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Figure 1:Jet and disk in the HH 212 protostellar system: (a) A
composite image for the jet in different molecules, produced by
combining the images from the Very Large Telescope (McCaughrean et al.
2002) and ALMA (Lee et al. 2015). Orange image around the center shows
the dusty envelope+disk at submillimeter wavelength obtained with ALMA
at 200 AU resolution. (b) A zoom-in to the very center for the dusty
disk at 8 AU resolution. Asterisks mark the possible position of the
central protostar. A dark lane is seen in the equator, causing the disk
to appear as a "hamburger". A size scale of our solar system is shown in
the lower right corner for size comparison. (c) An accretion disk model
that can reproduce the observed dust emission in the disk. Credit: ALMA (ESO/NAOJ/NRAO)/Lee et al.
An international research team, led by Chin-Fei Lee in Academia Sinica
Institute of Astronomy and Astrophysics (ASIAA, Taiwan), has made a new
high-fidelity image with the Atacama Large Millimeter/submillimeter
Array (ALMA), catching a protostar (baby star) being fed with a dusty
"Hamburger", which is a dusty accretion disk. This new image not only
confirms the formation of an accretion disk around a very young
protostar, but also reveals the vertical structure of the disk for the
first time in the earliest phase of star formation. It not only poses a
big challenge on some current theories of disk formation, but also
potentially brings us key insights on the processes of grain growth and
settling that are important to planet formation.
"It is so amazing to see such a detailed structure of a very young
accretion disk. For many years, astronomers have been searching for
accretion disks in the earliest phase of star formation, in order to
determine their structure, how they are formed, and how the accretion
process takes place. Now using the ALMA with its full power of
resolution, we not only detect an accretion disk but also resolve it,
especially its vertical structure, in great detail", says Chin-Fei Lee
"In the earliest phase of star formation, there are theoretical
difficulties in producing such a disk, because magnetic fields can slow
down the rotation of collapsing material, preventing such a disk from
forming around a very young protostar. This new finding implies that the
retarding effect of magnetic fields in disk formation may not be as
efficient as we thought before," says Zhi-Yun Li at University of
HH 212 is a nearby protostellar system in Orion at a distance of
about 1300 ly. The central protostar is very young with an age of only
~40,000 yrs (which is about 10 millionth of the age of Our Sun) and a
mass of ~0.2 Msun. It drives a powerful bipolar jet and thus must
accrete material efficiently. Previous search at a resolution of 200 AU
only found a flattened envelope spiraling toward the center and a hint
of a small dusty disk near the protostar. Now with ALMA at a resolution
of 8 AU, which is 25 times higher, we not only detect but also spatially
resolve the dusty disk at submillimeter wavelength.
The disk is nearly edge-on and has a radius of about 60 AU.
Interestingly, it shows a prominent equatorial dark lane sandwiched
between two brighter features, due to relatively low temperature and
high optical depth near the disk midplane. For the first time, this dark
lane is seen at submillimeter wavelength, producing a
"hamburger"-shaped appearance that is reminiscent of the scattered-light
image of an edge-on disk in optical and near infrared. The structure of
the dark lane clearly implies that the disk is flared, as expected in
an accretion disk model.
Our observations open up an exciting possibility of directly
detecting and characterizing small disks around the youngest protostars
through high-resolution imaging with ALMA, which provides strong
constraints on theories of disk formation. Our observations of the
vertical structure can also yield key insights on the processes of grain
growth and settling that are important to planet formation in the
Paper and research team
This research was presented in a paper "First Detection of Equatorial
Dark Dust Lane in a Protostellar Disk at Submillimeter Wavelength," by
Lee et al. to appear in the journal Science Advances.
The team is composed of Chin-Fei Lee (ASIAA, Taiwan; National Taiwan
University, Taiwan), Zhi-Yun Li (University of Virginia, USA), Paul T.P.
Ho (ASIAA, Taiwan; East Asia Observatory), Naomi Hirano (ASIAA,
Taiwan), Qizhou Zhang (Harvard-Smithsonian Center for Astrophysics,
USA), and Hsien Shang (ASIAA, Taiwan).
Thefigure aboveshows an artist's impression of an accretion disk
feeding the central protostar and a jet coming out from the protostar. Credit: Yin-Chih Tsai/ASIAA
Target pixel mask of Alcyone from Kepler image. The four squared-in pixels are used for the registration of the brightness of the star.
The white pixels are useless due to saturation.
Tim White as lead author and several other researchers related to SAC have a paper out in Monthly Notices of the Royal Astronomical Observatory, titled 'Beyond the Kepler/K2 bright limit: variability in the seven brightest members of the Pleiades'.
The astronomers will never be content! They strive to observe the faintest stars possible, and this means that some of the brighter stars are actually too bright to observe with modern equipment. A workaround to this has now been developed by an international group of astronomers led by Tim White of Stellar Astrophysics Centre, Aarhus University and the method has been tested successfully on the seven brightest stars in the open cluster named the Pleiades or the Seven Sisters.
