Releases from NASA, NASA's Galex, NASA's Goddard Space Flight Center, HubbleSite, Spitzer, Cassini, ESO, ESA, Chandra, HiRISE, Royal Astronomical Society, NRAO, Astronomy Picture of the Day, Harvard-Smithsonian Center For Astrophysics, Max Planck Institute for Astrophysics, Gemini Observatory, Subaru Telescope, W. M. Keck Observatory, Fermi Gamma-ray Space Telescope, JPL-Caltech, etc
These three images, created from Cassini
Synthetic Aperture Radar (SAR) data, show the appearance and evolution
of a mysterious feature in Ligeia Mare, one of the largest hydrocarbon
seas on Saturn's moon Titan. Image credit: NASA/JPL-Caltech/ASI/Cornell.Full image and caption - (Images of the feature taken during the Cassini flybys)
NASA's Cassini spacecraft is monitoring the evolution of a mysterious
feature in a large hydrocarbon sea on Saturn's moon Titan. The feature
covers an area of about 100 square miles (260 square kilometers) in
Ligeia Mare, one of the largest seas on Titan. It has now been observed
twice by Cassini's radar experiment, but its appearance changed between
the two apparitions.
The mysterious feature, which appears bright in radar images against
the dark background of the liquid sea, was first spotted during
Cassini's July 2013 Titan flyby. Previous observations showed no sign of
bright features in that part of Ligeia Mare. Scientists were perplexed
to find the feature had vanished when they looked again, over several
months, with low-resolution radar and Cassini's infrared imager. This
led some team members to suggest it might have been a transient feature.
But during Cassini's flyby on August 21, 2014, the feature was again
visible, and its appearance had changed during the 11 months since it
was last seen.
Scientists on the radar team are confident that the feature is not an
artifact, or flaw, in their data, which would have been one of the
simplest explanations. They also do not see evidence that its appearance
results from evaporation in the sea, as the overall shoreline of Ligeia
Mare has not changed noticeably.
The team has suggested the feature could be surface waves, rising
bubbles, floating solids, solids suspended just below the surface, or
perhaps something more exotic.
The researchers suspect that the appearance of this feature could be
related to changing seasons on Titan, as summer draws near in the moon's
northern hemisphere. Monitoring such changes is a major goal for
Cassini's current extended mission.
"Science loves a mystery, and with this enigmatic feature, we have a
thrilling example of ongoing change on Titan," said Stephen Wall, the
deputy team lead of Cassini's radar team, based at NASA's Jet Propulsion
Laboratory in Pasadena, California. "We're hopeful that we'll be able
to continue watching the changes unfold and gain insights about what's
going on in that alien sea."
The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency and ASI, the Italian Space Agency. JPL, a division
of the California Institute of Technology in Pasadena, manages the
mission for NASA's Science Mission Directorate, Washington. The radar
instrument was built by JPL and the Italian Space Agency, working with
team members from the United States and several European countries.
Image at 7 mm wavelength of the
dusty disk around the star HD 169142 obtained with the Very Large Array
(VLA) at 7 mm wavelength. The positions of the protoplanet candidates
are marked with plus signs (+) (Osorio et al. 2014, ApJ, 791, L36). The
insert in the upper right corner shows, at the same scale, the bright
infrared source in the inner disk cavity, as observed with the Very
Large Telescope (VLT) at 3.8 micron wavelength (Reggiani et al. 2014,
ApJ, 792, L23).
Young star HD169142 displays a disk of gas and dust with two annular gaps possibly due to the formation of planets
Planets are formed from disks of gas and dust that orbit around young
stars. Once the “seed” of the planet —composed of a small aggregate of
dust— is formed, it will continue to gather material and it will carve
out a cavity or gap in the disk along its orbital path.
This transitional stage between the original disk and the planetary
system, difficult to study and as yet little known, is precisely what
has been observed in the star HD169142 and is discussed in two articles
published in The Astrophysical Journal Letters.
"Although in recent years more than seventeen hundred extrasolar
planets have been discovered, few of them have been directly imaged, and
so far we have never been able to capture an unequivocal image of an
still-forming planet”, says Mayra Osorio, researcher at the Institute of
Astrophysics of Andalusia (IAA-CSIC) heading one of the articles. “In
HD 169142 we may be seeing indeed those seeds of gas and dust which will
later become planets."
HD169142 is a young star with twice the mass of the Sun and whose disk
extends up to two hundred and fifty astronomical units (an astronomical
unit, or AU, is a unit equivalent to the distance between the Sun and
the Earth: one hundred and fifty million kilometers). The system is in
an optimal orientation for the study of planet formation because the
disk is seen face-on.
The first article explores the disk of HD169142 with the Very Large Array radio
telescope, which can detect centimeter-sized dust grains. The results,
combined with infrared data which trace the presence of microscopic
dust, reveal two gaps in the disk, one in the inner region (between 0.7
and 20 AU) and another, farther out and less developed, between 30 and
"This structure already suggested that the disk was being modified by
two planets or sub-stellar objects, but, additionally, the radio data
reveal the existence of a clump of material within the external gap,
located approximately at the distance of Neptune’s orbit, which points
to the existence of a forming planet”, says Mayra Osorio (IAA-CSIC).
ONE (OR TWO) COMPANIONS AROUND HD169142
The second study focused on searching for infrared sources in the gaps of the disk, using the Very Large Telescope.
They found a bright signal in the inner gap, which could correspond to a
still-forming planet or to a young brown dwarf (a sort of failed star
that never reached the threshold mass to trigger the nuclear reactions
characteristic of stars).
Infrared data did not, however, corroborate the presence of an object
in the outer gap as radio observations suggested. This non detection
could be due to technical limitations: the researchers have calculated
that an object with a mass between one tenth and 18 times the Jupiter’s
mass surrounded by a cold envelope may well remain undetected at the
"In future observations we will be able to verify whether the disk
harbors one or two objects. In any case, HD 169142 remains as a
promising object since it is one of the few known transitional disks and
it is revealing to us the environment where planets are formed", says
Mayra Osorio (IAA-CSIC).
