about the Sun is an ellipse with the Sun’s center of mass at one focus.

Second Law: A line joining a planet and the Sun sweeps out equal areas in equal intervals of time.

And Kepler’s third Law: The squares of the periods of the planets are proportional to the cubes of their semi-major axes.

Kepler was also instrumental in the development of early telescopes. He invented the convex eyepiece, which allowed an expanded field of vision, and discovered a means of determining the magnifying power of lenses. He was the first to explain that the tides are caused by the Moon and the first to suggest that the Sun rotates about its axis. He also was the first to use stellar parallax caused by the Earth’s orbit to try to measure the distance to the stars.

While Kepler remains one of the greatest figures in astronomy, his endeavors were not just limited to this field. He was the first person to develop eyeglasses designed for nearsightedness and farsightedness, the first to investigate the formation of pictures with a pin hole camera, and the first to use planetary cycles to calculate the birth year of Christ. He also formed the basis of integral calculus.

Kepler’s many books provided strong support for Galileo’s discoveries, and Galileo wrote to him, “I thank you because you were the first one, and practically the only one, to have complete faith in my assertions.”

Original News Source: The Writer’s Almanac

December 26, 2007December 26, 2015 by Nancy Atkinson

It’s a Bird! It’s Tinker Bell! It’sThree Galaxies!

There once was a galaxy known as ESO 593-IG 008. It was thought to be a relatively mild-mannered galaxy, even though scientists believed it was a collision of two different galaxies; one a barred spiral and the other an irregular galaxy. But now, an international team of astronomers has discovered that it actually is a stunning rare case of three interacting galaxies, with the third galaxy forming stars at a frantic rate.

Using adaptive optics on the European Southern Observatory’s (ESO) Very Large Telescope (VLT), astronomers were able to see through the all-pervasive dust clouds of the object that has been dubbed as “The Bird” because of its resemblance to a winged creature. With the adaptive optics of what’s called the NACO instrument, very fine details were able to be resolved.

“Examples of mergers of three galaxies of roughly similar sizes are rare,” says Petri Vaisanen, lead author of the paper which will appear in the journal of the Royal Astronomical Society. “Only the near-infrared VLT observations made it possible to identify the triple merger nature of the system in this case.”

NACO is the combination of NAOS – Nasmyth Adaptive Optics System that is equipped with both visible and infrared sensors, and CONICA, a Near-Infrared Imager and Spectrograph.

Looking like a bird or a cosmic Tinker Bell, the NACO images show two unmistakable galaxies that form the body and wings of “The Bird.” Astronomers were surprised with the new images that identify a third, clearly separate component that forms the head. This irregular, yet fairly massive galaxy is forming stars violently, at a rate of nearly 200 solar masses per year. It appears to be the major source of infrared luminosity in the system, even though it is the smallest of the three galaxies. The other two galaxies appear to be at a quieter stage of their interaction-induced star formation history. The object is 650 million light years distant but it is quite large with the “wings” alone extending more than 100,000 light-years, or the size of our own Milky Way.

Subsequent optical spectroscopy with the new Southern African Large Telescope, and archive mid-infrared data from the NASA Spitzer space observatory, confirmed the separate nature of the ‘head’, but also added further surprises. The ‘head’ and major parts of the ‘Bird’ are moving apart at more than 400 km/s (1.4 million km/h). Observing such high velocities is very rare in merging galaxies.

“The Bird” belongs to the prestigious family of luminous infrared galaxies, with an infrared luminosity nearly one thousand billion times that of the Sun. This family of galaxies has long been thought to signpost important events in galaxy evolution, such as mergers of galaxies, which in turn trigger bursts of star formation, and may eventually lead to the formation of a single elliptical galaxy.

The galaxy is also designated as IRAS 19115-2124. The ESO is more formally known as the European Organization for Astronomical Research in the Southern Hemisphere.

Original News Source: ESO Press Release:

December 21, 2007December 26, 2015 by Nicholos Wethington

How Long is a Day on Saturn?

If you were on the surface of Saturn, how long would a day last? This has remained a mystery for scientists, because the thick clouds of gas obscure the surface of the planet from direct observation by telescopes or orbiters. Below all those clouds there is a surface that rotates at a constant speed. Since scientists can’t directly see the surface, they’ve taken another approach: listening.