Aiming a beam of light from a bright star at a point on a CCD detector will cause several of the central pixels of the star's image to be saturated, and the construction of the CCD will cause long ghost images of saturated pixels in various directions out from the center of the image. Saturation means a loss of precision in the measurement of the total brightness of the star. The solution is simple: the star is bright enough that you can skip all the saturated pixels, selecting a set of unsaturated positions on the CCD hit by enough light that you can still make a reliable measurement of the brightness variations that are of interest if you want to do asteroseismology, observing the regular short time variations or if you want to see if an exoplanet passes in front of the star causing the intensity to drop shortly.
This new method has been named halo photometry. It is simple and fast and it has been used by the authors for observing the seven brightest named stars in the open cluster using data from the extended K2 mission by the NASA Kepler satellite.
The Pleiades with the light curves of the seven brightest stars inserted. Maia is obviously the odd sister out.
The seven stars are closely of the same age and six of the show regular B-star pulsations. This is interesting for determining the values of some of the poorly understood processes in the core of these stars. The seventh star, Maia is different. It is not variable in any way comparable to the other bright stars in the cluster, but it does vary with a regular period of 10 days. Previous studies have shown that Maia belongs to a class of stars with a deficiency of both He and Hg, and the authors conclude that the variability is due to a large spot on the surface of the star of different chemical composition. This means that Maia itself does definitely not belong to the controversial group af stars named Maia variables, and the authors implore for the sanity of future astronomers that this designation should not be used anymore!
No signs of exoplanets were detected during the study.
This stunning cosmic pairing of the two
very different looking spiral galaxies NGC 4302 and NGC 4298 was imaged
by the NASA/ESA Hubble Space Telescope. The image brilliantly captures
their warm stellar glow and brown, mottled patterns of dust. As a
perfect demonstration of Hubble’s capabilities, this spectacular view
has been released as part of the telescope’s 27th anniversary
Since its launch on 24 April 1990, Hubble
has been nothing short of a revolution in astronomy. The first orbiting
facility of its kind, for 27 years the telescope has been exploring the
wonders of the cosmos. Astronomers and the public alike have witnessed
what no other humans in history have before. In addition to revealing
the beauty of the cosmos, Hubble has proved itself to be a treasure
chest of scientific data that astronomers can access.
ESA and NASA celebrate Hubble’s birthday each year with a spectacular image. This year’s anniversary image features a pair of spiral galaxies known as NGC 4302 — seen edge-on — and NGC 4298, both located 55 million light-years away in the northern constellation of Coma Berenices (Berenice’s Hair). The pair, discovered by astronomer William Herschel in 1784, form part of the Virgo Cluster, a gravitationally bound collection of nearly 2000 individual galaxies.
The edge-on NGC 4302 is a bit smaller than our own Milky Way Galaxy.
The tilted NGC 4298 is even smaller: only half the size of its
At their closest points, the galaxies are separated from each other
in projection by only around 7000 light-years. Given this very close
arrangement, astronomers are intrigued by the galaxies’ apparent lack of
any significant gravitational interaction; only a faint bridge of neutral hydrogen gas
— not visible in this image — appears to stretch between them. The long
tidal tails and deformations in their structure that are typical of
galaxies lying so close to each other are missing completely.
Astronomers have found very faint tails of gas streaming from the two
galaxies, pointing in roughly the same direction — away from the centre
of the Virgo Cluster. They have proposed that the galactic double is a
recent arrival to the cluster, and is currently falling in towards the
cluster centre and the galaxy Messier 87 lurking there — one of the most massive galaxies known. On their travels, the two galaxies are encountering hot gas — the intracluster medium — that acts like a strong wind, stripping layers of gas and dust from the galaxies to form the streaming tails.
Even in its 27th year of operation, Hubble continues to provide truly
spectacular images of the cosmos, and even as the launch date of its
companion — the NASA/ESA/CSA James Webb Space Telescope
— draws closer, Hubble does not slow down. Instead, the telescope keeps
raising the bar, showing it still has plenty of observing left to do
for many more years to come. In fact, astronomers are looking forward to
have Hubble and James Webb operational at the same time and use their
combined capabilities to explore the Universe.
The Hubble Space Telescope is a project of international cooperation between ESA and NASA.
Lensed supernova will give insight into the expansion of the Universe
A Swedish-led team of astronomers used
the NASA/ESA Hubble Space Telescope to analyse the multiple images of a
gravitationally lensed type Ia supernova for the first time. The four
images of the exploding star will be used to measure the expansion of
the Universe. This can be done without any theoretical assumptions about
the cosmological model, giving further clues about how fast the
Universe is really expanding. The results are published in the journal
An international team, led by astronomers from the Stockholm University, Sweden, has discovered a distant type Ia supernova, called iPTF16geu  — it took the light 4.3 billion years to travel to Earth .
The light from this particular supernova was bent and magnified by the
effect of gravitational lensing so that it was split into four separate
images on the sky .
The four images lie on a circle with a radius of only about 3000
light-years around the lensing foreground galaxy, making it one of the
gravitational lenses discovered so far. Its appearance resembles the
famous Refsdal supernova, which astronomers detected in 2015 (heic1525). Refsdal, however, was a core-collapse supernova.
Type Ia supernovae always have the same intrinsic brightness, so by measuring how bright they appear astronomers can determine how far away they are. They are therefore known as standard candles. These supernovae have been used for decades to measure distances across the Universe, and were also used to discover its accelerated expansion and infer the existence of dark energy. Now the supernova iPTF16geu allows scientists to explore new territory, testing the theories of the warping of spacetime on smaller extragalactic scales than ever before.
