Interstellar ‘Oumuamua now believed to be a comet

Material ejected via outgassing is causing object to travel faster than expected through the solar system.

‘Oumuamua, the interstellar object racing through the solar system, is now believed to be a comet rather than an asteroid.

First discovered in October 2017, ‘Oumuamua has been observed by both the Hubble Space Telescope (HST) and by ground-based telescopes moving faster through the solar system than scientists had predicted.

While its speed is being slowed by the Sun’s gravitational pull, this is occurring at a rate lower than that expected by calculations of celestial mechanics.

Marco Micheli of the European Space Agency (ESA), leader of a study on ‘Oumuamua’s movements published in the journal Nature, attributes its faster-than-expected movement to the object outgassing or venting material from its surface as a result of being heated by the Sun. He theorizes the small amount of ejected material is giving the object a slight push in its trajectory out of the solar system.

‘Oumuamua was traveling at a speed of 70,836 miles (114,000 km) per hour on June 1.

Outgassing is a feature of comets, not asteroids, and involves the ejection of gas and dust that form a coma or cloud around the objects as a result of solar heating.

In ‘Oumuamua’s case, scientists did not actually see development of a coma or tail but suspect the object is venting large, coarse dust grains, possibly due to its smaller dust grains having eroded during its journey through interstellar space. Hubble cannot detect clouds of large dust grains because they are not very bright.

“We think this is a tiny, weird comet. We can see in the data that its boost is getting smaller the farther away it travels from the Sun, which is typical for comets,” Micheli said.

When ‘Oumuamua was first detected last year, scientists were uncertain as to whether it should be classed as an asteroid or a comet.

The researchers’ initial reason for observing the object with Hubble was an effort to trace its path back to the star system from which it originated. Its unexpected increase in speed makes that a more difficult task, meaning scientists may never know its true origin.

 

Undetected asteroid explodes over Russia

Impact highlights gaps in ability to detect some potentially hazardous Near-Earth Objects.

Just days after NASA announced a 10-year plan to improve its capability to track potentially hazardous asteroids, an undetected asteroid exploded over Russia.

No injuries or damages were reported from the impact, which occurred on Thursday, June 21 at 1:15 Universal Time (UT) or 4:15 AM local time. Estimated to have been 13 feet (four meters) in diameter, the asteroid exploded in a fireball over the Russian city of Lipetsk southeast of Moscow.

Accompanied by a loud sonic boom, the fireball was seen by residents of the Russian cities of Kursk, Voronzeh, and Orel. It exploded around 16.7 miles (27 km) above Earth’s surface.

Traveling at an estimated 32,200 miles  per hour (52,000 km per hour), the asteroid was estimated to have the energy of 2.8 kilotons of TNT, much less than that of the one that impacted Chelyabinsk in February 2013, which was estimated to have had the power of 440 kilotons of TNT and injured close to 1,500 people.

Nine stations run by the International Meteor Organization (IMO), an international non-profit group of amateur meteor observers, detected the fireball produced by the asteroid, as did several weather satellites and NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California.

A local observer caught the explosion on video and uploaded the footage online.

Last week, NASA reported its detection systems do not always find asteroids coming towards Earth from its “day side.”

An 18-page report released by the White House Office of Science and Technology Policy this month outlines a 10-year plan to protect the planet from impacts by boosting tracking capabilities, enabling earlier detection of potential impactors.  Improved technology described in the report will help scientists more accurately predict the likelihood of particular asteroids hitting the Earth.

According to NASA planetary defense officer Lindley Johnson, scientists have detected 95 percent of all potentially hazardous asteroids and comets with diameters of two-thirds of a mile (one km) or larger.

All asteroids and comets orbiting within 30 million miles of Earth are considered Near-Earth Objects (NEOs).

The remaining five percent of asteroids that remain undetected, as well as smaller ones, could still pose significant threats to the planet.

Titled “The National Near-Earth Object Preparedness Strategy and Action Plan,” the report establishes five goals, including better detection and tracking methods, improved computer modeling, development of deflection technologies, more international cooperation on the issue, and establishing emergency procedures should a threat be discovered.

Space rock gives evidence of Planet Nine

An asteroid known as 2015 BP519 could be some of the best evidence of Planet’s Nine existence

A team of astronomers from various U.S. universities have discovered a new strange space rock that gives new evidence for the existence of the mysterious Planet Nine, according to a new study that is available on the preprint website Arxiv and has been submitted to The Astronomical Journal.

Scientists have spent years searching for the hypothetical ninth planet within our solar system. In the recent research, the scientists found that an asteroid known as 2015 BP519 likely supports the theory of the world’s existence.

The body is important because its orbit is at an angle that suggests it is being affected by a large planet floating somewhere out in the far reaches of our solar system.