An artist's impression of a protoplanetary disk
Credit: ESO/L. Calçada
M. Osorio et al. "Imaging the Inner and Outer Gaps of the Pre-Transitional Disk of HD 169142 at 7 mm". The Astrophysical Journal ApJ 791 L36. DOI:10.1088/2041-8205/791/2/L36
M. Reggiani et al. "Discovery of a companion candidate in the HD169142
transition disk and the possibility of multiple planet formation". The Astrophysical Journal. 792, L23, DOI: 10.1088/2041-8205/792/1/L23
Instituto de Astrofísica de Andalucía (IAA-CSIC)
Unidad de Divulgación y Comunicación
Silbia López de Lacalle - Email:email@example.com - 958230532
Detection of iso-propyl cyanide with ALMA, the Atacama Large Millimeter/submillimeter Array
Scientists from the Max Planck Institute for Radio Astronomy
(Bonn, Germany), Cornell University (USA), and the University of Cologne
(Germany) have for the first time detected a carbon-bearing molecule
with a "branched" structure in interstellar space. The molecule, iso-propyl cyanide (i-C3H7CN),
was discovered in a giant gas cloud called Sagittarius B2, a region of
ongoing star formation close to the center of our galaxy that is a
hot-spot for molecule-hunting astronomers. The branched structure of the
carbon atoms within the iso-propyl cyanide molecule is unlike
the straight-chain carbon backbone of other molecules that have been
detected so far, including its sister molecule normal-propyl cyanide. The discovery of iso-propyl
cyanide opens a new frontier in the complexity of molecules found in
regions of star formation, and bodes well for the presence of amino
acids, for which this branched structure is a key characteristic. The results are published in this week’s issue of “Science”.
While various types of molecules have been detected in space, the
kind of hydrogen-rich, carbon-bearing (organic) molecules that are most
closely related to the ones necessary for life on Earth appear to be
most plentiful in the gas clouds from which new stars are being formed.
"Understanding the production of organic material at the early stages of
star formation is critical to piecing together the gradual progression
from simple molecules to potentially life-bearing chemistry," says
Arnaud Belloche from the Max Planck Institute for Radio Astronomy, the
lead author of the paper.
The search for molecules in interstellar space began in the 1960's,
and around 180 different molecular species have been discovered so far.
Each type of molecule emits light at particular wavelengths, in its own
characteristic pattern, or spectrum, acting like a fingerprint that
allows it to be detected in space using radio telescopes.
Until now, the organic molecules discovered in star-forming regions
have shared one major structural characteristic: they each consist of a
"backbone" of carbon atoms that are arranged in a single and more or
less straight chain. The new molecule discovered by the team, iso-propyl
cyanide, is unique in that its underlying carbon structure branches off
in a separate strand. "This is the first ever interstellar detection of
a molecule with a branched carbon backbone," says Holger Müller, a
spectroscopist at the University of Cologne and co-author on the paper,
who measured the spectral fingerprint of the molecule in the laboratory,
allowing it to be detected in space.
But it is not just the structure of the molecule that surprised the
team - it is also plentiful, at almost half the abundance of its
straight-chain sister molecule, normal-propyl cyanide (n-C3H7CN),
which the team had already detected using the single-dish radio
telescope of the Institut de Radioastronomie Millimétrique (IRAM) a few
years ago. "The enormous abundance of iso-propyl cyanide suggests
that branched molecules may in fact be the rule, rather than the
exception, in the interstellar medium," says Robin Garrod, an
astrochemist at Cornell University and a co-author of the paper.
The team used the Atacama Large Millimeter/submillimeter Array
(ALMA), in Chile, to probe the molecular content of the star-forming
region Sagittarius B2 (Sgr B2). This region is located close to the
Galactic Center, at a distance of about 27,000 light years from the Sun,
and is uniquely rich in emission from complex interstellar organic
molecules. "Thanks to the new capabilities offered by ALMA, we were able
to perform a full spectral survey toward Sgr B2 at wavelengths between
2.7 and 3.6 mm, with sensitivity and spatial resolution ten times
greater than our previous survey," explains Belloche. "But this took
only a tenth of the time." The team used this spectral survey to search
systematically for the fingerprints of new interstellar molecules. "By
employing predictions from the Cologne Database for Molecular
Spectroscopy, we could identify emission features from both varieties of
propyl cyanide," says Müller. As many as 50 individual features for i-propyl cyanide and even 120 for n-propyl
cyanide were unambiguously identified in the ALMA spectrum of Sgr B2.
The two molecules, each consisting of 12 atoms, are also the
joint-largest molecules yet detected in any star-forming region.
The team constructed computational models that simulate the chemistry
of formation of the molecules detected in Sgr B2. In common with many
other complex organics, both forms of propyl cyanide were found to be
efficiently formed on the surfaces of interstellar dust grains. "But,"
says Garrod, "the models indicate that for molecules large enough to
produce branched side-chain structure, these may be the prevalent forms.
The detection of the next member of the alkyl cyanide series, n-butyl cyanide (n-C4H9CN), and its three branched isomers would allow us to test this idea".
"Amino acids identified in meteorites have a composition that
suggests they originate in the interstellar medium," adds Belloche.
“Although no interstellar amino acids have yet been found, interstellar
chemistry may be responsible for the production of a wide range of
important complex molecules that eventually find their way to planetary
"The detection of iso-propyl cyanide tells us that amino acids
could indeed be present in the interstellar medium because the
side-chain structure is a key characteristic of these molecules", says
Karl Menten, director at MPIfR and head of its Millimeter and
Submillimeter Astronomy research department. "Amino acids have already
been identified in meteorites and we hope to detect them in the
interstellar medium in the future", he concludes.
