Month: December 2017

Indonesia’s Sinabung Volcano Erupts Again

JAKARTA – Indonesia’s Sinabung volcano in northern Sumatra province erupted again on Wednesday (Dec 27), sending hot clouds into the sky.

The eruption occurred at 3.36pm local time, the country’s disaster management agency (BNPB) spokesman Sutopo Purwo Nugroho said in an update on his Twitter account.

The eruption sent black gray volcanic ash up into the sky as high as 3,500m towards the east and south-east and 4,600m in the south and south-east direction.

Volcanic ash also fell on several villages around the volcano, he said.

There were no casualties from Wednesday’s eruption as those living within the red zone around the volcano had been evacuated, he added.

“Mount Sinabung’s continuous eruptions have caused the exclusion zone to expand,” Dr Sutopo said, adding that 3,331 families who live in areas prone to the impact from the eruptions must be evacuated.

“Residents need to stay alert and listen to the government’s recommendations. We cannot predict when Mount Sinabung will stop erupting. Mount Sinabung’s volcanic and seismic parameters are still high therefore future eruptions are still likely.”

The eruption on Wednesday followed another on Dec 18.

The Indonesian authorities have imposed the highest alert on the volcano, which has been in place since 2013 when it began erupting.

Scientists Describe How Solar System Could Have Formed In Bubble Around Giant Star

Despite the many impressive discoveries humans have made about the universe, scientists are still unsure about the birth story of our solar system.

Scientists with the University of Chicago have laid out a comprehensive theory for how our solar system could have formed in the wind-blown bubbles around a giant, long-dead star. Published Dec. 22 in the Astrophysical Journal, the study addresses a nagging cosmic mystery about the abundance of two elements in our solar system compared to the rest of the galaxy.

The general prevailing theory is that our solar system formed billions of years ago near a supernova. But the new scenario instead begins with a giant type of star called a Wolf-Rayet star, which is more than 40 to 50 times the size of our own sun. They burn the hottest of all stars, producing tons of elements which are flung off the surface in an intense stellar wind. As the Wolf-Rayet star sheds its mass, the stellar wind plows through the material that was around it, forming a bubble structure with a dense shell.

“The shell of such a bubble is a good place to produce stars,” because dust and gas become trapped inside where they can condense into stars, said coauthor Nicolas Dauphas, professor in the Department of Geophysical Sciences. The authors estimate that 1 percent to 16 percent of all sun-like stars could be formed in such stellar nurseries.

This setup differs from the supernova hypothesis in order to make sense of two isotopes that occur in strange proportions in the early solar system, compared to the rest of the galaxy. Meteorites left over from the early solar system tell us there was a lot of aluminium-26. In addition, studies, including a 2015 one by Dauphas and a former student, increasingly suggest we had less of the isotope iron-60.

This brings scientists up short, because supernovae produce both isotopes. “It begs the question of why one was injected into the solar system and the other was not,” said coauthor Vikram Dwarkadas, a research associate professor in Astronomy and Astrophysics.

This brought them to Wolf-Rayet stars, which release lots of aluminium-26, but no iron-60.

“The idea is that aluminum-26 flung from the Wolf-Rayet star is carried outwards on grains of dust formed around the star. These grains have enough momentum to punch through one side of the shell, where they are mostly destroyed — trapping the aluminum inside the shell,” Dwarkadas said. Eventually, part of the shell collapses inward due to gravity, forming our solar system.

As for the fate of the giant Wolf-Rayet star that sheltered us: Its life ended long ago, likely in a supernova explosion or a direct collapse to a black hole. A direct collapse to a black hole would produce little iron-60; if it was a supernova, the iron-60 created in the explosion may not have penetrated the bubble walls, or was distributed unequally.

Other authors on the paper included UChicago undergraduate student Peter Boyajian and Michael Bojazi and Brad Meyer of Clemson University.

Indonesia’s Bali Volcano Spews Thick Smoke, Ashes

The Sunday’s eruption took place at 10:05 a.m. local time, emitting grayish thick smoke with wind detected heading for northeast, Indonesian National Disaster Mitigation Agency (BNPB) said.

“The eruption lasted for 10 minutes. White smoke was seen came out from the volcano summit after the blast,” BNPB Spokesperson Sutopo Purwo Nugroho said in a statement on Sunday.

He added that volcanic activities in the volcano remained intense at present.

Indonesian authorities imposed highest alert status on the volcano which took into effect since Nov. 27.