“We…consider the long term orbital stability and evolutionary behavior within the context of the Planet Nine hypothesis, and find that 2015 BP519 adds to the circumstantial evidence for the existence of this proposed new member of the solar system,” the team wrote in their study, according to Space.com.

Though not all scientists believe the odd orbit is proof that Planet Nine exists, may agree it does give more credence to the idea. In fact, putting Planet Nine into simulations helps account for the rock’s strange movements.

This is not the first time astronomers have attributed Planet Nine to a strange orbit. In 2014 scientists discovered similar patterns in several small bodies beyond Neptune’s orbit, including dwarf planet Sedna, a newfound object called 2012 VP113, and several other trans-Neptunian objects (TNOs).

Many studies have been conducted on TNOs since then, but very few of them gave as much evidence to the Planet Nine hypothesis as the recent finding. Now that researchers are aware of 2015 BP519’s orbit, they next plan to take a closer look at the rock and run more model simulations to see if they could find where Planet Nine might be. 

“It’s not proof that Planet Nine exists,” said study co-author David Gerdes, a researcher from the University of Michigan, according to Science Alert. “But I would say the presence of an object like this in our solar system bolsters the case for Planet Nine.”

Complex, carbon-rich molecules found on Enceladus

New research on Enceladus shows that it has the potential to harbor simple extraterrestrial life.

A team of international astronomers have found organic, carbon-rich molecules on Saturn’s moon Enceladus, according to a new study published in the journal Nature.

This finding is important because it suggests the thin film that sits  atop the satellite’s oceans could be rich in organic compounds. If that were to be true, it would also further reinforce the popular theory that the moon has simple marine organisms living deep beneath its icy crust.

Previous molecules found in studies on the small celestial body measured around roughly 50 atomic units and only had a handful of carbon atoms. In contrast, the newly discovered ones are much more complex. In fact, Enceladus is not the only known celestial body to have all of life’s basic requirements as we currently understand them.

“We are, yet again, blown away by Enceladus,” said study co-author Christopher Glein, a geochemist and planetary scientist of the Southwest Research Institute, according to Science Alert. “We’ve found organic molecules with masses above 200 atomic mass units. That’s over ten times heavier than methane.”

This builds on past research that found molecular hydrogen exists in the plumes shooting off the moon’s surface. While there is no proof that certain organisms call the hostile environments home, small organisms do exist in such areas on Earth. As a result, such life could exist near the vents.

However, despite the fact that it is plausible — especially considering the new research — nobody is sure what those organisms would look or how they would behave. Those are extremely important questions, and the new research could be the first step towards answering them.

“This is the first-ever detection of such a large and complex organic molecules on an extraterrestrial water world,” said study co-author Nozair Khawaja, a researcher at the University of Heidelberg’s Institute of Geosciences, told Gizmodo.

Planets can form before stars are fully grown

Scientists do not know whether early planet formation is an anomaly or common to very young stars.

Scientists have discovered evidence of planet formation in the disk of dust and gas surrounding a young star that is not fully grown.

Using the Atacama Large Millimeter/submillimeter Array (ALMA), a network of 66 connected radio telescopes that covers nearly ten miles (16 km) in Chile’s Atacama Desert, a group of astronomers from the Netherlands, Denmark, and Sweden observed TMC1A, a star in the constellation Taurus that is still in the process of developing.

In one part of the protoplanetary disk surrounding the star, the researchers detected a lack of carbon monoxide radiation, which they attributed to large dust particles in the area.  To test the theory, they inputted the data into numerical computer models, which indicated rapid growth of dust particles from approximately one-thousandth of a millimeter to one millimeter in this region of the disk.

“The results indicate that planets already start forming while the star is still developing,” noted lead researcher Daniel Harsono of Leiden University in the Netherlands.

Major questions continue to puzzle scientists regarding the process of planet formation, especially how it produces such a wide variety of planet masses and numbers in different star systems. This discovery suggests planet formation begins significantly earlier than researchers expected, before parent stars are fully grown.

“Only early protoplanetary disks contain sufficient mass to form giant planets,” said Per Bjerkeli of Chalmers University in Sweden. Formation of giant planets may have already begun in this particular system.

Scientists will have to study protoplanetary disks surrounding other protostars to determine whether the start of planet formation around TMC1A is typical or an exception.

“Maybe this young disk is very special,” commented research team member Matthijs van der Wiel of the Netherlands Institute for Radio Astronomy (ASTRON).

Findings of the study have been published in the journal Nature Astronomy.

Most asteroids come from a few ancient planetesimals

Eighty-five percent of inner main belt asteroids come from five or six ancient objects.