“Resolving, for the first time, multiple images of a strongly
lensed standard candle supernova is a major breakthrough. We can measure
the light-focusing power of gravity more accurately than ever before,
and probe physical scales that may have seemed out of reach until now,” says Ariel Goobar, Professor at the Oskar Klein Centre at Stockholm University and lead author of the study.
The critical importance of the object meant that the team instigated
follow-up observations of the supernova less than two months after its
discovery. This involved some of the world’s leading telescopes in
addition to Hubble: the Keck telescope on Mauna Kea, Hawaii, and ESO’s Very Large Telescope
in Chile. Using the data gathered, the team calculated the
magnification power of the lens to be a factor of 52. Because of the
standard candle nature of iPTF16geu, this is the first time this
measurement could be made without any prior assumptions about the form
of the lens or cosmological parameters.
Currently the team is in the process of accurately measuring how long
it took for the light to reach us from each of the four images of the
supernova. The differences in the times of arrival can then be used to
calculate the Hubble constant — the expansion rate of the Universe — with high precision .
This is particularly crucial in light of the recent discrepancy between
the measurements of its value in the local and the early Universe (heic1702).
As important as lensed supernovae are for cosmology, it is extremely
difficult to find them. Not only does their discovery rely on a very
particular and precise alignment of objects in the sky, but they are
also only visible for a short time. “The discovery of iPTF16geu is truly like finding a somewhat weird needle in a haystack,” remarks Rahman Amanullah, co-author and research scientist at Stockholm University. “It reveals to us a bit more about the Universe, but mostly triggers a wealth of new scientific questions.”
Studying more similarly lensed supernovae will help shape our
understanding of just how fast the Universe is expanding. The chances of
finding such supernovae will improve with the installation of new
survey telescopes in the near future.
 iPTF16geu was initially observed by the iPTF (intermediate Palomar Transient Factory) collaboration with thePalomar Observatory. This is a fully automated, wide-field survey delivering a systematic exploration of the optical transient sky.
 This corresponds to aredshift of 0.4. The lensing galaxy has a redshift of 0.2.
is a phenomenon that was first predicted by Albert Einstein in 1912. It
occurs when a massive object lying between a distant light source and
the observer bends and magnifies the light from the source behind it.
This allows astronomers to see objects that would otherwise be to faint
 For each image of the supernova,
the light is not bent in the same way. This results in slightly
different travel times. The maximum time delay between the four images
is predicted to be less than 35 hours.
The Hubble Space Telescope is a project of international cooperation between ESA and NASA.
This research was presented in a paper entitled “iPTF16geu: A
multiply-imaged gravitationally lensed Type Ia supernova” by Goobar et
al., which appeared in the journal Science.
The international team of astronomers in this study consists of A.
Goobar (The Oskar Klein Centre, Sweden), R. Amanullah (The Oskar Klein
Centre, Sweden), S. R. Kulkarni (Cahill Center for Astrophysics, USA),
P. E. Nugent (University of California, USA; Lawrence Berkeley National
Laboratory, USA), J. Johansson (Weizmann Institute of Science, Israel),
C. Steidel (Cahill Center for Astrophysics, USA), D. Law (Space
Telescope Science Institute, USA), E. Mörtsell (The Oskar Klein Centre,
Sweden), R. Quimby (San Diego State University, USA; Kavli IPMU (WPI),
Japan), N. Blagorodnova (Cahill Center for Astrophysics, USA), A.
Brandeker (Stockholm University, Sweden), Y. Cao (eScience Institute and
Department of Astronomy, USA), A. Cooray (University of California,
USA), R. Ferretti (The Oskar Klein Centre, Sweden), C. Fremling (The
Oskar Klein Centre, Sweden), L. Hangard (The Oskar Klein Centre,
Sweden), M. Kasliwal (Cahill Center for Astrophysics, USA), T. Kupfer
(Cahill Center for Astrophysics, USA), R. Lunnan (Cahill Center for
Astrophysics, USA; Stockholm University, Sweden), F. Masci (Infrared
Processing and Analysis Center, USA), A. A. Miller (Center for
Interdisciplinary Exploration and Research in Astrophysics (CIERA), USA;
The Adler Planetarium, USA) H. Nayyeri (University of California, USA),
J. D. Neill (Cahill Center for Astrophysics, USA), E. O. Ofek (Weizmann
Institute of Science, Israel), S. Papadogiannakis (The Oskar Klein
Centre, Sweden), T. Petrushevska (The Oskar Klein Centre, Sweden), V.
Ravi (Cahill Center for Astrophysics, USA), J. Sollerman (The Oskar
Klein Centre, Sweden), M. Sullivan (University of Southampton, UK), F.
Taddia (The Oskar Klein Centre, Sweden), R. Walters (Cahill Center for
Astrophysics, USA), D. Wilson (University of California, USA), L. Yan
(Cahill Center for Astrophysics, USA), O. Yaron (Weizmann Institute of
Image credit: NASA, ESA, Sloan Digital Sky Survey, W. M. Keck
Observatory, Palomar Observatory/California Institute of Technology.
This entrancing image shows a few of the tenuous
threads that comprise Sh2-308, a faint and wispy shell of gas located
5200 light-years away in the constellation of Canis Major (The Great Dog).