You can also check out these cool telescopes that will help you see the beauty of planet Saturn.

With the help of radio emissions that come from the interior of Saturn, scientists have been able to close in on its rotation period. Charged particles trapped in the interior emit radio waves when they interact with Saturn’s magnetic field, at about 100 Kilohertz. It’s as if Saturn had its own radio station broadcasting at a certain frequency, and as the magnetic field deep inside the planet rotates it changes the frequency of the station.

Voyager measured these emissions for nine months when it passed by in the 1980s, and the rotation was calculated to be 10 hours 39 minutes 24 seconds, with an uncertainty of 7 seconds. The Ulysses spacecraft also monitored the emissions 15 years later, and came up with a result of 10 hours 45 minutes 45 seconds, with a 36 second margin of error.

Wait, that’s 6 minutes of difference! Either Saturn slowed down a lot over the years, or something else is going on. Cassini has been measuring these same radio emissions with its Radio and Plasma Wave Science instrument, and has observed that in addition to this long-period variation, the rotation differs by as much as one percent in a week.

Scientists think that this could be due to two different things: the solar wind coming from the Sun is interfering with the measurements, or particles from Enceladus’ geysers are affecting the magnetic field. Both of these would cause the radio emissions to vary, and they could be causing the different results simultaneously.

Cassini’s new data strongly suggests that the solar wind is a likely culprit: there is a variation in the measurements of the short-period rotation every 25 days, which corresponds with the rotation of the Sun as seen from Saturn. The speed of the solar wind, too, varies the measurements, so must be accounted for. Enceladus could be the cause of the long-term difference, but more measurements are needed to see if this is definitely the case, or if there is yet another factor.

Nailing down the rotation of Saturn will be helpful in calculating the true wind speeds of the clouds, and give important clues about the composition and distribution of the interior. Once the interference from the solar wind and Enceladus are taken into account, the true rotation of Saturn can be determined precisely.

Then only one question remains: do they have commercials on Saturn FM?

Source: ESA News Release

December 20, 2007December 26, 2015 by Fraser Cain

2009 Will Be the International Year of Astronomy

Finally, astronomy is going to get the respect it deserves. The United Nations announced today that 2009 will be the International Year of Astronomy. There’ll be a concerted effort around the world to increase awareness about astronomy, and give people access to tools, techniques and knowledge.

The year coincides with 400 years since Galileo Galilei first pointed his telescope towards the heavens. He then went on to discover mountains and craters on the Moon, and the four major moons of Jupiter.

There are going to be many many events during the International Year of Astronomy. In fact, my Astronomy Cast co-host, Dr. Pamela Gay, is going to be the New Media Chair, and help administrate the IYA 2009 website. Apparently I’ve also been volunteered for several projects – I’ll keep you posted as the details are revealed to me.

You can access the International Year of Astronomy 2009 website here.

Original Source; IAU Press Release

December 20, 2007December 26, 2015 by Fraser Cain

Supernova Generates Enough Dust for 10,000 Earths

My kids find it fascinating that the gold in the ring on my finger was formed in an instant when a massive star detonated in a supernova explosion. But it’s not just the heavier elements that get produced in a supernova, there’s also dust. Lots and lots of dust that can eventually collect together into new planets. And according to NASA’s Spitzer Space Telescope, a typical supernova remnant called Cassiopeia A contains enough dust for 10,000 Earths.

This discovery helps solve one of the outstanding mysteries in astronomy: where did all the dust from the early Universe come from? After the Big Bang, the Universe was only made of hydrogen and helium, and a few trace heavier elements. The first stars formed from this primordial material, and then exploded as supernovae, producing the first heavier elements and the dust needed to make terrestrial planets.

Astronomers always thought that supernovae were prime contributors, recycling material in generation after generation, but they weren’t sure – until now.

Another source of this dust seems to be highly energetic black holes, called quasars, which might be firing out high speed jets and dust to seed solar systems.

The Spitzer observations of Cassiopeia A, located about 11,000 light-years away, showed that the warm and cold dust ejected during the supernovae explosion adds up to about 3% the mass of the Sun.

Their observations show that the dust contains proto-silicates, silicon dioxide, iron oxide, pyroxene, carbon, aluminium oxide and other compounds. You could fashion 10,000 planets with the mass of the Earth with that much material.