Astronomers have analyzed the orbits of 365 observed systems of suspected, multiple exoplanets. This figure shows the relative placements and sizes of the planets in systems with three or more planets. The horizontal axis shows the orbital period in days for these systems, in all of which the planets are very to their stars and so complete their annual orbit in under about 100 days (a few suspected planets orbit in under one day!). The planetary radii are colored with the largest in each system being red; most of the planets in this study are between about one and four Earth-radii.
are 1822 confirmed exoplanets reported so far, and NASA's Kepler
satellite has found evidence for more than two thousand others. Many
exoplanets are expected to be in systems with multiple planets; indeed,
one Kepler system is thought to contain seven or perhaps even more
planets. As astronomers amass data on the characteristics of planets of
all kinds, the large number of expected planetary systems allows them
to study as well the nature of these systems and the stability of the
orbits over time.
CfA astronomers Darin Ragozzine, John Geary, and Matt Holman,
together with their colleagues, have analyzed 899 transiting planet
candidates in 365 systems in an effort to understand the statistical
properties of planetary systems and the extent to which our solar system
might be unusual. The most complex system in their set has six
planets. The sample is dominated by planets between about one and four
Earth-radii in size and which orbit their stars in about ten days,
making the planets hot and not Earth-like.
The astronomers found one striking feature of these exoplanetary
systems: the planets seemed to lie in the same plane, to within an
estimated 2.5 degrees (the team also estimates how this value might vary
in time). For comparison, the solar system's planets are coplanar to
about 3 degrees, with Mercury being an outlier with its angle of seven
degrees; Pluto (not a planet) has an orbital angle of seventeen degrees.
The team argues that this exoplanet result suggests that the
individual planetary orbits are each nearly circular, a significant
conclusion because it means the orbits are not likely to overlap, and
hence implies (at least for systems of close-in planets) that they have
long-term stability. The new paper marks continuing significant
progress in unraveling the picture of planets and planetary systems in
of Kepler's Multi-Transiting Systems. II. New Investigations with Twice
as Many Candidates," Daniel C. Fabrycky, Jack J. Lissauer, Darin
Ragozzine, Jason F. Rowe, Jason H. Steffen, Eric Agol, Thomas Barclay,
Natalie Batalha, William Borucki, David R. Ciardi, Eric B. Ford, Thomas
N. Gautier, John C. Geary, Matthew J. Holman, Jon M. Jenkins, Jie Li,
Robert C. Morehead, Robert L. Morris, Avi Shporer, Jeffrey C. Smith,
Martin Still, and Jeffrey Van Cleve, ApJ 790, 146, 2014
An illustration of water in our Solar
System through time from before the Sun’s birth through the creation of
the planets. The image is credited to Bill Saxton, NSF/AUI/NRAO. A
larger version is availablehere. Another image is availablehere.
Washington, D.C.—Water was crucial to the rise of
life on Earth and is also important to evaluating the possibility of
life on other planets. Identifying the original source of Earth’s water
is key to understanding how life-fostering environments come into being
and how likely they are to be found elsewhere. New work from a team
including Carnegie’s Conel Alexander found that much of our Solar
System’s water likely originated as ices that formed in interstellar
space. Their work is published in Science.
Water is found throughout our Solar System. Not just on Earth, but on
icy comets and moons, and in the shadowed basins of Mercury. Water has
been found included in mineral samples from meteorites, the Moon, and
Comets and asteroids in particular, being primitive objects, provide a
natural “time capsule” of the conditions during the early days of our
Solar System. Their ices can tell scientists about the ice that
encircled the Sun after its birth, the origin of which was an unanswered
question until now.
In its youth, the Sun was surrounded by a protoplanetary disk, the
so-called solar nebula, from which the planets were born. But it was
unclear to researchers whether the ice in this disk originated from the
Sun’s own parental interstellar molecular cloud, from which it was
created, or whether this interstellar water had been destroyed and was
re-formed by the chemical reactions taking place in the solar nebula.
“Why this is important? If water in the early Solar System was
primarily inherited as ice from interstellar space, then it is likely
that similar ices, along with the prebiotic organic matter that they
contain, are abundant in most or all protoplanetary disks around forming
stars,” Alexander explained. “But if the early Solar System’s water was
largely the result of local chemical processing during the Sun’s birth,
then it is possible that the abundance of water varies considerably in
forming planetary systems, which would obviously have implications for
the potential for the emergence of life elsewhere.”
In studying the history of our Solar System’s ices, the team—led by
L. Ilsedore Cleeves from the University of Michigan—focused on hydrogen
and its heavier isotope deuterium. Isotopes are atoms of the same
element that have the same number of protons but a different number of
neutrons. The difference in masses between isotopes results in subtle
differences in their behavior during chemical reactions. As a result,
the ratio of hydrogen to deuterium in water molecules can tell
scientists about the conditions under which the molecules formed.
For example, interstellar water-ice has a high ratio of deuterium to
hydrogen because of the very low temperatures at which it forms. Until
now, it was unknown how much of this deuterium enrichment was removed by
chemical processing during the Sun’s birth, or how much deuterium-rich
water-ice the newborn Solar System was capable of producing on its own.
So the team created models that simulated a protoplanetary disk in
which all the deuterium from space ice has already been eliminated by
chemical processing, and the system has to start over “from scratch” at
producing ice with deuterium in it during a million-year period. They
did this in order to see if the system can reach the ratios of deuterium
to hydrogen that are found in meteorite samples, Earth’s ocean water,
and “time capsule” comets. They found that it could not do so, which
told them that at least some of the water in our own Solar System has an
origin in interstellar space and pre-dates the birth of the Sun.
“Our findings show that a significant fraction of our Solar System’s
water, the most-fundamental ingredient to fostering life, is older than
the Sun, which indicates that abundant, organic-rich interstellar ices
should probably be found in all young planetary systems,” Alexander
* * * * * * * *
This research was supported by the NSF, the Rackham Predoctoral Fellowship, NASA Astrobiology, NASA Cosmochemistry and NASA.
