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PHYS

New method leads to discovery of extremely massive neutron star

Using an innovative method that yields higher accuracy than any previous one, a team of astronomers discovered one of the most massive neutron stars observed to date.

Also known as pulsars, neutron stars are the remnants of 10-30 solar-mass stars that died in supernova explosions. Although these stellar remnants are small in size, with diameters of about 12.4 miles (20 km), they are more massive than the Sun and thus very dense.

Researchers from the Astronomy and Astrophysics Group of the Universitat Politecnica de Catalunya (UPC) in Barcelona, Spain, and of the Canary Islands Institute of Astrophysics (IAC) found this particular neutron star, known as PSR J2215+5135, to have approximately 2.3 solar masses.

This makes it one of the most massive of the 2,000 plus neutron stars scientists have discovered.

PSR J2215+5135 is part of a close binary star system, for which the new method is aimed. Its companion is a Sun-like star, which the neutron star bombards with radiation.

Because the two stars orbit a common center of mass, known as a barycenter, the more massive the neutron star is, the faster the regular star moves.

With the new method, scientists use the spectral lines of hydrogen and magnesium in the companion star to measure the speed at which both sides of the companion star travel. By measuring the companion’s irradiated and non-irradiated sides, researchers can then determine the mass of the neutron star.

For the study, the research team used data collected by the Gran Telescopio Canarias (GTC), which is the world’s larges optical and infrared telescopes; the William Herschel Telescope (WHT); the Isaac Newton Telescope Group (ING), and the IAC-80 telescope, all located in Spain’s Canary Islands, as well as computer models of binary star systems with irradiation.

As a next step, scientists plan to use this method to measure the many similar neutron stars discovered within the last ten years as well as stellar mass black holes, which are also supernova remnants, and white dwarfs, the remnants of lower-mass stars, in binary systems.

A paper detailing the study has been published in the Astrophysical Journal.

 

 

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PHYS

Astronomers observing binary star system inadvertently discover exoplanet

Astronomers studying the young binary star system CS Cha inadvertently discovered a small, infant exoplanet in the dust disk surrounding the two stars.

Using the European Southern Observatory’s (ESO) adaptive optics Spectro-Polarimetric-High-Contrast Exoplanet REsearch  (SPHERE) instrument on the Very Large Telescope (VLT) in southern Chile, an international team of scientists led by Dutch researchers at Leiden University searched the disk surrounding the binary looking for evidence of new planets forming.

Located about 600 light years away in the southern hemisphere constellation Chameleon, the binary star system is only two to three million years old.

“The most exciting part is that the light of the (planet) companion is highly polarized. Such a preference in the direction of polarization usually occurs when light is scattered along the way. We suspect that the companion is surrounded by his own dust disc. The tricky part is that the disc blocks a large part of the light, and that is why we can hardly determine the mass of the companion. So it could be a brown dwarf but also a super-Jupiter in his toddler years. The classical planet-forming models can’t help us,” explained Christian Ginski of Leiden University and lead author of a study on the finding accepted for publication in the journal Astronomy and Astrophysics.

Brown dwarfs are considered the lowest end of the stellar classification system. If the suspected planet is actually a brown dwarf, then the CS Cha is a triple star system.

Developed in the Netherlands, SPHERE is capable of directly imaging exoplanets in dust disks surrounding stars by observing polarized light reflected by either the planets’ atmospheres or the dust disks.

In a distant orbit around the binary, the planet is located more than 214 times as far from the two stars as Earth is from the Sun.

After finding the planet in their images, the researchers looked at photos of the same system taken 19 years ago with the Hubble Space Telescope (HST) and 11 years ago with the VLT. They found the planet in both sets of images and successfully determined it moves with the double star system.

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PHYS

Changes in Ceres’ surface shows dwarf planet is geologically and chemically active

Now orbiting Ceres for three years, NASA’s Dawn spacecraft has detected changes in the dwarf planet’s surface during this time, along with a diversity of surface materials indicating Ceres is a geologically and chemically active world.