Although Cassiopeia A is nearby, and not one of those first stars, it wasn’t working with the same raw primordial materials. But the research shows that exploding massive stars do a fine job of turning raw hydrogen and helium into the dust needed to form planets like Earth.

Original Source: Spitzer News Release

December 19, 2007December 26, 2015 by Fraser Cain

Galaxy Has 1,000 Times Our Rate of Star Formation

Here in the Milky Way, new stars are formed at a rate of roughly 4 per year; that’s considered pretty normal for spiral galaxy like ours. But researchers have found a galaxy that’s absolutely bursting with new star formation. Instead of our leisurely 4 stars per year, this distant galaxy is generating more than 4,000 new stars a year.

The galaxy, known at GOODS 850-5, is located about 12 billion light-years from Earth. This means that astronomers are seeing the light coming from it at a point when the Universe was only 1.5 billion years old.

All of the star formation in this galaxy was obscured by thick layers of dust, emitted by all the stellar nurseries. This means they’re hidden by visible-light telescopes.

By using the Smithsonian Astrophysical Observatory’s Submillimeter Array (SMA) on Mauna Kea in Hawaii, the researchers were able to peer right through the obscuring dust to calculate the rate of star formation.

The irony is that the dust from all that star formation was obscuring the, uh, star formation. Here’s Wei-Hao Wang, one of the astronomers who worked on the research:

“This evidence for prolific star formation is hidden by the dust from visible-light telescopes,” Wang explained. The dust, in turn, was formed from heavy elements that had to be built up in the cores of earlier stars. This indicates, Wang said, that significant numbers of stars already had formed, then spewed those heavy elements into interstellar space through supernova explosions and stellar winds.

This discovery has come as a bit of a surprise, since astronomers used to think that the most actively star forming galaxies would be smaller and less obscured. Now they’re starting to realize that it’s actually the big dusty galaxies that form the most stars. We just couldn’t see it.

For a galaxy to be experiencing this much star formation, it must have gone through many rounds of mergers with other galaxies. And this is also surprising, considering it’s only 1.5 billion years old in the image.

Original Source: NRAO News Release

December 19, 2007December 26, 2015 by Fraser Cain

Astronomers Track Flares on a Distant Star

Spotting flares on the surface of the Sun is easy. It’s right there, blazing in our skies. But watching flares erupt on the surface of a distant star, located 150 light-years away… now that’s a challenge. And yet, a team of European astronomers announce just such a discovery this week.

This accomplishment was made by a team of astronomers using the European Southern Observatory’s Very Large Telescope and ESA’s XMM-Newton X-ray satellite.

The astronomers were watching the star BO Microscopii, nicknamed “Speedy Mic” because of its rapid rotation. The star is slightly smaller than the Sun, and located about 10 million times as far away.

According to the press release, imaging the surface is crazy hard:

Trying to see spots on its surface is as challenging as trying to directly obtain a photograph of the footsteps of Neil Armstrong on the Moon, and be able to see details in it. This is impossible to achieve even with the best telescopes: to obtain an image with such amount of details, you would need a telescope with a 400 km wide mirror!

So how did they do it? They used a technique called “Doppler imaging”, which measures slight changes in the star’s light as it rotates. These changes can be mapped into spots and flares on the star’s surface as it turns.

Over the course of 142 separate observations, the team identified several flares. One flare lasted 4 hours long, and would have generated about a hundred times as much energy as the flares we see on the Sun.

Since BO Microscopii is much younger than the Sun, only 30 million years young, it can give us valuable clues about our star’s early history. Perhaps the early Sun was this active, and then settled down in later life.

Original Source: ESO News Release

December 19, 2007December 26, 2015 by Fraser Cain

When the Solar System Went from Dust to Mountains

Astronomers are slowly piecing together the earliest phases of our Solar System’s history. At some point, tiny particles of dust clung together forming larger and larger boulders and eventually even mountain-sized chunks of rock. Researchers from UC Davis have pegged the date that this occurred to 4.568 billion years ago, give or take a few million years.

The evolution of the Solar System is believed to have gone through several distinct stages. The first stage occurred when tiny particles of interstellar dust linked up, created boulders, and leading up to the mountain-sized rocks.

In the second stage, these mountains collected into about 20 Mars-sized objects. In the third and final stage, these mini-planets smashed into one another, eventually leading to the large planets we have today. The dates of the second and third stages are fairly well known, but the timing of the first stage has largely been a mystery.