Sh2-308 is a large bubble-like structure wrapped around an extremely large, bright type of star known as a Wolf-Rayet Star
— this particular star is called EZ Canis Majoris. These type of stars
are among the brightest and most massive stars in the Universe, tens of
times more massive than our own Sun, and they represent the extremes of
stellar evolution. Thick
winds continually poured off the progenitors of such stars, flooding
their surroundings and draining the outer layers of the Wolf-Rayet
stars. The fast wind of a Wolf-Rayet star therefore sweeps up the
surrounding material to form bubbles of gas.
Canis Majoris is responsible for creating the bubble of Sh2-308 — the
star threw off its outer layers to create the strands visible here. The
intense and ongoing radiation from the star pushes the bubble out
further and further, blowing it bigger and bigger. Currently the edges
of Sh2-308 are some 60 light-years apart!
these cosmic bubbles are, they are fleeting. The same stars that form
them will also cause their death, eclipsing and subsuming them in
violent supernova explosions.
Artist’s impression of a trip to the super-Earth exoplanet LHS 1140b
Transiting rocky super-Earth found in habitable zone of quiet red dwarf star
An exoplanet orbiting a red dwarf star 40
light-years from Earth may be the new holder of the title “best place
to look for signs of life beyond the Solar System”. Using ESO’s HARPS
instrument at La Silla, and other telescopes around the world, an
international team of astronomers discovered a “super-Earth” orbiting in
the habitable zone around the faint star LHS 1140. This world is a
little larger and much more massive than the Earth and has likely
retained most of its atmosphere. This, along with the fact that it
passes in front of its parent star as it orbits, makes it one of the
most exciting future targets for atmospheric studies. The results will
appear in the 20 April 2017 issue of the journal Nature.
The newly discovered super-Earth LHS 1140b orbits in the habitable zone around a faint red dwarf star, named LHS 1140, in the constellation of Cetus (The Sea Monster) .
Red dwarfs are much smaller and cooler than the Sun and, although LHS
1140b is ten times closer to its star than the Earth is to the Sun, it
only receives about half as much sunlight from its star as the Earth and
lies in the middle of the habitable zone. The orbit is seen almost
edge-on from Earth and as the exoplanet passes in front of the star once
per orbit it blocks a little of its light every 25 days.
“This is the most exciting exoplanet I’ve seen in the past decade,” said lead author Jason Dittmann of the Harvard-Smithsonian Center for Astrophysics (Cambridge, USA). “We
could hardly hope for a better target to perform one of the biggest
quests in science — searching for evidence of life beyond Earth.”
"The present conditions of the red
dwarf are particularly favourable — LHS 1140 spins more slowly and
emits less high-energy radiation than other similar low-mass stars," explains team member Nicola Astudillo-Defru from Geneva Observatory, Switzerland .
For life as we know it to exist, a planet must have liquid
surface water and retain an atmosphere. When red dwarf stars are
young, they are known to emit radiation that can be damaging for
the atmospheres of the planets that orbit them. In this case, the
planet's large size means that a magma ocean could have existed on
its surface for millions of years. This seething ocean of lava
could feed steam into the atmosphere long after the star has
calmed to its current, steady glow, replenishing the planet with
The discovery was initially made with the MEarth facility, which detected the first telltale, characteristic dips in light as the exoplanet passed in front of the star. ESO’s HARPS
instrument, the High Accuracy Radial velocity Planet Searcher, then
made crucial follow-up observations which confirmed the presence of the
super-Earth. HARPS also helped pin down the orbital period and allowed
the exoplanet’s mass and density to be deduced .
The astronomers estimate the age of the planet to be at
least five billion years. They also deduced that it has a diameter 1.4
times larger than the Earth — almost 18 000 kilometres. But with a mass
around seven times greater than the Earth, and hence a much higher
density, it implies that the exoplanet is probably made of rock with a
dense iron core.
This super-Earth may be the best candidate yet for future
observations to study and characterise its atmosphere, if one exists.
Two of the European members of the team, Xavier Delfosse and Xavier
Bonfils both at the CNRS and IPAG in Grenoble, France, conclude: “The
LHS 1140 system might prove to be an even more important target for the
future characterisation of planets in the habitable zone than Proxima b
or TRAPPIST-1. This has been a remarkable year for exoplanet
In particular, observations coming up soon with the NASA/ESA Hubble Space Telescope
will be able to assess exactly how much high-energy radiation is
showered upon LHS 1140b, so that its capacity to support life can be
Further into the future — when new telescopes like ESO’s Extremely Large Telescope
are operating — it is likely that we will be able to make detailed
observations of the atmospheres of exoplanets, and LHS 1140b is an
exceptional candidate for such studies.
 The habitable zone is defined by the range of orbits around a
star, for which a planet possesses the appropriate temperature needed
for liquid water to exist on the planet’s surface.
 Although the planet is located in
the zone in which life as we know it could potentially exist, it
probably did not enter this region until approximately forty million
years after the formation of the red dwarf star. During this phase, the
exoplanet would have been subjected to the active and volatile past of
its host star. A young red dwarf can easily strip away the water from
the atmosphere of a planet forming within its vicinity, leading to arunaway greenhouse effectsimilar to that on Venus.
