Messier 66 by Hubble

Hubble has snapped a spectacular view of the largest "player" in the Leo Triplet, a galaxy with an unusual anatomy: it displays asymmetric spiral arms and an apparently displaced core. The peculiar anatomy is most likely caused by the gravitational pull of the other two members of the trio.

The unusual spiral galaxy, Messier 66, is located at a distance of about 35 million light-years in the constellation of Leo. Together with Messier 65 and NGC 3628, Messier 66 is one third of the Leo Triplet, a trio of interacting spiral galaxies, part of the larger Messier 66 group. Messier 66 wins out in size over its fellow triplets - it is about 100 000 light-years across.

Messier 66 is the proud owner of exclusive asymmetric spiral arms which seem to climb above the galaxy's main disc and an apparently displaced nucleus. This asymmetry is unusual; most often, dense waves of gas, dust and newly born stars wind about the galaxy's center in a symmetric way. Astronomers believe that Messier 66's once orderly shape has most likely been distorted by the gravitational pull of its two neighbors.

Hubble has imaged Messier 66's striking dust lanes and bright star clusters along the spiral arms in fine detail with the Advanced Camera for Surveys. Star clusters - pictured in the blue and pinkish regions of the image - are key tools for astronomers since they are used as indicators of how the parent galaxies assembled over time.

Messier 66 boasts a remarkable record of supernovae explosions. The spiral galaxy has hosted three supernovae since 1989, the latest one occurring in 2009. A supernova is a stellar explosion that may momentarily outshine its entire host galaxy. It then fades away over a period lasting several weeks or months. During its very short life the supernova radiates as much energy as the Sun would radiate over a period of about 10 thousand million years.

Photo credit: NASA, ESA and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration. Acknowledgment: Davide De Martin and Robert Gendler

The Rosette Nebula by Herschel

This image from the Herschel Space Observatory shows most the cloud associated with the Rosette nebula, a stellar nursery about 5,000 light-years from Earth in the Monoceros, or Unicorn, constellation. Herschel collects the infrared light given out by dust. The bright smudges are dusty cocoons containing massive embryonic stars, which will grow up to 10 times the mass of our sun. The small spots near the center of the image are lower mass stellar embryos. The Rosette nebula itself, and its massive cluster of stars, is located to the right of the picture.

This image is a three-color composite showing infrared wavelengths of 70 microns (blue), 160 microns (green), and 250 microns (red). It was made with observations from Herschel's Photoconductor Array Camera and Spectrometer and the Spectral and Photometric Imaging Receiver instruments.

Photo credit: ESA and the PACS, SPIRE & HSC consortia, F. Motte (AIM Saclay,CEA/IRFU - CNRS/INSU - U.ParisDidedrot) for the HOBYS key programme

Dione and Titan

Saturn's moon Dione passes in front of the larger moon Titan, as seen from the Cassini spacecraft.

This image is part of a mutual event sequence in which one moon passes close to or in front of another. Such observations help scientists refine their understanding of the orbits of Saturn's moons. See PIA11692 to watch a movie of a mutual event.

Lit terrain seen here is on the anti-Saturn side of Dione (1,123 kilometers, or 698 miles across) and the leading hemisphere of Titan (5,150 kilometers, or 3,200 miles across).

The image was taken in visible blue light with the Cassini spacecraft narrow-angle camera on March 12, 2010. The view was obtained at a distance of approximately 2.2 million kilometers (1.4 million miles) from Dione and 3.6 million kilometers (2.2 million miles) from Titan. Scale in the original image was 13 kilometers (8 miles) per pixel on Dione and on 21 kilometers (13 miles) per pixel Titan. The image has been magnified by a factor of 1.5 and contrast-enhanced to aid visibility.

Photo credit: NASA/JPL/Space Science Institute

Graben and Pyroclastics in SW Mare Humorum

Two small black arrows on today's image show the location of a small graben. A degraded impact crater (108 m in diameter) can be seen centered on the graben between the arrows. Graben are extensional tectonic features formed by the downward movement of a crustal block between two normal faults. This small graben is parallel to a much larger graben (Rima Doppelmayer I) which is 1100 m wide and located only 800 m to the west. You can also see other small graben that are parallel to Rima Doppelmayer I. All of these graben may have formed during the episode of regional extension associated with the final filling of Mare Humorum with dense mare basalt deposits.

Finally, it should be noted that the entire area shown in the image is mantled by a relatively thick (greater than 10 m) deposit of pyroclastic glass. It has been suggested that pyroclastic debris would be an excellent lunar resource, and that pyroclastic deposits would be prime sites for the establishment of lunar bases.

