Cosmic to Quantum

Dwarf planet Eris may reveal quantum gravity

KILLING Pluto was only the beginning. The dwarf planet Eris, named for the Greek goddess of strife, could also bring down the most popular explanations for dark matter and dark energy.

Many galaxies appear to have stronger gravity - and thus more mass - than can be explained by their visible matter alone. Overly massive galaxies are most often attributed to dark matter, an invisible substance that interacts with matter through gravity. To date, though, no one has directly detected dark matter particles.

But a well-established notion in physics could hold another explanation for their size. This says that empty space is really a frothy, turbulent sea full of virtual particles - matter and antimatter that spring in and out of existence so fast that we can’t see them.

Though they are tiny, quantum objects, Dragan Hajdukovic, a physicist at CERN near Geneva, Switzerland, thinks these bubbling particles may have opposing gravitational charges, similar to electrical charges. In the presence of a gravitational field, the particles would generate a secondary field, which, in the case of galaxies, could explain the mass discrepancy.

Hajdukovic’s theory could also explain dark energy, the baffling force thought to be driving the universe apart at an accelerated pace. If virtual particles have gravitational charges, then space-time itself is imbued with a small charge that could be causing objects in the universe to speed away from each other.

To test whether quantum-scale gravity is at work, Hajdukovic plans to borrow a trick from Einstein (see diagram). Due to gravitational effects in the solar system, such as the tug of other planets, Mercury’s oval-shaped path around the sun slowly turns, or precesses. In the 1800s astronomers noticed that this happens at a different rate than predicted by Newtonian physics. Einstein showed that the sun’s mass creates a curvature in space-time that affects Mercury enough to explain the difference, lending credence to his theory of general relativity.

Hajdukovic’s quantum gravity might create a similar discrepancy with more distant orbiting bodies, he says - which is where Eris and its moon Dysnomia come in.

Best known for depriving Pluto of planethood by showing that there are many similar bodies in orbit beyond Neptune, Eris’s great distance from the sun means the effects of general relativity become negligible. Newtonian physics should dominate, putting Dysnomia’s precession rate around Eris at 13 arc seconds per century. But if quantum gravity exists, the rate should be -190 arc seconds per century, Hajdukovic calculates (Astrophysics and Space Science, doi.org/j6r).

He thinks the required measurements could be made from Earth using existing observatories. “Einstein was lucky that there is a planet so close to the sun as Mercury,” he says. “My theory might be lucky that there are trans-Neptunian objects allowing astronomical tests.”

Gary Page of Longwood University in Farmville, Virginia, is sceptical that Earth-based tests would be sensitive enough to pick up the effect. Still, he praises Hajdukovic for going beyond the party line. “It’s always good when people are willing to go a little bit out on a limb.”

By: Ker Than

the-star-stuff:

White Dwarfs

A white dwarf is the remnant of an average-sized star that has passed through the red giant stage of its life. After the star has used up its remaining fuel. At this point the star may expel some of its matter into space, creating a planetary nebula. What remains is the dead core of the star. Nuclear fusion no longer takes place. The core glows because of its residual heat. Eventually the core will radiate all of its heat into space and cool down to become what is known as a black dwarf. White dwarf stars are very dense. Their size is about the same as that of the Earth, but the contain as much mass as the Sun. They are extremely hot, reaching temperatures of over 100,000 degrees.

Illustration By Gary’s TT

Record Nine-Planet Star System Discovered?
Alien star likely has more planets than the sun, astronomers say.

A star about 127 light-years from Earth may have even more planets than thesun, which would make the planetary system the most populated yet found.

According to a new study, HD 10180—a sunlike star in the southern constellation Hydrus—may have as many as nine orbiting planets, besting the eight official planets in our solar system.

The star first made headlines in 2010 with the announcement of five confirmed planets and two more planetary candidates.

Now, reanalysis of nearly a decade’s worth of data has not only confirmed the existence of the two possible planets but also uncovered the telltale signals of two additional planets possibly circling the star, bringing the total to nine.

“There certainly is, according to my results, strong evidence that this is the most populous planetary system detected—possibly even richer than the solar system,” said study leader Mikko Tuomi, an astronomer at the University of Hertfordshire in the U.K.

