For decades, dark matter and its nature and location have remained elusive to cosmologists. Recently, a team of astronomers conducted a study to locate the mysterious substance, but the results show that there is not as much dark matter as previously theorized.

“Our calculations show that it should have shown up very clearly in our measurements. But it was just not there!” Christian Moni Bidin of the Astronomy Department at la Universidad de Concepción in Chile says in the European Southern Observatory (ESO) press release. Moni Bidin also headed the study and was the lead author of the team research paper, published in The Astrophysical Journal.

Dark matter is impossible to be seen or detected. It constitutes 74% of the mass in the Universe. How it is distributed around the Universe is unknown. Astronomers believe that dark matter is what causes and exerts the gravitational force around objects made of normal matter (i.e. everything that is not dark matter or dark energy), such as planets, stars, and galaxies.

In the past, astronomers considered that one certain location of dark matter would be around galaxies: a model known as the Standard Halo Model demonstrates how galaxies form and evolve. This model also states that they rotate as quickly as they do due to dark matter, which is thought to collect around the galaxies as a halo.

Working with the 2.2-meter MPG/ESO telescope at ESO’s La Silla Observatory in Chile, the team produced a model in hopes of finding the amount, mass, density, and distribution of dark matter around the Sun (the nearest best bet for finding the substance) and our very own galaxy (the Milky Way). Utilizing a hypothesized amount of dark matter based on a past model, they measured the motions of hundreds of stars (sometimes created from the influence of dark matter) as far as 13,000 light-years away from the Sun.

But what the team observed was a lack of dark matter instead; the conjectured density was significantly lower. “The mystery of dark matter has just become even more mysterious,” Moni Bidin states.

He and his colleagues will further investigate and analyze their results. According to their paper, if matters are consistent, the distribution of dark matter would have to

“reconcile the results with the DM paradigm. The interpretation of these results is thus not straightforward. We believe that they require further investigation and analysis, both on the observational and the theoretical side, to solve the problems they present.”

“Despite the new results,” Moni Bidin continues, “the Milky Way certainly rotates much faster than the visible matter alone can account for. So, if dark matter is not present where we expected it, a new solution for the missing mass problem must be found.”

The article Dark Matter Theories Put into Question appeared first on The Toonari Post - News, Powered by the People!.

For years, astronomers have known that Sun-like stars lose most of their mass as they transition to the red giant stage, but this occurrence remained unexplainable. That is, until an international team of astronomers believes that they have solved the mystery. This discovery can shed light on stellar evolution and, more specifically, how stars age.

When stars like our Sun turn into red giants, they shed off their outer shells of gas and expand and become hundreds of times larger. Stars have “atmospheres,” which consist of powerful winds of gas and dust (which makes up much of a stars’ mass) that the stars emanate, and during their transition, the winds become 100 million times more violent. These “superwinds” occur for 10,000 years – the length of time during which usually red giants live – and cause stars to lose more than half their mass or as much so that only their cores remain.

What causes the “superwinds” has remained elusive for astronomers. Before, it had been thought that the amount of light from the red giants (which are considerably bright for main sequence stars) was absorbed by the dust grains, which were then pushed out by the light. However, all the models that were produced did not coincide with this theory.

The team consists of astronomers from the University of Manchester, Oxford and Macquarie University, University of Sydney, Australia, Paris-Diderot University, and New South Wales. Using the European Southern Observatory’s (ESO) Very Large Telescope (VLT) in northern Chile, the team looked at dying stars with a powerful resolution that allowed them to see the stars’ winds. They were surprised to see how many dust grains whirled around and how large they were. However, they were no bigger than grains of sand, but they were large for their size.

Using this information, the team was able to discover that these dust grains acted as mirrors, reflecting light from other stars. Since the grains remain cold, the star is able to push them out at 10 kilometers per second (20 million miles per hour).