Photo credit: NASA/GSFC/Arizona State University

IC 342 by WISE

The spiral beauty, called IC 342 and sometimes the "hidden galaxy," is shrouded behind our own galaxy, the Milky Way. Stargazers and professional astronomers have a hard time seeing the galaxy through the Milky Way's bright band of stars, dust and gas. WISE's infrared vision cuts through this veil, offering a crisp view.

In a spiral galaxy like IC 342, dust and gas are concentrated in the arms. The denser pockets of gas trigger the formation of new stars, as represented here in green and yellow. The core, shown in red, is also bursting with young stars, which are heating up dust. Stars that appear blue reside within our Milky Way, between us and IC 342.

This galaxy has been of great interest to astronomers because it is relatively close. However, determining its distance from Earth has proven difficult due to the intervening Milky Way. Astronomer Edwin Hubble first thought the galaxy might belong to our own Local Group of galaxies, but current estimates now place it farther away, at about 6.6 to 11 million light-years.

This image was made from observations by all four infrared detectors aboard WISE. Blue and cyan represent infrared light at wavelengths of 3.4 and 4.6 microns, which is primarily light from stars. Green and red represent light at 12 and 22 microns, which is primarily emission from warm dust.

Photo credit: NASA/JPL-Caltech/UCLA

Lava Flows on Venus' Idunn Mons

This figure shows the volcanic peak Idunn Mons (at 46 degrees south latitude, 214.5 degrees east longitude) in the Imdr Regio area of Venus. The topographic backbone derives from data obtained by NASA's Magellan spacecraft, with a vertical exaggeration of 30 times. Radar data (in brown) from Magellan has been draped on top of the topographic data. Bright areas are rough or have steep slopes. Dark areas are smooth.

The colored overlay [above] shows the heat patterns derived from surface brightness data collected by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS), aboard the European Space Agency's Venus Express spacecraft. Temperature variations due to topography were removed. The brightness signals the composition of the minerals that were changed due to lava flow. Red-orange is the warmest area and purple is the coolest. The warmest area is centered on the summit, which stands about 2.5 kilometers (1.6 miles) above the plains, and the bright flows that originate there. Idunn Mons has a diameter of about 200 kilometers (120 miles).

The spectrometer data was collected from May 2006 to the end of 2007. A movie featuring 360-degree views of the volcano is based on the same data and can be viewed at JPL's Multimedia.

Photo credit: NASA/JPL-Caltech/ESA

Note: For more information, see New Evidence for Recent Volcanism on Venus, at the ESA/Venus Express website.

Dione's Wispy Terrain

Wispy terrain winds across the trailing hemisphere of Saturn's moon Dione in this Cassini view taken during the spacecraft's Jan. 27, 2010 non-targeted flyby.

Cassini came within about 45,000 kilometers (28,000 miles) of the moon during this flyby, but this image was acquired at a distance of approximately 137,000 kilometers (85,000 miles) from Dione. See PIA06163 for an older, closer view of Dione's wispy fractures. This view looks toward the anti-Saturn side and trailing hemisphere of Dione (1,123 kilometers, or 698 miles across). North on Dione is up.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 27, 2010. The view was obtained at a Sun-Dione-spacecraft, or phase, angle of 38 degrees. Image scale is 819 meters (2,687 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Each Crater Tells a Story

Browsing around the Flamsteed Constellation region of interest, you might notice that a lot of the craters here have odd features, including flat floors, raised floors, or rings that look like one crater nested within another. In the image above, the crater in the middle top displays a ring within its main (degraded) rim, and the crater just below it has a flat floor, compared to the typical bowl-shaped craters in the surroundings. These type of features occur when a crater forms partly in rocky material and partly in regolith. The term regolith refers to all of the fragmental material - dust and rocks of all sizes - that covers the Moon's surface and is created by impact events which continually pulverize the bedrock. When planning for lunar surface activities, engineers were concerned that this dusty, sandy surface wouldn't be stable for the spacecraft and Apollo astronauts that were to land there, so scientists worked out methods to estimate the thickness of the regolith ahead of time. Using images from Lunar Orbiter and laboratory experiments with a high-velocity vertical gun, a relationship between regolith thickness and the shape of a crater was developed. If the regolith is thin compared to the depth of the crater, the crater forms an inner ring. If the regolith is a little thicker, the crater develops a flat floor, and if thicker still then the crater is bowl-shaped.

WAC [Wide Area Camera] monochrome observation of the Flamsteed Constellation region of interest. Arrow indicates location of NAC [Narrow Area Camera] image above and Flamsteed crater (20 km in diameter) is at the lower left. Scene width is 87 km; image M117779352ME [NASA/GSFC/Arizona State University].