 This effort enabled other transit
events to be detected by MEarth so that the astronomers could nail down
the detection of the exoplanet once and for all.
 The planet around Proxima Centauri (eso1629)
is much closer to Earth, but it probably does not transit its star,
making it very difficult to determine whether it holds an atmosphere.
 Unlike the TRAPPIST-1 system (eso1706),
no other exoplanets around LHS 1140 have been found. Multi-planet
systems are thought to be common around red dwarfs, so it is possible
that additional exoplanets have gone undetected so far because they are
This research was presented in a paper entitled “A
temperate rocky super-Earth transiting a nearby cool star”, by J. A.
Dittmann et al. to appear in the journal Nature on 20 April 2017.
The team is composed of Jason A. Dittmann (Harvard
Smithsonian Center for Astrophysics, USA), Jonathan M. Irwin (Harvard
Smithsonian Center for Astrophysics, USA), David Charbonneau (Harvard
Smithsonian Center for Astrophysics, USA), Xavier Bonfils (Institut de
Planétologie et d'Astrophysique de Grenoble – Université
Grenoble-Alpes/CNRS, France), Nicola Astudillo-Defru (Observatoire de
Genève, Switzerland), Raphaëlle D. Haywood (Harvard Smithsonian Center
for Astrophysics, USA), Zachory K. Berta-Thompson (University of
Colorado, USA), Elisabeth R. Newton (MIT, USA), Joseph E. Rodriguez
(Harvard Smithsonian Center for Astrophysics, USA), Jennifer G. Winters
(Harvard Smithsonian Center for Astrophysics, USA), Thiam-Guan Tan
(Perth Exoplanet Survey Telescope, Australia), José-Manuel Almenara
(Institut de Planétologie et d'Astrophysique de Grenoble - Université
Grenoble-Alpes/CNRS, France; Observatoire de Genève, Switzerland),
François Bouchy (Aix Marseille Université, France), Xavier Delfosse
(Institut de Planétologie et d'Astrophysique de Grenoble – Université
Grenoble-Alpes / CNRS, France), Thierry Forveille (Institut de
Planétologie et d'Astrophysique de Grenoble – Université
Grenoble-Alpes/CNRS, France), Christophe Lovis (Observatoire de Genève,
Switzerland), Felipe Murgas (Institut de Planétologie et d'Astrophysique
de Grenoble – Université Grenoble-Alpes / CNRS, France; IAC, Spain),
Francesco Pepe (Observatoire de Genève, Switzerland), Nuno C. Santos
(Instituto de Astrofísica e Ciências do Espaço and Universidade do
Porto, Portugal), Stephane Udry (Observatoire de Genève, Switzerland),
Anaël Wünsche (CNRS/IPAG, France), Gilbert A. Esquerdo (Harvard
Smithsonian Center for Astrophysics, USA), David W. Latham (Harvard
Smithsonian Center for Astrophysics, USA) and Courtney D. Dressing
ESO is the foremost intergovernmental astronomy
organisation in Europe and the world’s most productive ground-based
astronomical observatory by far. It is supported by 16 countries:
Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland,
Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden,
Switzerland and the United Kingdom, along with the host state of Chile.
ESO carries out an ambitious programme focused on the design,
construction and operation of powerful ground-based observing facilities
enabling astronomers to make important scientific discoveries. ESO also
plays a leading role in promoting and organising cooperation in
astronomical research. ESO operates three unique world-class observing
sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO
operates the Very Large Telescope, the world’s most advanced
visible-light astronomical observatory and two survey telescopes. VISTA
works in the infrared and is the world’s largest survey telescope and
the VLT Survey Telescope is the largest telescope designed to
exclusively survey the skies in visible light. ESO is a major partner in
ALMA, the largest astronomical project in existence. And on Cerro
Armazones, close to Paranal, ESO is building the 39-metre Extremely
Large Telescope, the ELT, which will become “the world’s biggest eye on
At the center of the Centaurus galaxy cluster, there is a large elliptical galaxy called NGC 4696. Deeper still, there is a supermassive black hole buried within the core of this galaxy.
New data from NASA's Chandra X-ray Observatory and other telescopes has revealed details about this giant black hole, located some 145 million light years
from Earth. Although the black hole itself is undetected, astronomers
are learning about the impact it has on the galaxy it inhabits and the
larger cluster around it.
In some ways, this black hole resembles a beating heart that pumps
blood outward into the body via the arteries. Likewise, a black hole can
inject material and energy into its host galaxy and beyond.
By examining the details of the X-ray
data from Chandra, scientists have found evidence for repeated bursts
of energetic particles in jets generated by the supermassive black hole
at the center of NGC 4696. These bursts create vast cavities in the hot
gas that fills the space between the galaxies in the cluster. The bursts
also create shock waves, akin to sonic booms produced by high-speed airplanes, which travel tens of thousands of light years across the cluster.
This composite image contains X-ray data from Chandra (red) that reveals the hot gas in the cluster, and radio data
from the NSF's Karl G. Jansky Very Large Array (blue) that shows
high-energy particles produced by the black hole-powered jets. Visible
light data from the Hubble Space Telescope (green) show galaxies in the
cluster as well as galaxies and stars outside the cluster.
processing scale: This image shows a larger field of view than the main
composite image above and is about 122,000 light years across. This
image has also been rotated slightly clockwise to the main composite
Astronomers employed special processing to the X-ray data (shown
above) to emphasize nine cavities visible in the hot gas. These cavities
are labeled A through I in an additional image, and the location of the
black hole is labeled with a cross. The cavities that formed most
recently are located nearest to the black hole, in particular the ones
labeled A and B.
