Young Star HD 95086: Two dust belts surrounded by a large dust halo

An artist's impression of a young star surrounded by debris rings and a vast dust halo. 

Credit: NASA/JPL-Caltech

Scientists at the University of Arizona have discovered what might be the closest thing to "baby photos" of our solar system.

A young star called HD 95086 is found to have two dust belts, analogous to the asteroid and Kuiper belts in the Solar System, surrounded by a large dust halo that only young planetary systems have.

Similar dust structures are also found around another, slightly older star called HR 8799, where four massive planets occupy the large gap between the two belts.

HR 8799, the first star found to host four directly imaged planets, is often referred to as a younger and scaled-up version of our Solar System.

Finding another star similar to HR 8799 suggests a common model for how stars form planets and how their planetary systems evolve.

The ages of these systems span an interesting period, about 10 to 90 million years, when terrestrial planets form and giant planets settle down to their final configuration in our own Solar System, the team reports.

"We think HD 95086 is a snapshot of what our solar system might have looked like when it was only 10 to 20 million years old," said Kate Y.L.Su, an associate astronomer in the UA's Department of Astronomy and Steward Observatory and lead author of the paper.

Using data from NASA's Spitzer Space Telescope and ESA's Herschel Space Observatory combined with detailed simulations, the researchers found HD 95086 and HR 8799 each have a vast disk halo of fine dust, suggesting enhanced collisional activities in their Kuiper-belt-like belts.

This is an expected behavior for systems that are experiencing dynamical settling of gas giants and possibly late formation of giant ice planets.

A schematic view of the HD 95086 system. Credit: NASA/JPL-Caltech

The large gap between the warm and cold belts in HD 95086, HR 8799 and some other nearby older systems like debris disk twins Vega and Fomalhaut is an excellent signpost for multiple, yet-to-be-discovered planets, according to the research team.

HD 95086 and HR 8799 are located 295 and 129 light years from Earth in the constellations of Carina and Pegasus, respectively.

"The HD 95086 system with its a young star hosting at least one planet of about five Jupiter masses along with massive asteroid and Kuiper-like debris belts is a promising target for planet hunting,"

Su said. "Both systems are very similar, except the HD 95086 has more dust, which is in line with theories of planet formation and leads us to believe it is the younger of the two. By looking at other systems like these we can piece out how our solar system came to be."

"There have to be more planets than have been discovered to make a gap that is this big," said Sarah Morrison, a co-author of the paper and a PhD student in the UA's Department of Planetary Sciences who ran computer models to constrain the possibilities of how many planets are likely to inhabit the system, what their masses could be like and where their orbits could be.

"We think that the system is a prime candidate for direct imaging campaigns to find those planets."

The origin of Uranus and Neptune elucidated?

Uranus and Neptune as seen from NASA's Voyager mission. Credit: NASA

A team of French-American researchers led by the UTINAM Institute (CNRS/Université de Franche-Comté) has just proposed a solution to the problematic chemical composition of Uranus and Neptune, thus providing clues for understanding their formation.

The researchers focused on the positioning of these two outermost planets of the Solar System, and propose a new model explaining how and where they formed.

Their results have been published in The Astrophysical Journal on September 20.

Uranus and Neptune, the outermost planets in the Solar System, each have a mass approximately fifteen times that of the Earth, consisting of up to 90% ice, and highly enriched in carbon.

Because of these particular characteristics, the origin of the two planets remains unresolved today.

Earlier models for their formation, as well as observations of the outer Solar System, could not explain how they formed in the area where they are found today.

This area, which is located very far from the Sun, did not contain sufficient building blocks to form Uranus and Neptune quickly enough before the dissipation of the protosolar nebula.

Once the nebula dissipated, it became impossible for the two planets to accrete gaseous envelopes.

The ESA Herschel Space Observatory recently focused on the isotopic composition of Uranus and Neptune, and especially on the deuterium-to-hydrogen ratio (D/H), a tracer used in planetology to examine the origin of the elements that formed the Solar System.

This isotopic ratio is very sensitive to the temperature of the protosolar nebula, being low close to the Sun, and increasing with the distance.

