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.”

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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.

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Interstellar Boundary Explorer (IBEX) has captured the best and most complete glimpse yet of what lies beyond the solar system. The new measurements give clues about how and where our solar system formed, the forces that physically shape our solar system, and the history of other stars in the Milky Way.

The Earth-orbiting spacecraft observed four separate types of atoms including hydrogen, oxygen, neon and helium. These interstellar atoms are the byproducts of older stars, which spread across the galaxy and fill the vast space between stars. IBEX determined the distribution of these elements outside the solar system, which are flowing charged and neutral particles that blow through the galaxy, or the so-called interstellar wind.

“IBEX is a small Explorer mission and was built with a modest investment,” said Barbara Giles, director of the Heliophysics Division at NASA Headquarters in Washington. “The science achievements though have been truly remarkable and are a testament to what can be accomplished when we give our nation’s scientists the freedom to innovate.”

In a series of science papers appearing in the Astrophysics Journal on Jan. 31, scientists report finding 74 oxygen atoms for every 20 neon atoms in the interstellar wind. In our own solar system, there are 111 oxygen atoms for every 20 neon atoms. This translates to more oxygen in any part of the solar system than in nearby interstellar space.

“Our solar system is different than the space right outside it, suggesting two possibilities,” says David McComas, IBEX principal investigator, at the Southwest Research Institute in San Antonio. “Either the solar system evolved in a separate, more oxygen-rich part of the galaxy than where we currently reside, or a great deal of critical, life-giving oxygen lies trapped in interstellar dust grains or ices, unable to move freely throughout space.”

The new results hold clues about the history of material in the universe. While the big bang initially created hydrogen and helium, only the supernovae explosions at the end of a star’s life can spread the heavier elements of oxygen and neon through the galaxy. Knowing the amounts of elements in space may help scientists map how our galaxy evolved and changed over time.

Scientists want to understand the composition of the boundary region that separates the nearest reaches of our galaxy, called the local interstellar medium, from our heliosphere. The heliosphere acts as a protective bubble that shields our solar system from most of the dangerous galactic cosmic radiation that otherwise would enter the solar system from interstellar space.

IBEX measured the interstellar wind traveling at a slower speed than previously measured by the Ulysses spacecraft, and from a different direction. The improved measurements from IBEX show a 20 percent difference in how much pressure the interstellar wind exerts on our heliosphere.

“Measuring the pressure on our heliosphere from the material in the galaxy and from the magnetic fields out there will help determine the size and shape of our solar system as it travels through the galaxy,” says Eric Christian, IBEX mission scientist, at NASA’s Goddard Space Flight Center in Greenbelt, Md.

The IBEX spacecraft was launched in October 2008. Its science objective is to discover the nature of the interactions between the solar wind and the interstellar medium at the edge of our solar system.

The Southwest Research Institute developed and leads the IBEX mission with a team of national and international partners. The spacecraft is one of NASA’s series of low-cost, rapidly developed missions in the Small Explorers Program. Goddard manages the program for the agency’s Science Mission Directorate at NASA Headquarters in Washington.

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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.”

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The Drake equation is a probability law which estimates the abundance of intelligent life in our Galaxy, the Milky Way. It is quite simple in appearance, and anyone can play with the variables in order to make their own personal estimate.

The variables encountered in the equation include the proportion of intelligent to non-intelligent life; the proportion of stars which would be capable of sustaining life in their environment to those who cannot; the number of planets a star is probable to have existing in this habitable zone, if the star were to harbour planets.

Although the scientific results of this equation are in great debate, it was developed by Prof. Frank Drake in order to open discussion on the topic for the famous meeting at the Green Bank radio observatory in 1961.

Current estimates ranging from the opinions of pessimists to optimists, are of the order of it being next to impossible to communicate with other lifeforms in our Galaxy, to a possible ten different alien civilisations who are currently in the same positions as us with appropiate technology who could be trying to communicate with us and others like us.

Hence the popularity of the SETI project (the Search for Extraterrestrial Intelligence). The equation brings many interesting topics to light such as how long intelligent civilisations may continue on living, with most estimates being of short duration. One hypothesise is that once nuclear power is developed by a civilisation, they will quickly destroy themselves through their new technology.

To date there have been 684 confirmed planets discovered orbiting a total number of 474 stars other than our Sun. With thousands more proposed from the Kepler mission awaiting comfirmation. More recently the Kepler mission has discovered the first planet known to be orbiting two stars.

The techniques involved in detecting these extra-solar (i.e. orbiting other stars than our Sun) objects favor the discovery of larger, more massive planets which have a more visible influence on their parent star. The techniques follow principles as simple as; does the parent star wobble?

If so, by how much and then knowing the distance to the parent star we can calculate the mass of the orbiting planet and orbital period, which in turn would give us the distance between the parent star and planet, using Kepler’s third law. This technique follows the principles of astrometry (basically astronomical geometry).

Then from analyzing the richness of the chemical environment of such systems through spectroscopy it is possible to say if at least one component of this system would be capable of sustaining life. Unfortunately, due to the large number of complexities which arise in the observational and analysis stages no one can say for sure if these planets are currently harbours of life.

However, all is not lost as we know already that our solar system contains life on a small out of the way planet amicably called Earth. So would it be possible for other lumps of rock in our Galaxy to host complex biological species? It is of popular opinion that yes, it is possible but due to the harsh environments in which they may exist they may not of had the possibility to evolve beyond microbial stages of evolution.

For example, if we ignore Mars for a minute and concentrate on the more probable hosts, the Gaililean satelites orbiting our local failed star Jupiter or Saturn’s Titan are good bets. It was initially thought that light was a neccessary ingredient for life to come into being. That was until the discovery of strange looking creatures living in the depths of our deepest darkest oceans close to hydrothermal vents.

This would lead a reasonable mind to believe that Europa, Ganymede or Titan may be hosts to such creatures thanks to their water ice crusts encasing their volcanic prone H2O oceans. How could we detect such life? Well as we know from studies of biological creatures back home we create a chemical diversity in our atmosphere which wouldn’t exist if we did not.

So we could look for gases such as methane trapped in ice crystals such as Clathrate Hydrates on the surface of these near by objects, with techniques such as infra-red reflection spectroscopy.

An exo-planet nicknamed ‘Snow White’ has been found to have a partially water ice surface with a possible light methane atmosphere. So in conclusion, no life has been currently detected aside from on planet Earth and it will prove difficult to find, but, we are off to a good start.

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