Most asteroids in the belt between Mars and Jupiter as well as meteorites on Earth are the remnants of five or six planetesimals that broke apart in the ancient solar system, according to a new study published in the journal Nature Astronomy.

The asteroid belt is home to about 400,000 asteroids, with those posing the greatest possible threat to Earth located mostly in the inner main belt.

Understanding the origin and evolution of asteroids is important to protecting the Earth from potential impactors, noted study lead author Stanley Dermott of the University of Florida.

“These large bodies whiz by the Earth, so of course we’re very concerned about how many of these there are and what types of materials are in them. If ever one of these comes toward the Earth, and we want to deflect it, we need to know what its nature is.”

In earlier studies, scientists found that many asteroids have very similar compositions and orbits, which they labeled “asteroid families.” Each family likely originated from one larger body broken apart in a long ago impact.

Prior to this study, scientists believed just 44 percent of inner main belt asteroids to belong to five asteroid families.

Dermott and his research team studied asteroids never assigned to any families, specifically focusing on whether their orbits are circular or eccentric along with their tilt or inclination to the Sun’s equator. Their findings indicated 85 percent of inner main belt asteroids come from just five asteroid families. The remaining 15 percent either come from these same families or come from “ghost families,” most of whose asteroids have since been destroyed.

Meteorites on Earth, all of which are somewhat different from one another, also came from the same initial, ancient objects. “We’re saying these meteorites generally come from a small number of objects that were fairly large, hundreds of kilometers in diameter or more,” Dermott added.

Asteroids in the middle and outer main belt likely come from a different, but equally small number of larger parent bodies.

As a next step, Dermott plans to research the process by which asteroids leave the main belt and travel inward to become Near-Earth Objects.

A better understanding of ancient solar system bodies will also help scientists better understand the processes that shaped Earth and provide insight as to where to look for Earth-like exoplanets, he said.

 

Milky Way disk spans 200,000 light years

Metal-rich stars have been discovered far beyond what was thought to be the galactic disk’s boundary.

The Milky Way’s disk, the flat, central region of the galaxy that contains mostly young stars, gas, and dust within the structure of its spiral arms, measures 200,000 light years across, making it significantly larger than initially thought, according to a new study.

Previous studies calculated the galaxy’s diameter at 100,000 to 160,000 light years.

In the most recent study, scientists analyzed data collected by the Apache Point Observatory Galactic Evolution Experiment (APOGEE) and by the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) on the spectra of stars in the galactic disk.

A star’s spectrum breaks down its light into different colors whose patterns reveal the specific elements present within that star.

For this study, researchers analyzed the metallicities or amounts of heavy elements, within disk stars and were surprised to find stars with high metallicities beyond the region they believed to be the boundary of the galaxy’s disk.

“We have shown that there is an appreciable fraction of stars with higher metallicity, characteristic of disk stars, further out than the previously assumed limit on the radius of the galaxy disk,” said Carlos Allende of the Astrophysics Institute of the Canary Islands (IAC).

Although spiral disks are usually thin, that is not the case for the Milky Way. “The disk of our galaxy is huge, around 200,000 light years in diameter,” stated Martin Lopez-Corredoira, also of the Astrophysics Institute.

The newly-discovered metal-rich disk stars are located about three times further and possibly as far as four times further from the galactic center than our Sun.

One light year is equal to approximately six trillion miles (10 trillion km). A spacecraft traveling at the speed of light would take 200,000 years to cross from one end of the galaxy to the other.

A paper detailing the study’s findings has been published in the journal Astronomy and Astrophysics.

Astronomers continue search for elusive Planet Nine

All circumstantial evidence points towards a new planet, but detecting it remains near impossible.

Many astronomers remain convinced that they will one day locate the mysterious Planet Nine, the hypothetical body thought to be hiding far beyond Neptune. “Every time we take a picture,” says astronomer Surhud More, “there is a possibility that Planet Nine exists in the shot.” Yet, despite all the circumstantial evidence for its existence, no telescope has been able to spot it.

The first evidence for Planet Nine transpired in 2014, when astronomers discovered a handful of mini ice-worlds beyond the Kuiper belt following similar paths, writes Charlie Wood for Quanta Magazine. According to Scott Sheppard, an astronomer at the Carnegie Institution for Science, “if things are in the same orbit, then something’s pushing them.” Astronomical calculations predict that the light coming back from Planet Nine would appear more than 1 million times weaker, creating a “brick wall” to any sightings of it, according to astronomer Kevin Luhman. Teams led by Michael Brown at the California Institute of Technology, and Sheppard are searching for the planet with the Subaru telescope in Hawaii. Subaru’s wide field of view can sour a potential search area the size of 4,000 full moons. Still, factors like light pollution in the Milky Way, or the glare of a bright star can keep the planet hidden.