Dynamic models suggest that Uranus and Neptune formed in the same distant region as the comets, and should therefore have a high D/H ratio.

Surprisingly though, the Herschel measurements show that the D/H ratio in the two planets is much lower than that measured in comets.

This study solves all of these problems at once, by proposing a new model based on detailed simulations of the distribution and transport of the most abundant volatile elements in the Solar System's protosolar nebula (H2O, CO and N2).

These simulations show the presence of density "peaks" of solids in regions where nebular temperature is low enough for gas condensation (or ice lines).

The results show that Uranus and Neptune apparently formed on the Carbon Monoxide (CO) ice line, which would explain why they consist of carbon-rich solids but nitrogen-depleted gas.

Accretion of large quantities of CO with low quantities of cometary H2O gives the D/H value measured in the atmosphere of these planets.

Moreover, since the nitrogen ice line is located slightly farther away, the planets formed naturally poor in nitrogen..

The proposed model gives carbon and nitrogen abundances that are consistent with observed values, and establishes that the formation of Uranus and Neptune took place in this distant region.

More information: "The Measured Compositions of Uranus and Neptune from their Formation on the CO Ice Line," Mohamad Ali-Dib, Olivier Mousis, Jean-Marc Petit and Jonathan I. Lunine, Astrophysical Journal, Vol. 793, Issue 1, September 2014. Arxiv.org/abs/1407.2568

NASA Cassini: MIPT researcher models Titan's atmosphere

Titan’s atmosphere. Image from the Cassini orbiter.

Credit: Nasa

A researcher from Moscow Institute of Physics and Technology (MIPT), Prof. Vladimir Krasnopolsky, who heads the Laboratory of High Resolution Infrared Spectroscopy of Planetary Atmospheres, has published the results of the comparison of his model of Titan's atmosphere with the latest data.

Vladimir Krasnopolsky

The article in the journal Icarus compares the chemical composition of Titan's atmosphere with parameters predicted by a mathematical model.

The atmosphere of Saturn's largest moon, Titan, was described by a model that took into account the presence of 83 neutral molecules, 33 ions and 420 different chemical reactions between them.

Despite the fact that Titan is located much further from the Sun than the Earth and that radiation flux coming from the Sun to the moon is 100 times lower, the intensity of UV rays is enough to spur photochemical reactions in the upper layers of Titan's atmosphere.

Cassini orbiter

The data regarding the composition of Titan's atmosphere, which is 1.6 times denser near the surface than the Earth's air, was obtained from several sources, mainly the Cassini orbiter.

It was equipped with a number of gauges, including ultraviolet and infrared spectrometers and equipment for studying the ions that were drawn into space.

Within ten years in Saturn's orbit, a plasma complex and a mass spectrometer designed specifically for this research project gathered enough data to compare it with mathematical models.

IRAM ground submillimeter telescope

In addition to Cassini, part of the data was obtained using the IRAM ground submillimeter telescope and the Hershel infrared space observatory.

Data on the distribution of aerosol particles in Titan's atmosphere was received from a unique space capsule, Huygens, which landed on Titan for the first time in the history of mankind and sent the first photos of its surface.

Comparing this data with the previously developed model, Krasnopolsky showed that the theoretical description of Titan's atmosphere matches the reality quite accurately.

There are discrepancies, however, but they are caused by inevitable measurement errors – so far, the concentrations of many substances are approximate.

The most important thing is not the absolute matching of specific parameters but the correctness of the general model of chemical processes.

"The coherence of the model with reality means that we can correctly tell where different substances go from Titan's ionosphere and where they come from," Krasnopolsky said.

Krasnopolsky is considered a leading global expert on the atmosphere of celestial bodies of the solar system.

He has participated in the creation of spectrometers for a variety of spacecraft, including the legendary Voyagers and the first Soviet interplanetary probes.

Black hole fireworks in nearby galaxy Messier 106

A galaxy about 23 million light-years away is the site of impressive, ongoing, fireworks. 

Rather than paper, powder, and fire, this galactic light show involves a giant black hole, shock waves, and vast reservoirs of gas. 