The probe’s observations of exposed deposits, especially ices, on Ceres’s surface, and its discovery of 12 sites on the small planet rich in sodium carbonates are the subjects of two separate studies published in the journal Science Advances.

Using its visible and infrared mapping spectrometer (VIR), Dawn discovered water ice at 12 separate sites on Ceres’s surface, with high concentrations in the northern wall of the 12-mile- (20-km-) wide Juling Crater.

Between April and October 2016, VIR detected an increase in ice in this crater wall.

Dawn has spent the last three years collecting data on Ceres’s geological, chemical, and geophysical conditions. Combining all this data gives mission scientists a comprehensive view of the dwarf planet, which was already found to have a 25-mile- (40-km-) wide crust composed of water and salts as well as possible organic compounds.

“This is the first detection of change on the surface of Ceres,” noted Andrea Raponi of the Institute of Astrophysics and Planetary Science in Rome, Italy, and lead author of the paper about water on the small planet’s surface.

“The combination of Ceres moving closer to the Sun in its orbit, along with seasonal change, triggers the release of water vapor from the subsurface, which then condenses on the cold crater wall. This causes an increase in the amount of exposed ice. The warming might also cause landslides on the crater walls that expose fresh ice patches,” Raponi explained.

The second paper, which focuses on the distribution of carbonates on Ceres’s surface, looks at several areas of a few square miles each where water is clearly present as part of the carbonate structure and identifies 12 areas with high sodium carbonate concentrations.

Led by Giacomo Carrozzo, also of the Institute of Astrophysics and Planetary Science, this study is the first ever to find hydrated carbonates on the surface of any planet or planetary body in the solar system.

Neither water ice nor hydrated carbonates are stable on Ceres’s surface in the long term unless they are buried. Over several million years, hydrated carbonates will dehydrate.

“This implies that the sites rich in hydrated carbonates have been exposed to recent activity on the surface,” Carrozzo said.

Because minerals containing water are widespread on Ceres, scientists believe the dwarf planet may once have had a subsurface ocean, some of which may still exist today.

Ceres’s diverse surface materials, along with its exposed areas and cryovolcanism, indicate its crust is not uniform, possibly due to the freezing of an underground ocean or other factors such as impacting objects and erupting cryovolcanoes.

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PHYS

ESA chooses three out of 25 mission proposals for concept studies

The European Space Agency (ESA) has selected three out of 25 mission proposals to advance for concept studies under its medium-class mission program.

Spanning various fields of astronomy and planetary studies, the chosen finalists include a high-energy survey of the early universe; an infrared observatory to study planets, stars, and galaxies; and a Venus orbiter.

Dubbed The Transient High Energy Sky and Early Universe Surveyor (Theseus), the first proposal seeks to monitor transient events in the entire universe across the whole sky since the Big Bang.  To that end, it will specifically focus on gamma ray bursts, extreme high-energy events resulting from supernovae that end the lives of massive stars.

Theseus will conduct a complete survey of all gamma ray bursts during the universe’s first billion years and accurately pinpoint their locations for future observation. It will also follow up on gravitational wave detections and identify the location of radiation produced by the events that triggered the gravitational waves.

To understand how the first stars and galaxies formed, the second project, known as the SPace Infrared telescope for Cosmology and Astrophysics (Spica) will look through clouds of dust surrounding newborn stars in infrared wavelengths.

A joint European-Japanese effort, Spica will use NASA’s Spitzer Space Telescope, the ESA’s Herschel Space Observatories, the James Webb Space Telescope (JWST), and the ground-based Atacama Large Millimeter/submillimeter Array (ALMA) with new far-infrared spectroscopic technology to study the birth processes of stars and galaxies.

EnVision, the third project selected for further study, will seek information as to why Venus evolved so differently than Earth in spite of the two being “sister planets” of roughly the same size. Following up on ESA’s Venus Express mission, which studied the planet’s atmosphere, EnVision will measure geological activity on Venus’s surface, map that surface, and obtain detailed radar maps to help scientists better understand the surface’s evolution.

The Venus orbiter will also explore the relationship between Venus’s atmosphere and geological activity on its surface.