Two main types of explosions occur on the sun: solar flares and coronal mass ejections. Unlike the energy and x-rays produced in a solar flare – which can reach Earth at the speed of light in eight minutes – coronal mass ejections are giant clouds of solar material that take one to three days to reach Earth. Once at Earth, these ejections, also called CMEs, can impact satellites in space or interfere with radio communications. During CME Week from Sept. 22 to 26, 2014, we explore different aspects of these giant eruptions that surge out from the star we live with.
weather models combined with real time observations help scientists
track CMEs. These images were produced from a model known as ENLIL named
after the Sumerian storm god. It shows the journey of a CME on March 5,
2013, as it moved toward Mars. Image Credit: NASA/Goddard/SWRC/CCMC. Download video
March 5, 2013, CME as seen by the Solar and Heliospheric Observatory.
Combining the information gleaned from such imagery with
state-of-the-art models helps scientists better understand how CMEs move
toward, and affect, Earth. Image Credit: ESA/NASA/SOHO/Jhelioviewer
Those who study Earth's weather have a luxury of data points to study.
From thousands of weather stations measuring temperature and rainfall to
satellites tracking storm fronts up in space, meteorologists can watch
detailed maps of the weather as it sweeps across land or sea.
Compared to this, the study of space weather – including CMEs – is a
much younger science, with far fewer observatories available. However,
our resources have grown dramatically in the last decade: NASA currently
flies 18 missions to study the sun's effects at Earth and on the entire
solar system, a field known as heliophysics, and additionally launches
numerous short-flight rockets for observations of solar impacts in and
above Earth's atmosphere. Coupled with improved computer modeling,
keeping an eye on – and getting a better understanding of – CMEs has
taken a giant leap forward in the 21st century.
"Over the past ten years, we have had a major breakthrough in
understanding space weather," said Antti Pulkkinen a space weather
scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland.
"We can now track the basic properties of CMEs. When our solar
observatories see a CME, we can tell what direction it's going in and
how fast it's traveling."
Improved observations combined with improved models has led to hybrid
descriptions of a CME, relying partially on computer simulations and
partially on actual observations. NASA houses a collection of space
weather models available for public access at the Community Coordinated
Modeling Center at Goddard. Together with observations they can provide a
holistic picture of any given CME.
For example, NASA's Solar and Terrestrial Relations Observatory, or STEREO, might see a CME erupt on the sun. When that imagery is combined with observations from the European Space Agency and NASA's Solar and Heliospheric Observatory, or SOHO, scientists can create a 3-dimensional picture of the giant cloud. Scientists then input this data into a model and then track how the CME unfolded and spread through space until it passed by NASA observatories closer to Earth. These observatories can directly measure the magnetic fields and speed of the CME as it passes by, as well as see how it affected Earth's own magnetic fields – the magnetosphere.
By gathering data from numerous observatories, scientists can create
models and explore what-if scenarios about what would happen near Earth
due to a given CME. Watch the video to learn more about what scientists
can see in these models. Image Credit: NASA/Bridgman/Duberstein.Download video
information on the CME's entire path opens the door to understanding
why any given characteristic of the CME near the sun might lead to a
given effect near Earth. Each additional piece of the puzzle helps us
better understand just what causes these giant eruptions -- and whether
or not any particular CME could pose a hazard to astronauts as well as
technology in space and on the ground.
Acknowledgement: D. Calzetti (University of Massachusetts) and the LEGUS Team
This new image from the NASA/ESA Hubble Space Telescope shows NGC
7793, a spiral galaxy in the constellation of Sculptor some 13 million
light-years away from Earth. NGC 7793 is one of the brightest galaxies
in the Sculptor Group, and one of the closest groups of galaxies to the Local Group — the group of galaxies containing our galaxy, the Milky Way and the Magellanic Clouds.
The image shows NGC 7793’s spiral arms and small central bulge.
Unlike some other spirals, NGC 7793 doesn’t have a very pronounced
spiral structure, and its shape is further muddled by the mottled
pattern of dark dust that stretches across the frame. The occasional
burst of bright pink can be seen in the galaxy, highlighting stellar
nurseries containing newly-forming baby stars.
Although it may look serene and beautiful from our perspective, this
galaxy is actually a very dramatic and violent place. Astronomers have
discovered a powerful microquasar within NGC 7793 — a system containing a
black hole actively feeding on material from a companion star. While
many full-sized quasars are known at the cores of other galaxies, it is
unusual to find a quasar in a galaxy’s disc rather than at its centre.
Micro-quasars are almost like scale models — they allow astronomers
to study quasars in detail. As material falls inwards towards this black
hole, it creates a swirling disc around it. Some of the infalling gas
is propelled violently outwards at extremely high speeds, creating jets
streaking out into space in opposite directions. In the case of NGC
7793, these jets are incredibly powerful, and are in the process of
creating an expanding bubble of hot gas some 1000 light-years across.
Hubble snaps what looks like a young galaxy in the local Universe
Astronomers usually have to peer very far
into the distance to see back in time, and view the Universe as it was
when it was young. This new NASA/ESA Hubble Space Telescope image of
galaxy DDO 68, otherwise known as UGC 5340, was thought to offer an
exception. This ragged collection of stars and gas clouds looks at first
glance like a recently-formed galaxy in our own cosmic neighbourhood.
But, is it really as young as it looks?
Astronomers have studied galactic evolution for decades, gradually
improving our knowledge of how galaxies have changed over cosmic
history. The NASA/ESA Hubble Space Telescope has played a big part in
this, allowing astronomers to see further into the distance, and hence
further back in time, than any telescope before it — capturing light
that has taken billions of years to reach us.
Looking further into the very distant past to observe younger and
younger galaxies is very valuable, but it is not without its
problems for astronomers. All newly-born galaxies lie very far away from
us and appear very small and faint in the images. On the contrary, all
the galaxies near to us appear to be old ones.
DDO 68, captured here by the NASA/ESA Hubble Space Telescope, was one
of the best candidates so far discovered for a newly-formed galaxy in
our cosmic neighbourhood. The galaxy lies around 39 million light-years
away from us; although this distance may seem huge, it is in fact
roughly 50 times closer than the usual distances to such galaxies, which
are on the order of several billions of light years.