Credit: NASA /CXC /JPL-Caltech /STScI /NSF /NRAO /VLA

Celebrants this Fourth of July will enjoy the dazzling lights and booming shock waves from the explosions of fireworks.

A similarly styled event is taking place in the galaxy Messier 106 (NGC 4258), as seen by NASA's Spitzer Space Telescope, Chandra X-ray Observatory and the Herschel Space Observatory. Herschel is a European Space Agency mission with important NASA contributions.

Energetic jets, which blast from Messier 106's central black hole, are heating up material in the galaxy and thus making it glow, like the ingredients in a firework.

The jets also power shock waves that are driving gases out of the galaxy's interior.

Those gases constitute the fuel for churning out new stars. A new study estimates the shock waves have already warmed and ejected two-thirds of the gas from the center of Messier 106.

With a reduced ability to birth new stars, Messier 106 appears to be transitioning into a barren, so-called lenticular galaxy full of old, red stars. Lenticular galaxies are flat disks without prominent spiral arms.

"Jets from the supermassive black hole at the center of Messier 106 are having a profound influence on the available gas for making stars in this galaxy," said Patrick Ogle, an astrophysicist at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, and lead author of a new paper describing the results.

"This process may eventually transform the spiral galaxy Messier 106 into a lenticular galaxy, depriving it of the raw material to form stars."

Many galaxies contain a central black hole that actively "feeds" upon nearby gas.

Some of the material, as it draws toward the black hole, dramatically speeds up and violently spews out as twin jets near the black hole's poles.

As one of the Milky Way's closest galactic neighbors, Messier 106 offers a great opportunity for investigating these high-powered jets.

Messier 106 is 23.5 million light-years distant, and visible with binoculars in the constellation Canes Venatici.

For the new study, researchers used data obtained with the Spitzer infrared telescope before the observatory ran out of coolant in 2009, as planned.

The data amount to a map of the infrared light emitted by heated-up hydrogen molecules in Messier 106.

The warmed hydrogen is a signature of the jet from the central black hole energizing the surrounding disk of the galaxy.

Herschel Space Observatory uncovers a weird ring of dusty material

Image credit: ESA/NASA/JPL-Caltech/Whitman College

The Herschel Space Observatory has uncovered a weird ring of dusty material while obtaining one of the sharpest scans to date of a huge cloud of gas and dust, called NGC 7538.

The gigantic ring structure is situated at the center-top of this image.

The odd ovoid possesses the mass of 500 suns, with its long axis spanning about 35 light-years and its short axis about 25 light-years.

Astronomers often see ring and bubble-like structures in cosmic dust clouds.

The strong winds cast out by the most massive stars, called O-type stars, can generate these expanding puffs, as can their explosive deaths as supernovas but no energetic source or remnant of a deceased O-type star, such as a neutron star, is apparent within the center of the ring.

It is possible that a big star blew the bubble and, because stars are all in motion, subsequently left the scene, escaping detection.

Astronomers study stellar nurseries such as NGC 7538 to better learn how stars come into being. The Herschel observations have revealed numerous clumps of material in NGC 7538, a baker's dozen of which may evolve into O-type stars.

Early in the star-formation process, these clumps remain quite cold, just a few tens of degrees above absolute zero.

At these temperatures, the clumps emit the bulk of their radiation in the low-energy, submillimeter and infrared light that Herschel was specifically designed to detect.

Finding the mysterious ring came as an unexpected bonus during the Herschel observing run.

The blue and green colours in this image represent 70- and 160-micron data, respectively, from Herschel's Photoconductor Array Camera and Spectrometer (PACS) instrument.

The red colours are 250-micron observations obtained from Herschel's Spectral and Photometric Imaging Receiver (SPIRE) instrument.

Herschel’s population of trans-Neptunian objects

Herschel’s population of trans-Neptunian objects.

Credit: ESA

ESA’s Herschel space observatory has observed 132 of the known 1400 cold worlds that inhabit a region of the Solar System beyond the orbit of Neptune, some 4.5–7.5 billion km from the Sun.

These ‘trans-Neptunian objects’ (TNOs), include worlds such as Pluto, Eris, Haumea and Makemake, and make up a vast population of such objects thought to occupy these far-flung reaches of the Solar System.