“The dust and sand in the superwind will survive the star and later become part of the clouds in space from which new stars form,” Professor Albert Zijlstra, from the University of Manchester’s Jodrell Bank Observatory, said in the University of Manchester’s news release.

“The sand grains at that time become the building blocks of planets,” he continued. “Our own Earth has formed from star dust. We are now a big step further in understanding this cycle of life and death.”

Now that the mystery of superwinds has been solved, there is another for astronomers to figure out: how these dust grains form and are able to exist at their large size so close to the stars.

The article “Superwinds” of Older Stars Explained appeared first on The Toonari Post - News, Powered by the People!.

In 2007, two super-Earths known as Gliese 667 C and Gliese 581d were discovered orbiting red dwarfs in the habitable zone, an area in which a planet is able to have surface temperature in order to liquid water. Recently, results from a study suggest these planets plus smaller, rocky ones are quite common in our galaxy and orbit red dwarfs by the tens of billions.

The study was conducted by an international team of scientists a part of the HARPS (High Accuracy Radial velocity Planet Search), ESO’s (European Southern Observatory) planet finder. HARPS’s mission is to detect planets beyond the solar system. HARPS especially aims to discover planets that are in the habitable zone.

In order to calculate the largest amount of Earth-like planets that could exist in the Milky Way, HARPS studied the most common type of star in the galaxy: red dwarfs. Red dwarfs are small, cool, and faint in luminosity in comparison to the Sun. Because they spend less energy than other types of stars, they are long-lived and, therefore, are the most common. Approximately 160 billion exist in the galaxy alone, making up a whopping 80% of the total number of stars.

Using a spectrograph from a 3.6-meter telescope from La Silla Observatory in Chile, HARPS chose a sample of 102 red dwarfs from the southern portion of the sky and studied them for six days. HARPS detected nine super-Earths (planets up to ten times the size of the Earth), two of which were inside the habitable zone. Furthermore, 40% of red dwarfs contain super-Earths that are able to sustain water on their surfaces.

Combining their data and the number of stars without planets, and an estimate of how many planets could be discovered, HARPS was then able to calculate the total number of planets orbiting red dwarfs and the different types of these planets. In the end, their results illustrated that tens of billions of smaller rocky planets exist in the Milky Way.

100 of these hypothesized planets should exist in the immediate vicinity – around 30 light-years – of the Sun (smaller planets are difficult to detect). Massive gassy planets (around the size of Jupiter and Saturn), on the other hand, were calculated to be rare when it came to orbiting red dwarfs.

Although it is exciting knowing that so many Earth-sized orbit stars in the habitable zone, astronomers are not getting their hopes up of finding life. It would be difficult for life to thrive on planets that orbit red dwarfs: because red dwarfs are cool, the habitable zone is rather close, leaving any planets close to the red dwarf to be bombarded with flares of ultraviolet rays and X-rays, making the planets not habitable after all. But that does not daunt astronomers of thinking that any of these small worlds could harbor life.

“Now that we know that there are many super-Earths around nearby red dwarfs,” Xaiver Delfosse, a member of the team tells ESO, “we need to identify more of them using both HARPS and future instruments. Some of these planets are expected to pass in front of their parent star as they orbit — this will open up the exciting possibility of studying the planet’s atmosphere and searching for signs of life.”

A detailed report of HARPS experiment and results can be found here.

The article Habitable Planets by the Billions in the Milky Way appeared first on The Toonari Post - News, Powered by the People!.

On February 2, a team of astronomers detected an exoplanet (short for extrasolar planet) located in the habitable zone, a slim area in which a planet must be located, so that it is not too close nor too far away from the star it orbits, thus having a surface temperature that can sustain liquid. This newly discovered exoplanet may be able to sustain water and even life.

Using data from the European Southern Observatory, the W.M. Keck Observatory in Hawaii, and the Carnegie Planet Finder Spectograph at the Magellan II Telescope in Chile, the astronomers – from the University of California in Santa Cruz and the private research organization Carnegie Institution for Science in Washington, DC – found the exoplanet through discerning the gravitational tug it and its parent star impose on each other. The system lies 22 light-years away in the constellation Scorpius.