By studying galaxies of various ages, astronomers have found that
those early in their lives are fundamentally different from those that
are older. DDO 68 looks to be relatively youthful based on its
structure, appearance, and composition. However, without more detailed
modelling astronomers cannot be sure and they think it may be older than
it lets on.
Elderly galaxies tend to be larger thanks to collisions and mergers
with other galaxies that have bulked them out, and are populated with a
variety of different types of stars — including old, young, large, and
small ones. Their chemical makeup is different too. Newly-formed
galaxies have a similar composition to the primordial matter created in
the Big Bang (hydrogen, helium and a little lithium), while older
galaxies are enriched with heavier elements forged in stellar furnaces
over multiple generations of stars.
DDO 68 is the best representation yet of a primordial galaxy in the
local Universe as it appears at first glance to be very low in heavier
elements — whose presence would be a sign of the existence of previous
generations of stars.
Hubble observations were carried out in order to study the properties
of the galaxy’s light, and to confirm whether or not there are any
older stars in DDO 68. If there are, which there seem to be, this would
disprove the hypothesis that it is entirely made up of young stars. If
not, it would confirm the unique nature of this galaxy. More complex
modelling is needed before we can know for sure but Hubble's picture
certainly gives us a beautiful view of this unusual object.
The image is made up of exposures in visible and infrared light taken with Hubble's Advanced Camera for Surveys.
The Hubble Space Telescope is a project of international cooperation between ESA and NASA.
Image credit:NASA&ESA Acknowledgement: A. Aloisi (Space Telescope Science Institute)
Two main types of explosions occur on the sun: solar flares and
coronal mass ejections. Unlike the energy and X-rays produced in a solar
flare – which can reach Earth at the speed of light in eight minutes –
coronal mass ejections are giant clouds of solar material that take one
to three days to reach Earth. Once at Earth, these ejections, also
called CMEs, can impact satellites in space or interfere with radio
communications. During CME Week from Sept. 22 to 26, 2014, we explore
different aspects of these giant eruptions that surge out from our
NASA observatories work together to help scientists track the journey
of a massive coronal mass ejection, or CME, in July 2012. Image Credit: NASA/SDO/STEREO/ESA/SOHO/Wiessinger.Download video
On July 23, 2012, a massive cloud of solar material erupted off the
sun's right side, zooming out into space. It soon passed one of NASA's
Solar Terrestrial Relations Observatory, or STEREO, spacecraft, which
clocked the CME as traveling between 1,800 and 2,200 miles per second as
it left the sun. This was the fastest CME ever observed by STEREO.
other observatories – NASA's Solar Dynamics Observatory and the joint
European Space Agency/NASA Solar and Heliospheric Observatory --
witnessed the eruption as well. The July 2012 CME didn't move toward
Earth, but watching an unusually strong CME like this gives scientists
an opportunity to observe how these events originate and travel through
STEREO's unique viewpoint from the sides of the sun combined with the
other two observatories watching from closer to Earth.Together they
helped scientists create models of the entire July 2012 event. They
learned that an earlier, smaller CME helped clear the path for the
larger event, thus contributing to its unusual speed.
Such data helps advance our understanding of what causes CMEs and
improves modeling of similar CMEs that could be Earth-directed.
Watch the movie to see how NASA's solar-observing missions worked together to track this CME.
Artist's Illustration of Clear Skies on Exoplanet HAT-P-11b
Scientists were excited to discover clear skies on a relatively small
planet, about the size of Neptune, using the combined power of NASA's
Hubble, Spitzer, and Kepler space telescopes. The view from this planet
— were it possible to fly a spaceship into its gaseous layers — is
illustrated at right. Before now, all of the planets observed in this
size range had been found to have high cloud layers that blocked the
ability to detect molecules in the planet's atmosphere (illustrated at
The clear planet, called HAT-P-11b, is gaseous with a rocky core,
much like our own Neptune. Its atmosphere may have clouds deeper down,
but the new observations show that the upper region is cloud-free. This
good visibility enabled scientists to detect water vapor molecules in
the planet's atmosphere. Illustration Credit:NASA,ESA, and R. Hurt (JPL-Caltech)
Artist's Illustration of Exoplanet HAT-P-11b
A Neptune-size planet with a clear atmosphere is shown crossing in
front of its star in this artist's depiction. Such crossings, or
transits, are observed by telescopes like NASA's Hubble and Spitzer to
glean information about planets' atmospheres. As starlight passes
through a planet's atmosphere, atoms and molecules absorb light at
certain wavelengths, blocking it from the telescope's view. The more
light a planet blocks, the larger the planet appears. By analyzing the
amount of light blocked by the planet at different wavelengths,
researchers can determine which molecules make up the atmosphere.
The problem with this technique is that sometimes planets have thick
clouds that block any light from coming through, hiding the signature
of the molecules in the atmosphere. This is particularly true of the
handful of Neptune-sized and super-Earth planets examined to date, all
of which appear to be cloudy.
As a result, astronomers were elated to find clear skies on a
Neptune-sized planet called HAT-P-11b, as illustrated here. Without
clouds to block their view, they were able to identify water vapor
molecules in the planet's atmosphere. The blue rim of the planet in
this image is due to scattered light, while the orange rim on the part
of the planet in front of the star indicates the region where water
vapor was detected. Illustration Credit:NASA,ESA, and R. Hurt (JPL-Caltech)
Artist's Illustration of HAT-P-11b Transmission Spectrum Plot
A plot of the transmission spectrum for exoplanet HAT-P-11b, with
Kepler, Hubble WFC3, and Spitzer transits combined. The results show a
robust detection of water absorption in the WFC3 data. Transmission
spectra of selected atmospheric models are plotted for comparison. Credit:NASA,ESA, and A. Feild (STScI)
Astronomers using data from three of NASA's space telescopes —
Hubble, Spitzer, and Kepler — have discovered clear skies and steamy
water vapor on a gaseous planet outside our solar system. The planet is
about the size of Neptune, making it the smallest for which molecules
of any kind have been detected.