The crater shapes in the Flamsteed Constellation region of interest demonstrate that the regolith is very thin (on average just a couple meters thick). This is because this is the site of some of the youngest volcanism on the Moon, and since the surface is younger, it hasn't had as much time to get beat up by impacts. Visiting this site with human explorers would provide a good opportunity to sample the bedrock beneath this thin regolith, and could give insight into the duration of volcanic activity on the Moon, and the evolution of lunar volcanism as the Moon aged and cooled. Astronauts could also visit the nearby Surveyor 1 site and check on the condition of America's first soft lander.

Photo credit: NASA/GSFC/Arizona State University

Shiveluch Volcano Erupting

Shiveluch Volcano in Kamchatka, Siberia, Russia, is one of the frequently active volcanoes located in eastern Siberia. In this composite image, brownish ash covers the southern part of the mountain, under an ash-laden vertical eruption plume. Red areas are hot-spots seen on ASTER's thermal infrared bands, and are related to lava flows. The image was acquired March 26, 2010, and is located at 56.6 degrees north latitude, 161.3 degrees east longitude. The image covers an area of 17.7 x 21.2 km.

Photo credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

Saturn Ring Spokes and the Shadow of Mimas

Bright spokes and the shadow of a moon grace Saturn's B ring in this Cassini spacecraft image.

Spokes are radial markings scientists continue to study, and they can be seen here stretching from the far left to upper right of the image. Spokes appear bright when they are viewed at phase, or Sun-Saturn-spacecraft, angles higher than about 45 degrees. This image was taken at a phase angle of 50 degrees. See PIA11144 and PIA08288 to learn more.

The moon Mimas is not shown here, but its shadow appears on the rings near the top of the image. The novel illumination geometry that accompanies equinox lowers the sun's angle to the ringplane, significantly darkens the rings, and causes out-of-plane structures to look anomalously bright and cast shadows across the rings. These scenes are possible only during the few months before and after Saturn's equinox, which occurs only once in about 15 Earth years. Before and after equinox, Cassini's cameras have spotted not only the predictable shadows of some of Saturn's moons (see PIA11657), but also the shadows of newly revealed vertical structures in the rings themselves (see PIA11665).

This view looks toward the northern, sunlit side of the rings from about 9 degrees above the ringplane. The image was taken using a compression scheme that reduces the image file size on the spacecraft's data recorder, resulting in the rings' slightly pixelated appearance.

The image was taken in visible light with the Cassini spacecraft wide-angle camera on Jan. 11, 2010. The view was acquired at a distance of approximately 611,000 kilometers (380,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 50 degrees. Image scale is 66 kilometers (41 miles) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Soul Nebula (IC 1848-W5) by WISE

This WISE mosaic is of the Soul Nebula (a.k.a. the Embryo Nebula, IC 1848, or W5). It is an open cluster of stars surrounded by a cloud of dust and gas over 150 light-years across and located about 6,500 light-years from Earth in the constellation Cassiopeia, near the Heart Nebula (partially seen in the WISE image of Maffei 1 & 2).

The cluster of stars, IC 1848, formed about a million years ago from the material of the nebula. Winds and ultraviolet light from these young stars are excavating a cavity in the cloud. Parts of the cloud that are more dense than their surroundings are being eroded more slowly and form giant towers, or pillars of dust and gas, which all point toward the central star cluster. It's reminiscent of the landscape of Badlands National Park in South Dakota. Material at the interior edges of the cavity is also being compressed by the winds and radiation from the star cluster. This triggers new star formation in those areas. The pillars inside the Soul Nebula are each about 10 light-years tall and have stars forming at their tips.

All four infrared detectors aboard WISE were used to make this image. Color is representational: blue and cyan represent infrared light at wavelengths of 3.4 and 4.6 microns, which is primarily light from stars. Green and red represent light at 12 and 22 microns, which is primarily emission from warm dust.

Photo credit: NASA/JPL-Caltech/UCLA

Yin Yang Iapetus

The two-toned surface of Saturn's moon Iapetus is demonstrated in the dark region of the moon visible on the top left and the bright crater in the lower right of this Cassini portrait.

See PIA11690 to learn more about the brightness dichotomy on Iapetus.

The moon's oblate shape is also visible here. This view looks toward the Saturn-facing side of Iapetus (1,471 kilometers, or 914 miles across). North on Iapetus is up and rotated 35 degrees to the right.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Feb. 23, 2010. The view was obtained at a distance of approximately 1.6 million kilometers (994,000 miles) from Iapetus and at a Sun-Iapetus-spacecraft, or phase, angle of 51 degrees. Image scale is 9 kilometers (6 miles) per pixel.

Photo credit: NASA/JPL/Space Science Institute

The Trapezium Cluster in the Orion Nebula

A colony of hot, young stars is stirring up the cosmic scene in this new picture from NASA's Spitzer Space Telescope. The image shows the Orion nebula, a happening place where stars are born. The young stars dip and peak in brightness due to a variety of reasons. Shifting cold and hot spots on the stars' surfaces cause brightness levels to change, in addition to surrounding disks of lumpy planet-forming material, which can obstruct starlight. Spitzer is keeping tabs on the young stars, providing data on their changing ways.