Some scientists are suggesting backup plans like searching for the heat glow emitted by the planet, which could be detected by current telescopes in Antarctica and Chile. Others wonder if signs of Planet Nine might lie buried in today’s data sets by just slightly affecting the paths of known planets. As astrophysicist Matthew Holman puts it, “if you put a planet in” the outer solar system, “the fit would be better.”

Scientists image exoplanet in process of formation

Direct observation of baby planets will provide scientists with new insight into poorly understood planet formation process.

Scientists have captured the first ever image of a baby exoplanet in the process of forming within the protoplanetary disk of gas and dust surrounding its parent star.

Using the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument on the European Southern Observatory’s (ESO) Very Large Telescope (VLT) in Chile, researchers obtained a clear image of the forming planet in orbit around the 5.4-million-year-old dwarf star PDS 70, approximately 370 light years from Earth.

SPHERE is an exoplanet-hunting instrument that acts as a coronagraph, which blocks the light of stars, enabling scientists to detect dim orbiting planets.

The newborn gas giant, known as PDS 70b, can be seen in the image as a bright point located to the right of the blocked-out star.

“These disks around young stars are the birthplaces of planets, but so far only a handful of observations have detected hints of baby planets in them,” said study leader Miriam Keppler of the Max Planck Institute for Astronomy in Heidelberg, Germany, in a public statement.

“The problem is that, until now, most of these planet candidates could just have been features in the disk.”

She and her colleagues photographed the forming planet after studying current and archival observations of the star via the VLT and an instrument at Hawaii’s Gemini Observatory.

According to the research team’s analysis, the planet is between two and three times larger than Jupiter and hotter than any planet in our solar system, with an estimated surface temperature of 1,800 degrees Fahrenheit (1,000 degrees Celsius).

Although it is extremely hot, PDS 70b orbits its star at a distance of 1.9 billion miles (three billion km), approximately the distance at which Uranus orbits our Sun.

Its high temperature is normal for a newborn gas giant even at such a great distance, as very young planets retain high levels of heat left over from their formation processes.

Observing a planet in the process of forming around a young star provide scientists with crucial insights into the planet formation process, noted Andre Muller, also of the Max Planck Institute for Astronomy, who led a second study on the star and planet.

“Kepler’s results give us a new window onto the complex and poorly understood early stages of planetary evolution,” he said.

Both Keppler’s study and Muller’s study have been published in the journal Astronomy and Astrophysics.

Ancient volcanoes formed Mars’s Medussae Fossae region

Volcanic eruptions could have warmed Mars enough for its surface to have supported liquid water.

Mars’s Medussae Fossae Formation, a region near the Martian equator composed of eroding sediments, may have been formed by ancient volcanic eruptions more than three billion years ago.

Composed of soft rock, this area, which was imaged by NASA’s Mars Reconnaissance Orbiter (MRO) in infrared wavelengths, is a massive region composed of ridges, valleys, and mesas. It has been described by NASA scientists as “an enigmatic pile of eroding sediments.”

First discovered during the 1960s by NASA’s Mariner spacecraft, Medussae Fossae and its exotic terrain and soft rock puzzled scientists, who were unable to determine whether it was created by wind, ice, water, or volcanoes.

Now, using MRO data, researchers at Johns Hopkins University in Baltimore measured the terrain’s density and found its porous surface to have likely been formed by explosive volcanic deposits rather than by ice deposits.

“The eruptions that created the deposit could have spewed massive amounts of climate-altering gases into Mars’s atmosphere and ejected enough water to cover Mars in a global ocean,” said Lujendra Ojha of Johns Hopkins University.

Medussaa Fossae is the largest known explosive volcanic deposit in the solar system, about 100 times more massive than the largest explosive volcanic deposit on Earth.

Gases emitted during the ancient eruptions could have warmed the planet enough for liquid water to have existed on the Red Planet’s surface. However, they also would have changed Mars’s atmosphere and surface by spewing hydrogen sulfide and sulfur dioxide, both of which are toxic gases.

Since the ancient eruptions, as much as half of the original rock at the site has eroded away, leaving behind the ridges and valleys.

“Future gravity surveys could help distinguish between ice, sediments, and igneous rocks in the upper crust of the planet,” noted Kevin Lewis, also of Johns Hopkins University.

Sedimentary rocks are deposited and solidify in layers and are usually transported by water and wind. Igneous rocks are formed when molten magma brought by volcanoes solidifies.

These findings are evidence that Mars’s interior is significantly more complex than scientists initially thought.

“Given the sheer magnitude of this deposit, it really is incredible because it implies that the magma was not only rich in volatiles and also that it had to be volatile-rich for long periods of time,” Ojha stated.

Findings of the study have been published in the Journal of Geophysical Research: Planets.