"This discovery is a significant milepost on the road to eventually
analyzing the atmospheric composition of smaller, rocky planets more
like Earth," said John Grunsfeld, assistant administrator of NASA's
Science Mission Directorate in Washington. "Such achievements are only
possible today with the combined capabilities of these unique and
Clouds in the atmospheres of planets can block the view to underlying
molecules that reveal information about the planets' compositions and
histories. Finding clear skies on a Neptune-size planet is a good sign
that smaller planets might have similarly good visibility.
"When astronomers go observing at night with telescopes, they say
'clear skies' to mean good luck," said Jonathan Fraine of the
University of Maryland, College Park, lead author of a new study
appearing in Nature. "In this case, we found clear skies on a distant
planet. That's lucky for us because it means clouds didn't block our
view of water molecules."
The planet, HAT-P-11b, is a so-called exo-Neptune — a Neptune-size
planet that orbits another star. It is located 120 light-years away in
the constellation Cygnus. Unlike our Neptune, this planet orbits closer
to its star, making one lap roughly every five days. It is a warm
world thought to have a rocky core and gaseous atmosphere. Not much else
was known about the composition of the planet, or other exo-Neptunes
like it, until now.
Part of the challenge in analyzing the atmospheres of planets like
this is their size. Larger, Jupiter-like planets are easier to see
because of their impressive girth and relatively puffy atmospheres. In
fact, researchers have already been able to detect water vapor in those
planets. Smaller planets are more difficult to probe, and what's more,
the ones observed to date all appeared to be cloudy.
In the new study, astronomers set out to look at the atmosphere of
HAT-P-11b, not knowing if its weather would call for clouds or not.
They used Hubble's Wide Field Camera 3, and a technique called
transmission spectroscopy, in which a planet is observed as it crosses
in front of its parent star. Starlight filters through the rim of the
planet's atmosphere and into a telescope's lens. If molecules like water
vapor are present, they absorb some of the starlight, leaving distinct
signatures in the light that reaches our telescopes.
Using this strategy, Hubble was able to detect water vapor in
HAT-P-11b. This technique indicates the planet did not have clouds
blocking the view, a hopeful sign that more cloudless planets can be
located and analyzed in the future.
But before the team could celebrate clear skies on the exo-Neptune,
they had to show that starspots — cooler "freckles" on the face of
stars — were not the real sources of water vapor. Cool starspots on the
parent star can contain water vapor that might appear erroneously to
be from the planet. That's when the team turned to Kepler and Spitzer.
Kepler had been observing one patch of sky for years, and HAT-P-11b
happens to lie in the field. Those visible-light data were combined
with targeted Spitzer observations taken at infrared wavelengths. By
comparing these observations, the astronomers figured out that the
starspots were too hot to have any steam.
It was at that point the team could celebrate detecting water vapor
on a world unlike any in our solar system. "We think that exo-Neptunes
may have diverse compositions, which reflect their formation
histories," said Heather Knutson of the California Institute of
Technology, Pasadena, co-author of the study. "Now with data like these,
we can begin to piece together a narrative for the origin of these
The results from all three telescopes demonstrate that HAT-P-11b is
blanketed in water vapor, hydrogen gas, and likely other
yet-to-be-identified molecules. Theorists will be drawing up new models
to explain the planet's makeup and origins.
"We are working our way down the line, from hot Jupiters to
exo-Neptunes," said Drake Deming, a co-author of the study also from
University of Maryland, College Park. "We want to expand our knowledge
to a diverse range of exoplanets."
The astronomers plan to examine more exo-Neptunes in the future, and
hope to apply the same method to smaller super-Earths — the massive,
rocky cousins to our home world with up to 10 times the mass. Our solar
system doesn't have a super-Earth, but NASA's Kepler mission is
finding them around other stars in droves. NASA's James Webb Space
Telescope, scheduled to launch in 2018, will search super-Earths for
signs of water vapor and other molecules; however, finding signs of
oceans and potentially habitable worlds is likely a ways off.
"The work we are doing now is important for future studies of
super-Earths and even smaller planets, because we want to be able to
pick out in advance the planets with clear atmospheres that will let us
detect molecules," said Knutson.
Once again, astronomers will be crossing their fingers for clear skies.
These images show the distribution of density in the central plane of a
three-dimensional model of a molecular cloud core from which stars are
born. The model computes the cloud’s evolution over the free-fall
timescale, which is how long it would take an object to collapse under
its own gravity without any opposing forces interfering. The free-fall
time is a common metric for measuring the timescale of astrophysical
processes. In a) the free-fall time is 0.0, meaning this is the initial
configuration of the cloud, and moving on the model shows the cloud core
in various stages of collapse: b) a free-fall time of 1.40 or 66,080
years; c) a free-fall time of 1.51 or 71,272 years; and d) a free-fall
time of 1.68 or 79,296 years. Collapse takes somewhat longer than a
free-fall time in this model because of the presence of magnetic fields,
which slow the collapse process, but are not strong enough to prevent
the cloud from fragmenting into a multiple protostar system (d). For
context, the region shown in a) and b) is about 0.21 light years (or 2.0
x 1017 centimeters) across, while the region shown in c) and d) is
about 0.02 light years (or 2.0 x 1016 cm) across. Image is provided
courtesy of Alan Boss.
Washington, D.C.—New modeling studies from
Carnegie’s Alan Boss demonstrate that most of the stars we see were
formed when unstable clusters of newly formed protostars broke up. These
protostars are born out of rotating clouds of dust and gas, which act
as nurseries for star formation. Rare clusters of multiple protostars
remain stable and mature into multi-star systems. The unstable ones will
eject stars until they achieve stability and end up as single or binary
stars. The work is published in The Astrophysical Journal.
About two-thirds of all stars within 81 light years (25 parsecs) of
Earth are binary or part of multi-star systems. Younger star and
protostar populations have a higher frequency of multi-star systems than
older ones, an observation that ties in with Boss’ findings that many
single-star systems start out as binary or multi-star systems from which
stars are ejected to achieve stability.