Sutopo pointed out that no significant impact has occurred in the last two consecutive days.

“Daily activities were normal in Bali, people remained calm. They currently have enough knowledge on impacts from the volcano’s eruption,” Sutopo added.

The top alert status was only applied within 8 to 10 kilometers from the volcano summit. People were told to refrain from conducting any activities around those areas.

“Outside those areas were still normal and safe,” he said.

The eruption which occurred on Saturday on 11:57 a.m. had prompted rain of ashes in villages located in the slope of the volcano.

Indonesian Transportation Minister Budi Karya Sumadi said on Saturday that the eruption would not affect the airports in Bali and nearby island of Lombok as the wind was heading for the east.

The ministry did not issue Notam (Notice to Airmen) related to the latest volcano eruption. The Notam notification contains information related to flight sustainability in emergency situation.

Volcanic activities of Mount Agung have been ensuing since September after 54 years of inactivity. The volcanic event has severely battered Bali’s tourism since then.

‘Cosmic Lantern’ Could Help Us Further Understand The Fate Of The Universe

New research has provided a deeper insight into emission line galaxies, used in several ongoing and upcoming surveys, to help us further understand the composition and fate of the Universe.

The quest to determine the nature of both dark matter and dark energy has led scientists to adopt new tracers of the large-scale structure of the Universe, such as emission line galaxies. These galaxies present strong emission lines from the gas heated up by newly formed stars.

Lead author of the study, Dr Violeta Gonzalez-Perez from the University of Portsmouth’s Institute of Cosmology and Gravitation, said: “Galaxies are cosmic lanterns that show small patches of cosmic history, informing us of the changes in the space-time fabric of the Universe. The strong formation of new stars in galaxies leave a characteristic imprint in their spectra that allows for a precise determination of their distance.

“Moreover, as young stars are very bright, galaxies with a strong star formation can be visible further back in cosmic time. These are the two characteristics that make emission line galaxies excellent cosmological tracers for a long time span.”

However, current emission line galaxy samples are small and their characteristics are not well understood. Computational modelling is the only way to attempt to understand all the processes involved in the formation and evolution of these galaxies.

Astronomers from the University of Portsmouth’s world-leading Institute of Cosmology and Gravitation (ICG) explored the characteristics of emission line galaxies through experiments on DiRAC’s (Distributed Research utilising Advanced Computing) national supercomputing facility at Durham University.

The computational experiments were concentrated around the time when the Universe went from being matter dominated to becoming dark energy dominated as it is now. They found that most emission line galaxies live at the centres of gravitational potential wells, with masses equivalent to eleven billion of our suns. Current numerical models of formation and evolution of galaxies also show that emission line galaxies trace the underlying gravitational potentials in a different way to galaxies selected by their stellar mass.

They then compared their results with the expectations from the SDSS-IV/eBOSS surveys and Dark Energy Spectroscopic Instrument (DESI). Both surveys aim to measure the effect of dark energy on the expansion of the Universe.

Dr Gonzalez-Perez said: “This comparison will improve our understanding of galaxy formation and evolution and allow scientists to benefit from a more realistic model for the mechanisms that produce emission line galaxies.”

Next summer, the SDSS-IV/eBOSS survey is expected to have the first cosmological results from these tracers. In the coming years, the Dark Energy Survey Instrument (DESI) will expand this usage of emission line galaxies as cosmological tracers. The DESI will see their first light in 2019 and it will measure the spectra of 35 million galaxies, which is eight times more than the current SDSS has proved. In 2021, Euclid will start collecting spectra for 50 million sources, solely focusing on emission line galaxies. The ICG is involved in both surveys.

Star In The Constellation Pisces Is ‘Eating’ Planets

Like the ancient Greek god Cronus who devoured his children, a star 550 light years from Earth has been discovered to be slowly consuming its “offspring” — crushing one or more planets in its orbit into vast clouds of gas and dust.

The discovery that RZ Piscium — located in the constellation Pisces — is an insatiable “eater of worlds” was reported today in The Astronomical Journal. Indiana University astronomer Catherine Pilachowski is co-author on the study, titled “Is the Young Star RZ Piscium Consuming Its Own (Planetary) Offspring?”

The discovery may shed light on a brief but volatile period in the history of many solar systems, including our own.