“This is basically our next-door neighbor,” Steven Vogt tells Space.com. Vogt, one of the members of the team, is an astronomer at the University of California. “It’s very nearby. There are only about 100 stars closer to us than this one.”

“We’ve been explicitly focusing on very nearby stars,” he adds, “because with today’s technology, we could send a robotic probe out there, and within a few hundred years, it could be sending back picture postcards.”

The star, dubbed GJ 667C, is a part of a triple star system. Unlike its companion stars, which are orange K dwarfs, GJ 667C is an M-class dwarf: it is much smaller and less luminous than the Sun and emits infrared light, which is less intense in light and temperature. GJ 667C’s composition is very different from that of the Sun’s, lacking elements heavier than hydrogen and helium such as carbon, iron, and silicon that are needed to form planets.

“We shouldn’t have really expected this star to be a likely case for harboring planets,” says Vogt.

The exoplanet, named GJ 667Cc, is a super-Earth, roughly 4.5 times the size of the Earth. Because of the absence of heavy elements, much of GJ 667Cc’s mass comes from ice and gas. The orbital period of GJ 667Cc measures 28 days, which would seem dauntingly close to us compared to the Earth’s orbital period.

A planet that takes the same amount of time to orbit the Sun (for instance) would roast; however, GJ 667C’s weak temperature and light, and the fact that GJ 667Cc receives 10 percent of the light the Earth receives from the Sun, counterbalance the closeness of the exoplanet, creating a comfortable region in which to dwell.

Furthermore, GJ 667Cc is in the right spot to absorb the same amount of energy that the Earth absorbs from the Sun to have an atmosphere. In the Carnegie Institution for Science press release, Guillem Anglada-Escudé – co-leader of the study and lead writer of the team’s paper that will soon be published in The Astrophysical Journal Letters – states, “This planet is the new best candidate to support liquid water and, perhaps, life as we know it.”

GJ 667Cc has a sibling, GJ 667Cb, which is around the size of the Earth. Unlike GJ 667Cc, GJ 667Cb has a much smaller orbital period. Hence, it is too close and has too high a temperature to sustain liquid.

Only one other exoplanet located in the habitable zone has been discovered before, Kepler-22b, which was detected by the NASA spacecraft Kepler on December 5, 2011. Astronomers believe that Kepler-22b, which is 2.4 times the Earth’s size, may also maintain water and life.

Image Courtesy of  http://www.esa.int

The article Exoplanet Possibly Harbors Water and Life appeared first on The Toonari Post - News, Powered by the People!.

Astronomers part of the international collaboration Probing Lensing Anomalies NETwork (PLANET) calculated the approximate number of planets based on statistical analyses from multiple surveys gathered from observatories, institutions, and ground-based telescopes, including NASA’s spacecraft Kepler, the European Southern Observatory (ESO), the Niels Bohr Institute, the Optical Gravitational Lensing Experiment (OGLE), and the Microlensing Observations in Astrophysics (MOA).

PLANET has taken 16 years to find planets, and six to make a statistical hypothesis (from 2002 to 2007). It is estimated that there are at least 100 billion stars in the Milky Way and that each one has 1.6 planets in orbit on average, coming to a total of 160 billion hypothetical planets. This number is much, much higher than the number originally predicted.

Astronomers use three methods to search for planets. The first one is called transiting, in which one observes a stars’ level of brightness. If the level slightly drops, the dip acts as a signal that a planet is crossing the star during its orbit. The second method is the radial-velocity method. When planets orbit a star, the star does not remain stationary.

Rather, it moves in a small circular motion, causing the planet’s gravitational pull. Lastly, the third method is gravitational microlensing. In relation to an observer on Earth, two stars, one in front of the other, seem to form a straight line. The foreground star causes light from the background star to curve, thus magnifying the latter. If there is a slight temporary difference in the light curve from the foreground star, a planet is orbiting the star.