TNOs are particularly cold, at around –230ºC, but these low temperatures lend themselves to observations by Herschel, which observes at far-infrared to sub-millimetre wavelengths.

Indeed, the space observatory observed the thermal emission from 132 such objects during its nearly four-year lifetime.

These measurements provided their sizes and albedos (the fraction of visible light reflected from the surface), properties that are not otherwise easily accessible.

The graphic presented here shows a sample of the population of TNOs observed with Herschel, arranged to showcase these properties.

What is most striking is their diversity. They range from just below 50 km to almost 2400 km in diameter; Pluto and Eris are the largest.

Two worlds have distinctly elongated shapes: Haumea (seen in white) and Varuna (brown). Some even host their own moons (not shown).

The albedo measurement implies a variety of surface compositions: low albedo (brown) is an indication of dark surface materials, such as organic material, while higher albedo (white) suggests pure ices.

TNOs are thought to be some of the most primitive remnants of the planet-forming era. Thus the results of the Herschel “TNOs are cool: A survey of the trans-Neptunian region” open key time programme are being used to test different models of Solar System formation and evolution.

Elliptical galaxies: Chandra helps explain 'red and dead galaxies'

Credit: X-ray: NASA /Chandra CXC /Stanford Univ /N.Werner et al.

NASA's Chandra X-ray Observatory has shed new light on the mystery of why giant elliptical galaxies have few, if any, young stars.

This new evidence highlights the important role that supermassive black holes play in the evolution of their host galaxies.

Because star-forming activity in many giant elliptical galaxies has shut down to very low levels, these galaxies mostly house long-lived stars with low masses and red optical colours.

Astronomers have therefore called these galaxies "red and dead."

Previously it was thought that these red and dead galaxies do not contain large amounts of cold gas—the fuel for star formation, helping to explain the lack of young stars.

ESA's Herschel Space Observatory

However, astronomers have used ESA's Herschel Space Observatory to find surprisingly large amounts of cold gas in some giant elliptical galaxies.

In a sample of eight galaxies, six contain large reservoirs of cold gas.

This is the first time that astronomers have seen large quantities of cold gas in giant elliptical galaxies that are not located at the center of a massive galaxy cluster.

With lots of cold gas, astronomers would expect many stars to be forming in these galaxies, contrary to what is observed.

To try to understand this inconsistency, astronomers studied the galaxies at other wavelengths, including X-rays and radio waves.

The Chandra observations map the temperature and density of hot gas in these galaxies.

For the six galaxies containing abundant cold gas, including NGC 4636 and NGC 5044 shown here, the X-ray data provide evidence that the hot gas is cooling, providing a source for the cold gas observed with Herschel.

However, the cooling process stops before the cold gas condenses to form stars. What prevents the stars from forming?

A strong clue comes from the Chandra images. The hot gas in the center of the six galaxies containing cold gas appears to be much more disturbed than in the cold gas-free systems.

This is a sign that material has been ejected from regions close to the central black hole. These outbursts are possibly driven, in part, by clumpy, cold gas that has been pulled onto the black hole.

The outbursts dump most of their energy into the center of the galaxy, where the cold gas is located, preventing the cold gas from cooling sufficiently to form stars.

The other galaxies in the sample, NGC 1399 and NGC 4472, are also forming few if any stars, but they have a very different appearance. No cold gas was detected in these galaxies, and the hot gas in their central regions is much smoother.

Additionally, they have powerful jets of highly energetic particles, as shown in radio images from the National Science Foundation's Karl G. Jansky Very Large Array.

These jets are likely driven by hot gas falling towards the central supermassive black holes.

By pushing against the hot gas, the jets create enormous cavities that are observed in the Chandra images, and they may heat the hot, X-ray emitting gas, preventing it from cooling and forming cold gas and stars.

The centers of NGC 1399 and NGC 4472 look smoother in X-rays than the other galaxies, likely because their more powerful jets produce cavities further away from the center, where the X-ray emission is fainter, leaving their bright cores undisturbed.