The researchers estimate that these black hole bursts, or "beats",
have occurred every five to ten million years. Besides the vastly
differing time scales, these beats also differ from typical human
heartbeats in not occurring at particularly regular intervals.
Curved processing scale: This image also shows a larger field of view than the main composite image and is about 550,000 light years across. This image has also been rotated slightly clockwise to the main composite image.
A different type of processing of the X-ray data (shown above)
reveals a sequence of curved and approximately equally spaced features
in the hot gas. These may be caused by sound waves generated by the
black hole's repeated bursts. In a galaxy cluster, the hot gas that
fills the cluster enables sound waves — albeit at frequencies far too
low for the human hear to detect — to propagate. (Note that both images
showing the labeled cavities and this image are rotated slightly
clockwise to the main composite.)
The features in the Centaurus Cluster are similar to the ripples seen in the Perseus cluster of galaxies.
The pitch of the sound in Centaurus is extremely deep, corresponding to
a discordant sound about 56 octaves below the notes near middle C. This
corresponds to a slightly higher (by about one octave) pitch than the
sound in Perseus. Alternative explanations for these curved features
include the effects of turbulence or magnetic fields.
The black hole bursts also appear to have lifted up gas that has been enriched in elements generated in supernova
explosions. The authors of the study of the Centaurus cluster created a
map showing the density of elements heavier than hydrogen and helium.
The brighter colors in the map show regions with the highest density of
heavy elements and the darker colors show regions with a lower density
of heavy elements. Therefore, regions with the highest density of heavy
elements are located to the right of the black hole. A lower density of
heavy elements near the black hole is consistent with the idea that
enriched gas has been lifted out of the cluster's center by bursting
activity associated with the black hole. The energy produced by the
black hole is also able to prevent the huge reservoir of hot gas from
cooling. This has prevented large numbers of stars from forming in the
A paper describing these results was published in the March 21st 2016
issue of the Monthly Notices of the Royal Astronomical Society and is available online. The first author is Jeremy Sanders from the Max Planck Institute for Extraterrestrial Physics in Garching, Germany.
NASA's Marshall Space Flight Center in Huntsville, Alabama, manages
the Chandra program for NASA's Science Mission Directorate in
Washington. The Smithsonian Astrophysical Observatory in Cambridge,
Massachusetts, controls Chandra's science and flight operations.
Scale: Image is about 2.2 arcmin across (about 93,000 light years) Category:Black Holes, Normal Galaxies & Starburst Galaxies Coordinates (J2000): RA 12h 48m 48.90s | Dec -41° 18′ 44.40 Constellation: Centaurus Observation Date: 15 pointings between May 2000 and June 2014 Observation Time: 216 hours 29 min (9 days 29 min) Obs. ID: 504, 505, 4190, 4191, 4954, 4955, 5310, 16223-16225, 16534, 16607-16610 Instrument:ACIS References: Sanders, J. et al., 2016, MNRAS, 457, 82; arXiv:1601.01489 Color Code: X-ray (Red); Optical (Green); Radio (Blue) Distance Estimate: About 145 million light years
Figure 1. ALMA image of the planetary body 2014 UZ224,
more informally known as DeeDee. At three times the distance of Pluto
from the Sun, DeeDee is the second most distant confirmed TNO with a
confirmed orbit in our solar system.
Figure 2.Size comparisons of objects in our solar system, including the recently discovered planetary body 'DeeDee.'
Credit: Alexandra Angelich (NRAO/AUI/NSF)
Figure 3.Orbits of objects in our solar system, showing the current location of the planetary body 'DeeDee'.
Credit: Alexandra Angelich (NRAO/AUI/NSF)
Figure 4. Artist concept of the planetary body 2014 UZ224,
more informally known as DeeDee. ALMA was able to observe the faint
millimeter-wavelength "glow" emitted by the object, confirming it is
roughly 635 kilometers across. At this size, DeeDee should have enough
mass to be spherical, the criteria necessary for astronomers to consider
it a dwarf planet, though it has yet to receive that official
designation. Credit: Alexandra Angelich (NRAO/AUI/NSF)
Using the Atacama Large Millimeter/submillimeter Array (ALMA),
astronomers have revealed extraordinary details about a recently
discovered far-flung member of our solar system, the planetary body 2014
UZ224, more informally known as DeeDee.
At about three times the current distance of Pluto from the Sun,
DeeDee is the second most distant known trans-Neptunian object (TNO)
with a confirmed orbit, surpassed only by the dwarf planet Eris.
Astronomers estimate that there are tens-of-thousands of these icy
bodies in the outer solar system beyond the orbit of Neptune.
The new ALMA data reveal, for the first time, that DeeDee is roughly
635 kilometers across, or about two-thirds the diameter of the dwarf
planet Ceres, the largest member of our asteroid belt. At this size,
DeeDee should have enough mass to be spherical, the criteria necessary
for astronomers to consider it a dwarf planet, though it has yet to
receive that official designation.