To get an idea of when that first stage took place, researchers from UC Davis analyzed a particular kind of meteorite, called carbonaceous chondrites. These represent some of the oldest material in the Solar System.

They found that the meteorites have very stable ratios of certain elements, which can allow them to be dated. Since the rocks never got large enough to heat up from radioactive decay, they’re cosmic sediments from the early Solar System.

The UC Davis researchers estimated the timing of their formation to 4.568 billion years ago, ranging from 910,000 years earlier or 1.17 million years later.

“We’ve captured a moment in history when this material got packed together,” said Qing-zhu Yin, assistant professor of geology.

The work is published in the Dec. 20 issue of Astrophysical Journal Letters.

Original Source: UC Davis News Release

December 18, 2007December 26, 2015 by Fraser Cain

Mysterious Explosion Comes Out of Nowhere

When astronomers find a gamma ray burst, they can usually locate the culprit’s home galaxy. But in the case of an explosion that went off earlier this year, there’s no galaxy to be found – even with the most powerful telescopes on Earth.

The gamma ray burst GRB 070125 was first detected on January 26th, 2007 by NASA’s Swift telescope in the constellation Gemini. One of the brightest bursts of the year, astronomers scrambled to observe the explosion and then the slowly fading afterglow.

Gamma ray bursts occur when a massive star runs out of fuel. Without the light pressure, the star collapses inward on itself, turning into a black hole. This newly formed black hole spins at an enormous rate, generating enormous magnetic fields. These fields catch infalling material and spew it out again into powerful jets. And it’s those jets where the burst comes from.

One of the normal activities in observing GRBs is the identify the host galaxy so that astronomers can measure its distance. It’s also important to know what kind of galaxy the burst exploded within to better understand the kinds of environments can lead to these massive stars.

In the case of GRB 070125, though, no originating galaxy was obvious. Astronomers from Caltech/Penn State used the 60-inch Palomar Observatory to watch the afterglow, and then called in the even larger Gemini North and Keck 1 telescopes, located on Hawaii’s Mauna Kea.

Even with the power of Keck, they couldn’t find a galaxy.

So how could you get a gamma ray burst without a galaxy? Astronomers know that colliding galaxies can throw off enormous tidal tails that stretch away for hundreds of thousands of light-years. The original star could have been within one of these tidal tails, many light-years away from its parent galaxy.

If their theory is correct, a long duration exposure from the Hubble Space Telescope should reveal the dim tidal tail.

Original Source: NASA News Release

December 17, 2007December 26, 2015 by Fraser Cain

Galactic Black Hole Fires a Jet at a Nearby Neighbour

Ouch, that’s going to leave a mark. A new photograph captured by NASA’s Chandra X-Ray Observatory shows a powerful jet blasting out of one galaxy, and colliding with another. As the jet tears through the galaxy, it could have serious implications for planetary formation, and trigger a wave of new star formation.

The image contains two galaxies, collectively known as 3C321, in orbit around one another. X-ray images from Chandra show that they both have supermassive black holes at their centres.

The black hole in the larger galaxy is actively feeding, and has an enormous jet of radiation and material blasting out into space. Unfortunately, the smaller galaxy has gotten caught right in the crossfire of this jet.

“We’ve seen many jets produced by black holes, but this is the first time we’ve seen one punch into another galaxy like we’re seeing here,” said Dan Evans, a scientist at the Harvard-Smithsonian Center for Astrophysics and leader of the study. “This jet could be causing all sorts of problems for the smaller galaxy it is pummeling.”

So what kinds of problems? For starters, the jet has a tremendous amount of radiation, especially high-energy X-rays and gamma-rays. An ongoing blast of this radiation could strip away planetary atmospheres and blow away newly forming stellar nurseries. In other cases, the jet could cause a cloud of gas and dust to collapse in the first place, setting the stage for new star formation.

Since the two galaxies are only 20,000 light years apart – the same distance of the Solar System to the middle of the Milky Way – the effect of the jet will be extreme. One bright part of the image shows where the jet is colliding with the galaxy, and then getting disrupted and deflected away.

This event is probably very short-lived. Astronomers estimate that the jet only began impacting the galaxy about a million years ago; a blink of the eye in cosmological terms.

Original Source: Chandra News Release