More information: A paper describing these results was published on 24 February 2014 in Monthly Notices of the Royal Astronomical Society: mnras.oxfordjournals.org/content/439/3/2291 , Preprint: arxiv.org/abs/1310.5450

ESA Herschel Observatory: Researchers discover young galaxies not behaving as predicted

The young galaxy SDSS090122.37+181432.3. It is distorted because of gravitational lensing. 

Credit: NASA/STScI; S. Allam and team; and the Master Lens Database (masterlens.org), L. A. Moustakas, K. Stewart, et al (2014).

New Herschel Space Observatory findings have given scientists a remarkable insight into the internal dynamics of two young galaxies.

Surprisingly, they have shown that just a few billion years after the big bang, some galaxies were rotating in a mature way, seemingly having completed the accumulation of their gas reservoirs.

When galaxies form, they accumulate mass by gravitationally attracting vast, external gas clouds. As the gas clouds are consumed by the galaxy, they fall into haphazard orbits.

These disordered paths cause turbulence in the host galaxies, which can drive star formation.

James Rhoads

To investigate the internal conditions of forming galaxies, James Rhoads and Sangeeta Malhotra, both from Arizona State University, and colleagues targeted two young galaxies, known as SDSS0901 and the Clone.

The light from both galaxies has taken 10 billion years to reach us across space. Thus, we are seeing them when they were comparatively young.

Rhoads studies galaxy formation, galaxy evolution and the reionization of intergalactic hydrogen by early galaxies.

Malhotra's research ranges from properties of dust and gas in the (relatively nearby) interstellar medium to some of the farthest known galaxies.

Sangeeta Malhotra

In recent years they have also collaborated on finding and characterizing galaxies in the cosmic dawn, when the universe was less than a billion years old.

The current project focuses on a somewhat later time, the high noon of star formation in the universe – a time when the universe was about 3 billion years old, and when star birth in galaxies was much more active than it is today.

"The purpose of this project is to study the physical conditions of gas in those galaxies. We wanted to know: 'Are they similar to the galaxies around us, or is there some difference in their physical conditions?'" says Rhoads.

The two galaxies they choose to study are average galaxies for that time in cosmic history. This means that they are about 10 to 20 percent the size of our Milky Way, which is considered an average galaxy in the present-day universe.

Studying galaxies so far away is usually challenging because they appear too dim to study effectively, but in this case, the researchers were helped by a cosmic mirage known as a gravitational lens.

The two galaxies both sit behind intervening groups of galaxies, whose gravity warps space.

As described by Albert Einstein's General Theory of Relativity, this warping acts like a lens.

Although it distorts the images of the young galaxies, it helps by magnifying their light, thus bringing them within reach of ESA Herschel's HIFI instrument.

Read the full article here

Water Found on Dwarf Planet Ceres, May Erupt from Ice Volcanoes

An artist's impression of water outgassing from two sources on the dwarf planet Ceres, which is also the largest asteroid in the solar system. 

Credit: IMCCE-Observatoire de Paris/CNRS/Y.Gominet, B. Carry

Astronomers have discovered direct evidence of water on the dwarf planet Ceres in the form of vapour plumes erupting into space, possibly from volcano-like ice geysers on its surface.

Using European Space Agency's Herschel Space Observatory, scientists detected water vapor escaping from two regions on Ceres, a dwarf planet that is also the largest asteroid in the solar system.

The water is likely erupting from icy volcanoes or sublimation of ice into clouds of vapour.

Artist's impression of Ceres. Credit: ESA/ATG medialab

"This is the first clear-cut detection of water on Ceres and in the asteroid belt in general," said Michael Küppers of the European Space Agency, Villanueva de la Cañada, Spain, leader of the study detailed today (Jan. 22) in the journal Nature.

The research has implications for how Ceres formed, and supports models that suggest the planets moved around a lot within the solar system during its formation, Küppers told reporters.

ESA Scientists have suspected that there is a substantial amount of water on Ceres for about 30 years.

An earlier study found hints of water in the form of hydroxide, a product of water's dissociation, on Ceres in 1991, but the finding wasn't confirmed by later observations.

Now, Küppers and his ESA colleagues have confirmed the finding, using the ESA Herschel Space Observatory's spectrometer to look for signals of water.