"Far beyond Pluto is a region surprisingly rich with planetary
bodies. Some are quite small but others have sizes to rival Pluto, and
could possibly be much larger," said David Gerdes, a scientist with the
University of Michigan and lead author on a paper appearing in the Astrophysical Journal Letters.
"Because these objects are so distant and dim, it's incredibly
difficult to even detect them, let alone study them in any detail. ALMA,
however, has unique capabilities that enabled us to learn exciting
details about these distant worlds."
Currently, DeeDee is about 92 astronomical units (AU) from the Sun.
An astronomical unit is the average distance from the Earth to the Sun,
or about 150 million kilometers. At this tremendous distance, it takes
DeeDee more than 1,100 years to complete one orbit. Light from DeeDee
takes nearly 13 hours to reach Earth.
Gerdes and his team announced the discovery of DeeDee in the fall of
2016. They found it using the 4-meter Blanco telescope at the Cerro
Tololo Inter-American Observatory in Chile as part of ongoing
observations for the Dark Energy Survey, an optical survey of about 12
percent of the sky that seeks to understand the as-yet mysterious force
that is accelerating the expansion of the universe.
he Dark Energy Survey produces vast troves of astronomical images,
which give astronomers the opportunity to also search for distant solar
system objects. The initial search, which includes nearly 15,000 images,
identified more than 1.1 billion candidate objects. The vast majority
of these turned out to be background stars and even more distant
galaxies. A small fraction, however, were observed to move slowly across
the sky over successive observations, the telltale sign of a TNO.
One such object was identified on 12 separate images. The astronomers
informally dubbed it DeeDee, which is short for Distant Dwarf.
The optical data from the Blanco telescope enabled the astronomers to
measure DeeDee's distance and orbital properties, but they were unable
to determine its size or other physical characteristics. It was possible
that DeeDee was a relatively small member of our solar system, yet
reflective enough to be detected from Earth. Or, it could be uncommonly
large and dark, reflecting only a tiny portion of the feeble sunlight
that reaches it; both scenarios would produce identical optical data.
Since ALMA observes the cold, dark universe, it is able to detect the
heat - in the form of millimeter-wavelength light - emitted naturally
by cold objects in space. The heat signature from a distant solar system
object would be directly proportional to its size.
"We calculated that this object would be incredibly cold, only about
30 degrees Kelvin, just a little above absolute zero," said Gerdes.
While the reflected visible light from DeeDee is only about as bright
as a candle seen halfway the distance to the moon, ALMA was able to
quickly home in on the planetary body’s heat signature and measure its
brightness in millimeter-wavelength light.
This allowed astronomers to determine that it reflects only about 13
percent of the sunlight that hits it. That is about the same
reflectivity of the dry dirt found on a baseball infield.
By comparing these ALMA observations to the earlier optical data, the
astronomers had the information necessary to calculate the object's
size. "ALMA picked it up fairly easily," said Gerdes.
"We were then able
to resolve the ambiguity we had with the optical data alone."
Objects like DeeDee are cosmic leftovers from the formation of the
solar system. Their orbits and physical properties reveal important
details about the formation of planets, including Earth.
This discovery is also exciting because it shows that it is possible
to detect very distant, slowly moving objects in our own solar system.
The researchers note that these same techniques could be used to detect
the hypothesized "Planet Nine" that may reside far beyond DeeDee and
"There are still new worlds to discover in our own cosmic backyard,"
concludes Gerdes. "The solar system is a rich and complicated place."
Despite all efforts galaxy formation and evolution are still far from being fully understood. Fortunately, the conditions we see within certain galaxies — such as so-called starburst galaxies — can tell us a lot about how they have evolved over time. Starburst galaxies contain a region (or many regions) where stars are forming at such a breakneck rate that the galaxy is eating up its gas supply faster than it can be replenished!
NGC 4536 is such a galaxy, captured here in beautiful detail by the Hubble’s Wide Field Camera 3 (WFC3). Located roughly 50 million light-years away in the constellation of Virgo (The Virgin), it is a hub of extreme star formation. There are several different factors that can lead to such an ideal environment in which stars can form at such a rapid rate. Crucially, there has to be a sufficiently massive supply of gas. This might be acquired in a number of ways — for example by passing very close to another galaxy, in a full-blown galactic collision, or as a result of some event that forces lots of gas into a relatively small space.
Star formation leaves a few tell-tale fingerprints, so astronomers can tell where stars have been born. We know that starburst regions are rich in gas. Young stars in these extreme environments often live fast and die young, burning extremely hot and exhausting their gas supplies fairly quickly. These stars also emit huge amounts of intense ultraviolet light, which blasts the electrons off any atoms of hydrogen lurking nearby (a process called ionisation), leaving behind clouds of ionised hydrogen (known in astronomer-speak as HII regionshttps://en.wikipedia.org/wiki/H_II_region).
Dark matter filaments bridge the space between galaxies in this false colour map. The locations of bright galaxies are shown by the white regions and the presence of a dark matter filament bridging the galaxies is shown in red. Credit: S. Epps & M. Hudson / University of Waterloo
The composite image, which combines a
number of individual images, confirms predictions that galaxies across
the universe are tied together through a cosmic web connected by dark
matter that has until now remained unobservable.
a mysterious substance that comprises around 25 per cent of the
universe, doesn’t shine, absorb or reflect light, which has
traditionally made it largely undetectable, except through gravity.