With the former two methods, astronomers can only find low-mass planets closely orbiting stars. They are what the Kepler spacecraft uses to hunt for planets. The third one, on the other hand, is more sensitive: astronomers can find planets of all sizes (from Mercury-sized to Jupiter-sized) and those that are near and far from their parent stars. In addition, planets’ masses can be determined.

“Together,” Uffe Gråe Jørgensen states in the Niels Bohr Institute press release, “the three methods are, for the first time, able to say something about how common our own solar system is.” Jørgensen is the head of the Astrophysics and Planetary Science research group at the Niels Bohr Institute at the University of Copenhagen.

Based on the collected data, astronomers predict that Earth-like planets (small and rocky) are much more common in the galaxy than gas giants like Jupiter. According to Stephen Kane – who is a part of NASA’s Exoplanet Science Institute at the California Institute of Technology in Pasadena, California – in the HubbleSite press release, “This is encouraging news for investigations into habitable planets.”

Ultimately, this new hypothesis significantly increases the probability of the existence of extraterrestrial life, even sentient life.

The article Planets Much More Common than Stars, Astronomers Say appeared first on The Toonari Post - News, Powered by the People!.

In early December, an international team of astronomers discovered an incredibly fast rotating star, rotating at a radial velocity of 1.6 million km/h (1 million mph), which is approximately 100 times faster than the sun rotates (roughly four times a day). If the star, dubbed VFTS (short for VLT-FLAMES Tarantula Survey) 102, spun any faster, the centrifugal forces would rip it apart.

Working at the European Southern Observatory’s Very Large Telescope at the Paranel Observatory in Chile, the team located VFTS 102 160,000 light-years away from the Earth in the Tarantula Nebula, which is part of the Large Magellanic Cloud, a satellite galaxy of our Milky Way galaxy. They detected the star because its traveling velocity was 30 km/s (70,000 mph) – much faster than those of other stars in the vicinity.

Philip Dufton, lead author of the paper that presents the team’s findings, stated, “The remarkable rotation speed and the unusual motion compared to the surrounding stars led us to wonder if this star had an unusual early life.” Dufton works at the Department of Physics and Astronomy at Queen’s University Belfast, Northern Ireland. “It was suspicious.”

The centrifugal forces of VFTS 102 (which is a blue giant and has twenty-five times the mass and 100,000 times the luminosity of the sun) are so great that the star has an oblate spheroid shape. Furthermore, they cause VFTS 102 to spin out a disk of plasma at its equator.

The team of astronomers speculate that VFTS 102 had a violent past. It may have been part of a binary star system in which it and its companion star closely rotated around each other. VFTS 102′s fast rotation may have come from the two stars being so close together, which could have caused the companion star to stream gas over to VFTS 102.

Another member of the team, Matteo Cantiello, an astrophysicist at the University of California, Santa Barbara, further explains in the university’s press release, “This gas falls onto the companion star, increasing the mass and spinning it up. Similar to a tennis ball spinning fast after being hit by a glancing blow, a star rotates quickly after being hit off-center by the in-falling gas.”

At some point, the companion star went supernova, expelling much of its gas. The intense explosion ejected VFTS 102, which was sent hurdling through space at the current velocity in which it was discovered. Presently, a supernova remnant and pulsar lie near the blue giant. That these two objects are located nearby VFTS 102 serves as evidence that supports the team’s hypothesis, as the supernova remnant and pulsar may belong to the late companion star, which may have collapsed into a neutron star following its exploding.

“This is a compelling story because it explains each of the unusual features that we’ve seen,” Dufton writes. “This star is certainly showing us unexpected sides of the short, but dramatic lives of the heaviest stars.”

The article Fastest Rotating Star Discovered appeared first on The Toonari Post - News, Powered by the People!.