Clouds of water vapour around Ceres absorbed the heat that radiates from the dwarf planet, which Herschel's instrument detected.

The team found that Ceres produces about 2×10^26 molecules, or 13 lbs. (6 kilograms), of water vapour per second from its surface.

Read the full article on the ESA Herschel portal

More Information: 'Localized sources of water vapour on the dwarf planet Ceres': Nature 505, 525–527 (23 January 2014) doi:10.1038/nature12918

Obese Black-Hole Galaxies Could Reveal Quasar Secrets

Obese black-hole galaxies could be a stepping stone to the quasars we see today. 

CREDIT: NASA/ESA 

Gluttonous black holes in the center of some galaxies could be precursors to the brightest objects in the known universe.

A recently proposed type of galaxy with an overwhelmingly large black hole in its center could give astronomers a better understanding of the formation of quasars — bright objects in galaxies with supe-rmassive black holes.

The centers of these obese black-hole galaxies (OBGs) could harbour black holes so massive that radiation from where the black hole accretes would overwhelm that of the stars within its galaxy.

New research indicates that some of the most luminous quasars seen from Earth were likely OBGs first before something "lit up" the black hole and had it pump out energy visible from Earth.

The simulations indicate there could be a million OBGs in the observable universe, making the team behind the work ask, why don't we see them?

Tanking up
The team, led by scientists from the Max Planck Institute for Extraterrestrial Physics in Germany, was trying to figure out why astronomers can see quasars from a very far away, at the beginning of the universe. (More distant objects are older and have less metal in them.)

"People have hypothesized there could be these black holes forming from this metal-free gas reservoir ... which is completely free of stars," said Bhaskar Agarwal, a doctoral research fellow at Max Planck who led the research.

This means the black holes in OBGs could have formed separately from the stars surrounding them, contradicting recent observations by the Herschel Space Observatory.

In that earlier finding, astronomers suggested that galaxies that have black holes in their center — including the Milky Way — see the stars and black holes evolve together.

Other research, including observational research, also shows OBG-like objects with a very massive black hole at the center of the galaxy, Agarwal told reporters.

But if the black holes in OBGs formed solo from a reservoir of gas, the stars must have come from somewhere.

The simulations suggested the black hole would have remained on its own until a merger between galaxies brought stars within its vicinity.

The results were published in the Monthly Notices of the Royal Astronomical Society by Oxford University Press on May 29.

Participating researchers came from Max Planck, Yale University and the University of Edinburgh.

ESA's Herschel Space Observatory: Ancient Galaxy Producing Stars at Record Pace

Artist's impression of a starburst galaxy similar to the distant HFLS 3, which was churning out stars at a record-setting pace less than a billion years after the Big Bang.

CREDIT: ESA–C. Carreau

Astronomers peering into the early history of the universe have spotted perhaps the most productive star-forming galaxy ever found.

Known as HFLS 3, the young galaxy churns out about 3,000 new stars each year — more than 2,000 times as many as the Milky Way averages, and up to 20 times more than the number created by similar galaxies today.

The massive starburst galaxy existed only 880 million years after the Big Bang that created our universe 13.8 billion years ago, making HFLS 3 the most distant known pure starburst galaxy.

"One of the big surprises was how evolved this galaxy is in terms of its properties," stated principal investigator Dominik Riechers of Cornell University.

Dominik Riechers

Starburst galaxies exist today, burning through their stores of dust and gas to produce stars at a fantastic rate. But HFLS 3 is 15 to 20 times larger, and produces 15 to 20 times more stars, than similar current galaxies.

The difference is in the dust. Early in the history of the universe, when less dust had been converted to stars, galaxies such as HFLS 3 had access to more raw materials.

"The same processes are involved, but just 'supersized,'" Riechers said.

One of tens of thousands of early starburst galaxies detected by the European Space Agency's (ESA) Herschel Space Observatory, HFLS 3 attracted attention because it appeared very red among the rest, which indicated the possibility of greater distance.

Riechers and a team of international astronomers used a suite of instruments from around the world to study the distant structure.

"Finding this galaxy was like looking for a needle in a haystack," Riechers said.