“For decades, researchers have been
predicting the existence of dark-matter filaments between galaxies that
act like a web-like superstructure connecting galaxies together,” said
Mike Hudson, a professor of astronomy at the University of Waterloo.
“This image moves us beyond predictions to something we can see and
As part of their research, Hudson and
co-author Seth Epps, a master’s student at the University of Waterloo at
the time, used a technique called weak gravitational lensing,
an effect that causes the images of distant galaxies to warp slightly
under the influence of an unseen mass such as a planet, a black hole, or
in this case, dark matter. The effect was measured in images from a
multi-year sky survey at the Canada-France-Hawaii Telescope.
They combined lensing images from more
than 23,000 galaxy pairs located 4.5 billion light-years away to create
a composite image or map that shows the presence of dark matter between
the two galaxies. Results show the dark matter filament bridge is
strongest between systems less than 40 million light years apart.
“By using this technique, we’re not
only able to see that these dark matter filaments in the universe exist,
we’re able to see the extent to which these filaments connect galaxies
together,” said Epps.
“The weak-lensing masses of filaments between luminous red galaxies” by Epps & Hudson was published in Monthly Notices of the Royal Astronomical Society (paper available here: https://doi.org/10.1093/mnras/stx517).
Notes for editors
The Royal Astronomical Society (RAS, www.ras.org.uk), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4,000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.
The RAS accepts papers for its journals based on the principle of peer review, in which fellow experts on the editorial boards accept the paper as worth considering. The Society issues press releases based on a similar principle, but the organisations and scientists concerned have overall responsibility for their content.
With two suns in its sky, Luke Skywalker's home planet Tatooine in
"Star Wars" looks like a parched, sandy desert world. In real life,
thanks to observatories such as NASA's Kepler space telescope, we know
that two-star systems can indeed support planets, although planets
discovered so far around double-star systems are large and gaseous.
Scientists wondered: If an Earth-size planet were orbiting two suns,
could it support life?
It turns out, such a planet could be quite hospitable if located at
the right distance from its two stars, and wouldn't necessarily even
have deserts. In a particular range of distances from two sun-like host
stars, a planet covered in water would remain habitable and retain its
water for a long time, according to a new study in the journal Nature
"This means that double-star systems of the type studied here are
excellent candidates to host habitable planets, despite the large
variations in the amount of starlight hypothetical planets in such a
system would receive," said Max Popp, associate research scholar at
Princeton University in New Jersey, and the Max Planck Institute of
Meteorology in Hamburg, Germany.
Popp and Siegfried Eggl, a Caltech postdoctoral scholar at NASA's Jet
Propulsion Laboratory, Pasadena, California, created a model for a
planet in the Kepler 35 system. In reality, the stellar pair Kepler 35A
and B host a planet called Kepler 35b, a giant planet about eight times
the size of Earth, with an orbit of 131.5 Earth days. For their study,
researchers neglected the gravitational influence of this planet and
added a hypothetical water-covered, Earth-size planet around the Kepler
35 AB stars. They examined how this planet's climate would behave as it
orbited the host stars with periods between 341 and 380 days.
"Our research is motivated by the fact that searching for potentially
habitable planets requires a lot of effort, so it is good to know in
advance where to look," Eggl said. "We show that it's worth targeting
In exoplanet research, scientists speak of a region called the
"habitable zone," the range of distances around a star where a
terrestrial planet is most likely to have liquid water on its surface.
In this case, because two stars are orbiting each other, the habitable
zone depends on the distance from the center of mass that both stars are
orbiting. To make things even more complicated, a planet around two
stars would not travel in a circle; instead, its orbit would wobble
through the gravitational interaction with the two stars.
Popp and Eggl found that on the far edge of the habitable zone in the
Kepler 35 double-star system, the hypothetical water-covered planet
would have a lot of variation in its surface temperatures. Because such a
cold planet would have only a small amount of water vapor in its
atmosphere, global average surface temperatures would swing up and down
by as much as 3.6 degrees Fahrenheit (2 degrees Celsius) in the course
of a year.
"This is analogous to how, on Earth, in arid climates like deserts,
we experience huge temperature variations from day to night," Eggl said.
"The amount of water in the air makes a big difference."
But, closer to the stars, near the inner edge of the habitable zone,
the global average surface temperatures on the same planet stay almost
constant. That is because more water vapor would be able to persist in
the atmosphere of the hypothetical planet and act as a buffer to keep
surface conditions comfortable.
As with single-star systems, a planet beyond the outer edge of the
habitable zone of its two suns would eventually end up in a so-called
"snowball" state, completely covered with ice. Closer than the inner
edge of the habitable zone, an atmosphere would insulate the planet too
much, creating a runaway greenhouse effect and turning the planet into a
Venus-like world inhospitable to life as we know it.
Another feature of the study's climate model is that, compared to
Earth, a water-covered planet around two stars would have less cloud
coverage. That would mean clearer skies for viewing double sunsets on
these exotic worlds.
NASA's planet-hunting Kepler telescope is managed by NASA's Ames Research Center in Silicon Valley. JPL, a divison of Caltech, managed Kepler mission development.