“We know it’s not uncommon for planets to migrate inward in young solar systems since we’ve found so many solar systems with ‘hot Jupiters’ — gaseous planets similar in size to Jupiter but orbiting very close to their stars,” said Pilachowski, who is the Daniel Kirkwood Chair in the IU Bloomington College of Arts and Sciences’ Department of Astronomy. “This is a very interesting phase in the evolution of planetary systems, and we’re lucky to catch a solar system in the middle of the process since it happens so quickly compared to the lifetimes of stars.”

Doomed worlds that fly too close to their sun — only to be ripped apart by its tidal forces — are officially known as “disrupted planets.” In the case of RZ Piscium, the material near the sun-like star is being slowly pulled apart to create a small circle of debris about the same distance from the star as the planet Mercury’s orbit is from our sun.

“Based on our observations, it seems either that we’re seeing a fairly massive, gaseous planet being pulled apart by the star, or perhaps two gas-rich planets that have collided and been torn apart,” Pilachowski said of RZ Piscium.

Even solar systems whose planets are not lost to their sun are unstable in their early history, since newly born planets interact strongly with one another — as well as their sun — through gravity, she added. In our solar system, for example, some astronomers speculate that Uranus and Neptune swapped orbits about 4 billion years ago. But erratic orbits tend to stabilize over time, falling into regular patterns.

An expert on the analysis of light spectrum from distant stars to determine their temperature, gravity and elemental composition, Pilachowski was responsible in the new study for determining the gravitational strength near RZ Piscium’s surface. The observation helped shed light on the star’s radius and brightness, both of which suggest a young star in the midst of a freewheeling solar system with unstable planets.

This is significant because RZ Piscium’s age was uncertain. The debris field around a star can result from either the erratic orbits in young solar systems or the destruction of planets that occurs as an old star grows before collapsing and dying.

Pilachowski’s analysis of the star’s light also helped determine the amount of lithium in the star, marking the star as a relatively young 30 million to 50 million years. Astronomers can use lithium levels to estimate a star’s age because the element declines over time.

The study’s authors also found the star’s temperature to be about 9,600 degrees Fahrenheit (5,330 degrees Celsius) — only slightly cooler than our sun’s. Another sign of the star’s relative youth: It produces X-rays at a rate roughly 1,000 times greater than our sun.

“This discovery really gives us a rare and beautiful glimpse into what happens to many newly formed planets that don’t survive the early dynamical chaos of young solar systems,” Pilachowski said. “It helps us understand why some young solar systems survive — and some don’t.”

Astronomers shed Light On Formation Of Black Holes And Galaxies

Stars forming in galaxies appear to be influenced by the supermassive black hole at the center of the galaxy, but the mechanism of how that happens has not been clear to astronomers until now.

“Supermassive black holes are captivating,” says lead author Shelley Wright, a University of California San Diego Professor of Physics. “Understanding why and how galaxies are affected by their supermassive black holes is an outstanding puzzle in their formation.”

In a study published today in The Astrophysical Journal, Wright, graduate student Andrey Vayner, and their colleagues examined the energetics surrounding the powerful winds generated by the bright, vigorous supermassive black hole (known as a “quasar”) at the center of the 3C 298 host galaxy, located approximately 9.3 billion light years away.

“We study supermassive black holes in the very early universe when they are actively growing by accreting massive amounts of gaseous material,” says Wright. “While black holes themselves do not emit light, the gaseous material they chew on is heated to extreme temperatures, making them the most luminous objects in the universe.”

The UC San Diego team’s research revealed that the winds blow out through the entire galaxy and impact the growth of stars.

“This is remarkable that the supermassive black hole is able to impact stars forming at such large distances,” says Wright.

Today, neighboring galaxies show that the galaxy mass is tightly correlated with the supermassive black hole mass. Wright’s and Vayner’s research indicates that 3C 298 does not fall within this normal scaling relationship between nearby galaxies and the supermassive black holes that lurk at their center. But, in the early universe, their study shows that the 3C 298 galaxy is 100 times less massive than it should be given its behemoth supermassive black hole mass.

This implies that the supermassive black hole mass is established well before the galaxy, and potentially the energetics from the quasar are capable of controlling the growth of the galaxy.

To conduct the study, the UC San Diego researchers utilized multiple state-of-the-art astronomical facilities. The first of these was Keck Observatory’s instrument OSIRIS (OH-Suppressing Infrared Imaging Spectrograph) and its advanced adaptive optics (AO) system. An AO system allows ground-based telescopes to achieve higher quality images by correcting for the blurring caused by the Earth’s atmosphere. The resulting images are as good as those obtained from space.