Protostar clusters are formed when the core of a molecular cloud
collapses due to its own gravity and breaks up into pieces, a process
called fragmentation. The physical forces involved in the collapse are
subjects of great interest to scientists, because they can teach us
about the life cycles of stars and how our own Sun may have been born.
One force that affects collapse is the magnetic field that threads the
clouds, potentially stifling the fragmentation process.
Boss’ work shows that when a cloud collapses, the fragmentation
process depends on the initial strength of the magnetic field, which
acts against the gravity that causes the collapse. Above a certain
magnetic field strength, single protostars are formed, while below it,
the cloud fragments into multiple protostars. This second scenario is
evidently commonplace, given the large number of binary and multi-star
systems, although single stars can form by this mechanism as well
through ejection from a cluster.
“When we look up at the night sky,” Boss said, “the human eye is
unable to see that binary stars are the rule, rather than the exception.
These new calculations help to explain why binaries are so abundant.”
* * *
This work was partially supported by the NSF. The calculations were
performed on the Carnegie Xenia Cluster, the purchase of which was also
partially supported by the NSF.
Artist’s rendition ofAS 205 N, a T Tauri star that is part of a multiple star system.
Image Credit: P. Marenfeld & NOAO/AURA/NSF
Astronomers using the Atacama Large Millimeter/submillimeter Array
(ALMA) have observed what may be the first-ever signs of windy weather
around a T Tauri star, an infant analog of our own Sun. This may help
explain why some T Tauri stars have disks that glow weirdly in infrared
light while others shine in a more expected fashion.
T Tauri stars are the infant versions of stars like our Sun. They are
relatively normal, medium-size stars that are surrounded by the raw
materials to build both rocky and gaseous planets. Though nearly
invisible in optical light, these disks shine in both infrared and
“The material in the disk of a T Tauri star
usually, but not always, emits infrared radiation with a predictable
energy distribution,” said Colette Salyk, an astronomer with the
National Optical Astronomical Observatory (NOAO) in Tucson, Ariz., and
lead author on a paper published in the Astrophysical Journal. “Some T
Tauri stars, however, like to act up by emitting infrared radiation in
To account for the different infrared signature around such similar
stars, astronomers propose that winds may be emanating from within some T
Tauri stars’ protoplanetary disks. These winds could have important
implications for planet formation, potentially robbing the disk of some
of the gas required for the formation of giant Jupiter-like planets, or
stirring up the disk and causing the building blocks of planets to
change location entirely. These winds have been predicted by
astronomers, but have never been clearly detected.
Using ALMA, Salyk and her colleagues looked for evidence of a
possible wind in AS 205 N – a T Tauri star located 407 light-years away
at the edge of a star-forming region in the constellation Ophiuchus, the
Snake Bearer. This star seems to exhibit the strange infrared signature
that has intrigued astronomers.
With ALMA’s exceptional resolution and sensitivity, the researchers
were able to study the distribution of carbon monoxide around the star.
Carbon monoxide is an excellent tracer for the molecular gas that makes
up stars and their planet-forming disks. These studies confirmed that
there was indeed gas leaving the disk’s surface, as would be expected if
a wind were present. The properties of the wind, however, did not
exactly match expectations.
This difference between observations and expectations could be due to
the fact that AS 205 N is actually part of a multiple star system –
with a companion, dubbed AS 205 S, that is itself a binary star.
This multiple star arrangement may suggest that the gas is leaving
the disk’s surface because it’s being pulled away by the binary
companion star rather than ejected by a wind.
“We are hoping these new ALMA observations help us
better understand winds, but they have also left us with a new
mystery,” said Salyk. “Are we seeing winds, or interactions with the
The study’s authors are not pessimistic, however. They plan to
continue their research with more ALMA observations, targeting other
unusual T Tauri stars, with and without companions, to see whether they
show these same features.
T Tauri stars are named after their prototype star, discovered in
1852 – the third star in the constellation Taurus whose brightness was
found to vary erratically. At one point, some 4.5 billion years ago, our
Sun was a T Tauri star.
Other authors include Klaus Pontoppidan, Space Telescope Science
Institute; Stuartt Corder, Joint ALMA Observatory; Diego Muñoz, Center
for Space Research, Department of Astronomy, Cornell University; and Ke
Zhang and Geoffrey Blake, Division of Geological & Planetary
Sciences, California Institute of Technology,
The National Optical Astronomy Observatory is operated by Association
of Universities for Research in Astronomy Inc. under a cooperative
agreement with the National Science Foundation.
The National Radio Astronomy Observatory is a facility of the
National Science Foundation, operated under cooperative agreement by
Associated Universities, Inc. NRAO, together with its international
partners, operates ALMA – the world’s most powerful observatory
operating at millimeter and submillimeter wavelengths.
ALMA, an international astronomy facility, is a partnership of
Europe, North America and East Asia in cooperation with the Republic of
Chile. ALMA construction and operations are led on behalf of Europe by
ESO, on behalf of North America by the National Radio Astronomy
Observatory (NRAO), and on behalf of East Asia by the National
Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory
(JAO) provides the unified leadership and management of the
construction, commissioning and operation of ALMA.
Dr. Katy Garmany
Deputy Press Officer
National Optical Astronomy Observatory
950 N Cherry Ave
Tucson AZ 85719 USA
Dr. Colette Salyk
National Optical Astronomy Observatory
950 N Cherry Ave
Tucson AZ 85719 USA
NRAO Media Contact
Public Information Officer
National Radio Astronomy Observatory
520 Edgemont Road
Charlottesville, VA 22904
The giant planet Saturn is mostly a gigantic ball of rotating gas,
completely unlike our solid home planet. But Earth and Saturn do have
something in common: weather, although the gas giant is home to some of
the most bizarre weather in our Solar System, such as the swirling storm
shown in this Cassini view.
Known as “the hexagon”, this weather
feature is an intense, six-sided jet stream at Saturn’s north pole.
Spanning some 30 000 km across, it hosts howling 320 km/h winds that
spiral around a massive storm rotating anticlockwise at the heart of the
Numerous small vortices rotate in the opposite direction
to the central storm and are dragged around with the jet stream,
creating a terrifically turbulent region. While a hurricane on Earth may
last a week or more, the hexagon has been raging for decades, and shows
no signs of letting up.