“I am impressed about the quality and breadth of the missions proposed for M5 (the fifth medium-class mission in ESA’s Cosmic Vision science program). Each of the selected proposals has high scientific value, and would ensure a continuation of Europe’s expertise in the fields of planetary science, astrophysics, and cosmology,” said  ESA director of science Gunther Hasinger.

Just one of the three proposals will ultimately be selected, with the winner announced in 2021. The chosen mission will launch in 2032.

 

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PHYS

NASA mission will study solar wind in the outer solar system

A new NASA mission that will study the solar wind at the boundary between the outer solar system and interstellar space is set to launch in 2024.

The Interstellar Mapping and Acceleration Probe (IMAP), which will sample, analyze, and map the charged particles emitted by the Sun that make up the solar wind at the heliosphere, a magnetic bubble surrounding our solar system, was selected by NASA from a group of proposals submitted late last year subjected to a long peer review process.

Cost of the mission, minus that for the launch vehicle, is capped at $492 million. This fifth NASA Solar Terrestrial Probe (STP) will be project managed by the Johns Hopkins University Applied Physics Laboratory (JHUAPL) in Laurel, Maryland.

At the heliosphere, the solar wind collides with interstellar material in a process that limits the level of harmful radiation that passes the boundary into the solar system. IMAP will gather and analyze those particles that successfully cross that boundary.

“This boundary is where our Sun does a great deal to protect us. IMAP is critical to broadening our understanding of how this ‘cosmic filter’ works,” said deputy associate administrator for NASA’s Science Mission Directorate Dennis Andrucyk.

“The implications of this research could reach well beyond the consideration of Earthly impacts as we look to send humans into deep space.”

IMAP will also study how cosmic rays are generated in the heliosphere. These rays can originate both locally in the solar system and further out in the galaxy. Because they can harm both astronauts and electronic systems, understanding them is important for crewed deep space missions.

Cosmic rays are also believed to play a role in the generation of life.

To enable the best use of its instruments, IMAP will be placed in the first Lagrange point or L1 approximately one million miles (1.5 million km) from Earth in the direction of the Sun. Its instruments will monitor interaction between the solar wind and the interstellar medium.

David McComas of Princeton University will serve as the mission’s principal investigator.

 

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PHYS

New Horizons is awakened for KBO flyby

NASA’s New Horizons probe has been awakened from nearly six months in hibernation to begin preparations for its New Year’s Day 2019 flyby of Kuiper Belt Object (KBO) Ultima Thule (also known as 2014 MU69).

Mission Operations Manager Alice Bowman confirmed that a signal confirming the spacecraft had executed the necessary commands to emerge from hibernation was received at 2:12 AM on Tuesday, June 5, by mission headquarters at the Johns Hopkins University Applied Physics Laboratory (JHUAPL).

The radio signals were transmitted through NASA’s Deep Space Network (DSN).

Now close to 3.8 billion miles (6.1 billion km) from Earth, the spacecraft, which had been in hibernation mode since December 21, 2017, is in good health, and all its systems are back online, according to Bowman.

Traveling at the universal speed of light, radio signals take five hours and 40 minutes each way from Earth to the spacecraft and back.

Immediate tasks for the mission team involve collection of the spacecraft’s navigation tracking data via DSN. Over the next two months, computer commands preparing for the flyby will be uploaded to the probe. Science instruments and their subsystems will be tested, and Kuiper Belt data collected by the spacecraft is set to be retrieved and analyzed.

In late August, the first observations of the target KBO will be made using New Horizons‘ Long Range Reconnaissance Imager (LORRI). Mission scientists will use these sightings to refine New Horizons‘ trajectory toward its second target.

Currently, the spacecraft is about 162 million miles (262 million km) from Ultima Thule and traveling toward it at a speed of 760,200 miles (1,223,420 km) per day.

Since its historic July 2015 Pluto flyby, the probe has conducting distant studies of other Kuiper Belt Objects, including some dwarf planets, and of the heliosphere, the bubble-like region of space over which the Sun’s influence extends.