The second major facility was the Atacama Large Millimeter/submillimeter Array, known as “ALMA,” an international observatory in Chile that is able to detect millimeter wavelengths using up to 66 antennae to achieve high-resolution images of the gas surrounding the quasar.

“The most enjoyable part of researching this galaxy has been putting together all the data from different wavelengths and techniques,” said Vayner. “Each new dataset that we obtained on this galaxy answered one question and helped us put some of the pieces of the puzzle together. However, at the same time, it created new questions about the nature of galaxy and supermassive black hole formation.”

Wright agreed, saying that the data sets were “tremendously gorgeous” from both Keck Observatory and ALMA, offering a wealth of new information about the universe.

These findings are the first results from a larger survey of distant quasars and their energetics’ impact on star formation and galaxy growth. Vayner and the team will continue developing results on more distant quasars using the new facilities and capabilities from Keck Observatory and ALMA.

Cosmic Filament Probes Our Galaxy’s Giant Black Hole

The center of our Galaxy has been intensely studied for many years, but it still harbors surprises for scientists. A snake-like structure lurking near our galaxy’s supermassive black hole is the latest discovery to tantalize astronomers.

In 2016, Farhad Yusef-Zadeh of Northwestern University reported the discovery of an unusual filament near the center of the Milky Way Galaxy using the NSF’s Karl G. Jansky Very Large Array (VLA). The filament is about 2.3 light years long and curves around to point at the supermassive black hole, called Sagittarius A* (Sgr A*), located in the Galactic center.

Now, another team of astronomers has employed a pioneering technique to produce the highest-quality image yet obtained of this curved object.

“With our improved image, we can now follow this filament much closer to the Galaxy’s central black hole, and it is now close enough to indicate to us that it must originate there,” said Mark Morris of the University of California, Los Angeles, who led the study. “However, we still have more work to do to find out what the true nature of this filament is.”

The researchers have considered three main explanations for the filament. The first is that it is caused by high-speed particles kicked away from the supermassive black hole. A spinning black hole coupled with gas spiraling inwards can produce a rotating, vertical tower of magnetic field that approaches or even threads the event horizon, the point of no return for infalling matter. Within this tower, particles would be sped up and produce radio emission as they spiral around magnetic field lines and stream away from the black hole.

The second, more fantastic, possibility is that the filament is a cosmic string, theoretical, as-yet undetected objects that are long, extremely thin objects that carry mass and electric currents. Previously, theorists had predicted that cosmic strings, if they exist, would migrate to the centers of galaxies. If the string moves close enough to the central black hole it might be captured once a portion of the string crosses the event horizon.

The final option is that the position and the direction of the filament aligning with the black hole are merely coincidental superpositions, and there is no real association between the two. This would imply it is like dozens of other known filaments found farther away from the center of the Galaxy. However, such a coincidence is quite unlikely to happen by chance.

“Part of the thrill of science is stumbling across a mystery that is not easy to solve,” said co-author Jun-Hui Zhao of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. “While we don’t have the answer yet, the path to finding it is fascinating. This result is motivating astronomers to build next generation radio telescopes with cutting edge technology.”

Each of the scenarios being investigated would provide intriguing insight if proven true. For example, if the filament is caused by particles being ejected by Sgr A*, this would reveal important information about the magnetic field in this special environment, showing that it is smooth and orderly rather than chaotic.

The second option, the cosmic string, would provide the first evidence for a highly speculative idea with profound implications for understanding gravity, space-time and the Universe itself.

Evidence for the idea that particles are being magnetically kicked away from the black hole would come from observing that particles further away from Sgr A* are less energetic than those close in. A test for the cosmic string idea will capitalize on the prediction by theorists that the string should move at a high fraction of the speed of light. Follow-up observations with the VLA should be able to detect the corresponding shift in position of the filament.

Even if the filament is not physically tied to Sgr A*, the bend in the shape of this filament is still unusual. The bend coincides with, and could be caused by, a shock wave, akin to a sonic boom, where the blast wave from an exploded star is colliding with the powerful winds blowing away from massive stars surrounding the central black hole.

“We will keep hunting until we have a solid explanation for this object,” said co-author Miller Goss, from the National Radio Astronomy Observatory in Socorro, New Mexico. “And we are aiming to next produce even better, more revealing images.”