“But the two new planetary signals I report exceed the detection threshold only just.”

Early indications are that both newly detected worlds are super-Earths—planets slightly larger than Earth with rocky surfaces—but more measurements will be needed to confirm their existance.

Scorching Super-Earths

The planetary system around HD 10180 is too far from Earth for us to see directly. 

Instead, astronomers detected the planets by measuring their gravitational tugs on the host star using the High Accuracy Planet Searcher (HARPS) instrument on the European Southern Observatory’s 3.6-meter telescope at La Silla, Chile.

The five established planets are between 12 and 25 times the mass of Earth and are all around the sizes of Uranus or Neptune, meaning the worlds are most likely icy gas giants.

Of the two newly confirmed planets, one is about 65 times the mass of Earth, and it orbits farther beyond the main group. The other planet is a super-Earth 1.3 times the mass of our home world that circles very close to the host star.

The two new, unconfirmed planets also have tight orbits: A planet thought to be 1.9 times the mass of Earth completes its orbit in 10 days, while the other world is likely 5.1 Earth masses with an orbit lasting 68 days.

That means, if the planets do exist, they’d be unlikely candidates to host life.

“They are likely hot planets without dense, gaseous atmospheres, because they are just so close to their star,” Tuomi said.

The astronomer now hopes to take more measurements and verify the planets are really there.

Tuomi also hopes to scan the skies for other crowded planetary systems like HD 10180. (Also see “‘Solar Systems’ Common Across the Galaxy, NASA Probe Hints.”)

“We have only just started to detect planets, and the known exoplanet systems are but a tip of the iceberg,” he said.

“So [our] solar system is only one example among a spectrum of different planetary systems we will find in the near future and [is] definitely not unique.”

The new research on the HD 10180 planetary system appears online this week on the website arXiv.org and has been accepted for publication in the journal Astronomy and Astrophysics.

Andrew Fazekas, National Geographic News

the-star-stuff:

Stunning Jupiter and Io picture

It’s a montage of two images, both of which are real but were taken separately. They were taken by NASA’s New Horizons probe, which passed Jupiter in 2007. New Horizons is on its way to Pluto, and flew past Jupiter to steal some of its energy and boost the speed of the probe.

The shot of Jupiter is actually a composite of three images taken in the infrared, well past what the human eye can see. That big blue spot is actually the Great Red Spot! But the scientists applied a false color to the infrared images for this picture. The different colors more or less show cloud height: high-altitude clouds are blue, and clouds deeper in the Jovian atmosphere are red.

Io is actually depicted as more true to what your eye would see — it’s shown in visible light, not infrared. However, that image of the moon was taken nearly a day after the Jupiter pictures were taken! The two pictures were stitched together later. The red spot is an active volcano on Io, and the blue swoosh is the plume of ejecta reaching well above the moon’s surface.

Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Goddard Space Flight Center

thenewenlightenmentage:

Why Giant Alien Planets Like Some Orbits More than Others

Some zones encircling baby stars are far more popular than others, drawing crowds of giant planets while the other potential paths for orbits remain empty.Now computer simulations may reveal why, scientists say.

When astronomers began discovering giant alien planets similar to Jupiter and Saturn outside our solar system, they noticed that the orbits of these giants weren’t spread out in regular intervals from baby stars. Instead, certain orbital distances seemed strangely attractive to these giants.

Read More

NASA Probe Spurs new View of Mercury’s Interior

Mercury is a planet of many superlatives: speediest, smallest, nearly the hottest, and almost the most dense. It might also be the oddest.

Scientists with MESSENGER (Mercury surface, space environment, geochemistry and ranging), a NASA mission that has just completed one year in orbit, today revealed their depiction of the radical and strange interior structure they think lies beneath the planet’s cracked terrain. The proposal — a thin, solid shell of iron sulphide that envelopes the outer liquid core — would help explain the the planet’s gravity field, but also presents problems in explaining the planet’s relatively recent geological upheavals.It seems that Mercury has a novel internal structure,” says Steven Hauck, a planetary scientist on the team at Case Western Reserve University in Cleveland, Ohio. (Read More)