Ultima Thule is located approximately one billion miles (1.6 billion km) beyond Pluto. Readers can track New Horizons‘ position as it heads toward its target via the mission’s “Where is New Horizons?” web page.

The probe will now remain awake until late 2020, when all data from the Ultima Thule flyby as well as data from other Kuiper Belt science observations, is successfully transmitted back to Earth.

“Our team is already deep into planning and simulations of our upcoming flyby of Ultima Thule and excited that New Horizons is now back in an active state to ready the bird for flyby operations, which will begin in late August,” reported mission Principal  Investigator Alan Stern of the Southwest Research Institute (SwRI) in Boulder, Colorado.

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PHYS

“Tornadoes” on the Sun do not spin like those on Earth

Powerful, twisting structures observed on the Sun for about a century behave differently from tornadoes on Earth in that they do not spin or rotate, according to several new studies published in the journal Solar and Stellar Astrophysics and presented at the European Week of Astronomy and Space Science in Liverpool, England, this week.

Observed by NASA’s Solar Dynamics Observatory (SDO) satellite, these structures have temperatures as high as 3,600,000 degrees Fahrenheit (2,000,000 degrees Celsius) and are so large that they could devour multiple Earths.

Although they appear to be spinning in SDO images and in small movies made from those images, the new study confirms that such “spinning” is nothing more than an optical illusion, meaning solar tornadoes are not really tornadoes at all.

“We have yet to come up with a more appropriate name, though one could call them ‘oscillating pillars,'” Nicolas Labrosse of the University of Glasgow in Glasgow, Scotland, told the website IFLScience.

These solar structures cannot move because they are likely rooted beneath the solar corona. Their huge plumes are made up of magnetized superheated plasma, giving them an appearance resembling that of tornadoes on Earth.

The research teams came to their conclusion by using the Doppler effect to observe these structures. Waves of electromagnetic radiation, including visible light, become stretched when objects move away from us and compressed when they move toward us, in phenomena known as redshift and blueshift.

By measuring minute changes in celestial objects’ redshift and blueshift, astronomers can determine both the directions and velocities of these objects.

When the researchers calculated the Doppler effect of the twisting structures on the Sun, they discovered the structures are not moving except horizontally along magnetic field lines.

They appear tornado-like to us only due to our line of sight.

 

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PHYS

New advanced camera will directly image exoplanets

An international team of researchers has constructed the world’s largest and most advanced superconducting camera, which will be attached to the 200-inch(5.1-meter) Hale Telescope at Palomar Observatory in California to directly image exoplanets.

Titled the Dark-speckle Near-infrared Energy-resolved Superconducting Spectrophotometer (DARKNESS), the camera will use Microwave Kinetic Inductance Detectors along with a system of adaptive optics to capture images.

“Taking a picture of an exoplanet is extremely challenging because the star is much brighter than the planet, and the planet is very close to the star,” explained research team leader Benjamin Mazin of UC Santa Barbara and Worster Chair in Experimental Physics at UCSB.

Most exoplanet detection methods do not involve direct imaging and instead find planets orbiting other stars through indirect methods, such as measuring the dimming of light when a planet passes in front of the star.

Designed to get around the difficulties of directly imaging planets, DARKNESS has unique capabilities, such as the ability to determine the wavelength and arrival time of individual photons, a technique crucial for differentiating between light coming from a planet and scattered or reflected light from other sources.

“This technology will lower the contrast floor, so that we can detect fainter planets,” Mazin emphasized. “We hope to approach the photon noise limit, which will give us contrast ratios close to 10 to the minus eight, allowing us to see planets 100 million times fainter than the star. At those contrast levels, we can see some planets in reflected light, which opens up a whole new domain of planets to explore. The really exciting thing is that this is a technology pathfinder for the next generation of telescopes.”

When it is attached to the Hale Telescope, DARKNESS will be able to overcome atmospheric distortion with a technique that suppresses starlight, allowing the observation of greater contrast ratios between stars and their orbiting planets.

The camera will do this via its ability to quickly measure light and signal back to a rubber mirror capable of forming into new shapes at a rate of 2,000 times per second.