This false-colour image of the hexagon was made using ultraviolet, visible and infrared filters to highlight different regions.
dark centre of the image shows the large central storm and its eye,
which is up to 50 times bigger than a terrestrial hurricane eye. The
small vortices show up as pink-red clumps. Towards the lower right of
the frame is a white-tinted oval storm that is bigger than any of the
others — this is the largest of the vortices at some 3500 km across,
twice the size of the largest hurricane ever recorded on Earth.
darker blue region within the hexagon is filled with small haze
particles, whereas the paler blue region is dominated by larger
particles. This divide is caused by the hexagonal jet stream acting as a
shepherding barrier — large particles cannot enter the hexagon from the
These large particles are created when sunlight shines
onto Saturn’s atmosphere, something that only started relatively
recently in the northern hemisphere with the beginning of northern
spring in August 2009.
Cassini will continue to track changes in
the hexagon, monitoring its contents, shape and behaviour as summer
reaches Saturn’s northern hemisphere in 2017.
The Cassini–Huygens mission is a cooperative project of NASA, ESA and Italy's ASI space agency.
In about five billion years time, nearby massive galaxy Andromeda will merge with our own galaxy, the Milky Way, in an act of gallactic cannibalism (technically Andromeda will be eating us, as it's the bigger of the two galaxies.). There haven't been any large mergers with our galaxy recently, but we can see the remnants of galaxies that have previously been snacked on by the Milky Way. We're also going to eat two nearby dwarf galaxies, the Large and Small Magellanic Clouds sometime in the future.
This simulation shows what will happen when the Milky Way and Andromeda get closer together and then collide, and then finally come together once more to merge into an even bigger galaxy.
Simulation Credit: Prof Chris power (ICRAR-UWA), Dr Alex Hobbs (ETH Zurich), Prof Justin Reid (University of Surrey), Dr Dave Cole (University of Central Lancashire) and the Theoretical Astrophysics Group at the University of Leicester.Video Production Credit: Pete Wheeler, ICRAR.
Dr Aaron Robotham
Credit: Joe Liske
Massive galaxies in the Universe have stopped making their own stars
and are instead snacking on nearby galaxies, according to research by
Astronomers looked at more than 22,000 galaxies and found that while
smaller galaxies were very efficient at creating stars from gas, the
most massive galaxies were much less efficient at star formation,
producing hardly any new stars themselves, and instead grew by eating
The study was released today in the journal Monthly Notices of the
Royal Astronomical Society, published by Oxford University Press.
Dr Aaron Robotham based at The University of Western Australia node
of the International Centre for Radio Astronomy Research (ICRAR), said
smaller ‘dwarf’ galaxies were being eaten by their larger counterparts.
“All galaxies start off small and grow by collecting gas and quite efficiently turning it into stars,” he said.
“Then every now and then they get completely cannibalised by some much larger galaxy.”
Dr Robotham, who led the research, said our own Milky Way was at a
tipping point and expected to now grow mainly by eating smaller
galaxies, rather than by collecting gas.
“The Milky Way hasn’t merged with another large galaxy for a long
time but you can still see remnants of all the old galaxies we’ve
cannibalised,” he said.
“We’re also going to eat two nearby dwarf galaxies, the Large and
Small Magellanic Clouds, in about four billion years.”But Dr Robotham
said the Milky Way would eventually get its comeuppance when it merged
with the nearby Andromeda Galaxy in about five billion years.
“Technically, Andromeda will eat us because it’s the more massive one,” he said.
Almost all of the data for the research was collected with the
Anglo-Australian Telescope in New South Wales as part of the Galaxy And
Mass Assembly (GAMA) survey, led by Professor Simon Driver at ICRAR.
The GAMA survey involves more than 90 scientists and took seven years to complete.
This study is one of more than 60 publications to have come from the work, with another 180 in progress.
Dr Robotham said as galaxies grew they had more gravity and could therefore more easily pull in their neighbours.
He said the reason star formation slowed down in really massive
galaxies was thought to be because of extreme feedback events in a very
bright region at the centre of a galaxy known as an active galactic
“The topic is much debated, but a popular mechanism is where the
active galactic nucleus basically cooks the gas and prevents it from
cooling down to form stars,” Dr Robotham said.
Ultimately, gravity is expected to cause all the galaxies in bound
groups and clusters to merge into a few super-giant galaxies, although
we will have to wait many billions of years before that happens.
“If you waited a really, really, really long time that would
eventually happen but by really long I mean many times the age of the
Universe so far,” Dr Robotham said.
ICRAR is a joint venture between Curtin
University and The University of Western Australia with support and
funding from the State Government of Western Australia.
This picture, taken by the NASA/ESA Hubble Space Telescope’s Wide Field Planetary Camera 2 (WFPC2), shows a galaxy known as NGC 6872
in the constellation of Pavo (The Peacock). Its unusual shape is caused
by its interactions with the smaller galaxy that can be seen just above
NGC 6872, called IC 4970. They both lie roughly 300 million light-years
away from Earth.
From tip to tip, NGC 6872 measures over 500 000 light-years across,
making it the second largest spiral galaxy discovered to date. In terms
of size it is beaten only by NGC 262,
a galaxy that measures a mind-boggling 1.3 million light-years in
diameter! To put that into perspective, our own galaxy, the Milky Way,
measures between 100 000 and 120 000 light-years across, making NGC 6872
about five times its size.
The upper left spiral arm of NGC 6872 is visibly distorted and is
populated by star-forming regions, which appear blue on this image. This
may have been be caused by IC 4970 recently passing through this arm —
although here, recent means 130 million years ago! Astronomers have
noted that NGC 6872 seems to be relatively sparse in terms of free
hydrogen, which is the basis material for new stars, meaning that if it
weren’t for its interactions with IC 4970, NGC 6872 might not have been
able to produce new bursts of star formation.
A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Judy Schmidt.