Over the last year-and-a-half, the research team has concentrated on working out bugs during four separate trials in which they attached DARKNESS to the Hale Telescope.

Next month, they will work on collecting more data on individual planets.

In the long term, scientists hope to attach DARKNESS to the Thirty Meter Telescope (TMT), which will be built either on Mauna Kea, Hawaii, or in the Canary Islands in Spain.

“With that, we’ll be able to take pictures of planets in the habitable zones of nearby low-mass stars and look for life in their atmospheres,” Mazin noted.

A paper on the camera and its capabilities has been published in the journal Publications of the Astronomical Society of the Pacific.

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NWT_Earth

Earth’s oldest rocks may have been created by asteroid impacts

Earth’s oldest evolved rocks, found in part of the Acasta Gneiss Complex in northwestern Canada, have compositions different from those that make up the planet’s ancient continental crust, suggesting the former were created in a different process, possibly through asteroid impacts on early Earth’s crust.

During the eras known as Earth’s Hadean and early Archeon epochs, between 4.5 billion and 3.9 billion years ago, the solar system was a much more violent place. Many asteroids likely hit the Earth during this period, melting surface rocks and recycling them in the process, noted researchers at Australia’s Curtin University, who conducted a study on the subject.

Led by Tim Johnson of Curtin University’s School of Earth and Planetary Sciences, a research team used computer models to illustrate the partial melting of iron-rich basaltic rocks caused by impacting asteroids.

“The melting of these rocks at such shallow levels is most easily explained by meteorite impacts, which would have supplied the energy to attain the extreme temperatures required for melting,” Johnson said.

“Our computer simulations of asteroid impacts show that not only is this scenario physically plausible, but the region of shallow melting needed to form these ancient evolved rocks would have been widespread. Given the predicted high flux of meteorites about four billion years ago, impact melting may have been the predominant mechanism that generated granitic rocks at that time.”

Granite is an igeneous rock that forms from the slow crystallizing of subsurface magma. Created from the cooling and solidifying of molten material, igneous rock can form both on and/or below Earth’s surface.

Phil Bland, also of Curtin University’s School of Earth and Planetary Sciences, noted that almost no four-billion-year-old rocks are found on Earth because the numerous asteroid impacts at that time caused those rocks to melt and subsequently be recycled.

“The only known rocks from the Hadean eon are those in northwest Canada, which have chemical compositions clearly distinct from those that dominate ancient continental crust worldwide, suggesting they were formed in a different way,” Bland stated.

A paper on the study has been published in the journal Nature Geoscience.

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NWT_Environment SCI

Antarctic iceberg melting near Earth’s equator

The largest iceberg to ever break off of Antarctica’s Ross Ice Shelf has spent the last 18 years migrating away from its home and is melting away as it approaches Earth’s equator.

After breaking away from the ice shelf in 2000, the iceberg, designated B-15, which initially measured 20 nautical miles wide and 160 nautical miles long, or a total of 3,200 square nautical miles, was driven three-quarters of the way around Antarctica by currents before heading north into the southern Atlantic Ocean sometime during the last two years.

Over time, many smaller pieces have broken off the iceberg and melted away. Just four ice chunks with surface areas large enough to be observed by the National Ice Center (NIC)–20 square nautical miles or larger–remain today.

Images of B-15 taken from the International Space Station (ISS) confirm the iceberg, which has traveled 6,600 miles (10,000 km) from its ice shelf, is now northwest of the South Georgia Islands and heading toward the southern end of South America in the direction of the equator.

One of the four ice chunks, labeled B-15Z, has a surface area of 50 square nautical miles. Drifting toward the equator, it now has a large crack at its center, and pieces of ice can be seen breaking away from its edges.

All of B-15’s chunks will likely melt as warm tropical waters “work [their] way through the iceberg like a set of knives,” noted NASA glaciologist Kelly Brunt.

Icebergs that make their way into this region generally melt very rapidly.

Climate change is believed to be responsible for the breakaway of B-15 and other icebergs from larger ice shelves around the world.