The hottest stars in the region, called the Trapezium cluster, are bright spots at center right. Radiation and winds from those stars has sculpted and blown away surrounding dust. The densest parts of the cloud appear dark at center left.

This image was taken after Spitzer's liquid coolant ran dry in May 2009, marking the beginning of its "warm" mission. Light from the telescope's remaining infrared channels has been color-coded: 3.6-micron light is blue and 4.5-micron light is orange.

Photo credit: NASA/JPL-Caltech

All-Sky Map of Infrared Sources by AKIRA

This AKARI view of the sky shows infrared sources at 9 micrometers in blue, at 18 micrometers in green, and at 90 micrometers in red. The image is arranged with the Galactic Center in the middle, and the plane of the Galaxy running horizontally across the map. Emission from the photospheres of stars dominates the 9 micrometers catalog, where the galactic disc and nuclear bulge are clearly visible, whereas dust and star formation in the disc of our Galaxy become are more prominent at 90 micrometers. Away from the Galactic Plane, many extragalactic objects are detected, tracing galaxy evolution and star formation in the distant Universe.

Photo credit: JAXA

For more information, read ESA: AKARI Produces Two New Infrared All-Sky Catalogs.

Hubble Confirms Cosmic Acceleration with Weak Lensing

A new study led by European scientists presents the most comprehensive analysis of data from the most ambitious survey ever undertaken by the NASA/ESA Hubble Space Telescope. These researchers have, for the first time ever, used Hubble data to probe the effects of the natural gravitational "weak lenses" in space and characterize the expansion of the Universe.

A group of astronomers, led by Tim Schrabback of the Leiden Observatory, conducted an intensive study of over 446,000 galaxies within the COSMOS field, the result of the largest survey ever conducted with Hubble. In making the COSMOS survey, Hubble photographed 575 slightly overlapping views of the same part of the Universe using the Advanced Camera for Surveys (ACS) on board Hubble. It took nearly 1,000 hours of observations.

In addition to the Hubble data, researchers used redshift [1] data from ground-based telescopes to assign distances to 194,000 of the galaxies surveyed (out to a redshift of 5). "The sheer number of galaxies included in this type of analysis is unprecedented, but more important is the wealth of information we could obtain about the invisible structures in the Universe from this exceptional dataset," says co-author Patrick Simon from Edinburgh University.

In particular, the astronomers could "weigh" the large-scale matter distribution in space over large distances. To do this, they made use of the fact that this information is encoded in the distorted shapes of distant galaxies, a phenomenon referred to as weak gravitational lensing [2]. Using complex algorithms, the team led by Schrabback has improved the standard method and obtained galaxy shape measurements to an unprecedented precision. The results of the study will be published in an upcoming issue of Astronomy and Astrophysics.

The meticulousness and scale of this study enables an independent confirmation that the expansion of the Universe is accelerated by an additional, mysterious component named dark energy. A handful of other such independent confirmations exist. Scientists need to know how the formation of clumps of matter evolved in the history of the Universe to determine how the gravitational force, which holds matter together, and dark energy, which pulls it apart by accelerating the expansion of the Universe, have affected them. "Dark energy affects our measurements for two reasons. First, when it is present, galaxy clusters grow more slowly, and secondly, it changes the way the Universe expands, leading to more distant - and more efficiently lensed - galaxies. Our analysis is sensitive to both effects," says co-author Benjamin Joachimi from the University of Bonn. "Our study also provides an additional confirmation for Einstein's theory of general relativity, which predicts how the lensing signal depends on redshift," adds co-investigator Martin Kilbinger from the Institut d'Astrophysique de Paris and the Excellence Cluster Universe.

The large number of galaxies included in this study, along with information on their redshifts is leading to a clearer map of how, exactly, part of the Universe is laid out; it helps us see its galactic inhabitants and how they are distributed. "With more accurate information about the distances to the galaxies, we can measure the distribution of the matter between them and us more accurately," notes co-investigator Jan Hartlap from the University of Bonn. "Before, most of the studies were done in 2D, like taking a chest X-ray. Our study is more like a 3D reconstruction of the skeleton from a CT scan. On top of that, we are able to watch the skeleton of dark matter mature from the Universe's youth to the present," comments William High from Harvard University, another co-author.

The astronomers specifically chose the COSMOS survey because it is thought to be a representative sample of the Universe. With thorough studies such as the one led by Schrabback, astronomers will one day be able to apply their technique to wider areas of the sky, forming a clearer picture of what is truly out there.


Notes:

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

[1] In astronomy, the redshift denotes the fraction by which the lines in the spectrum of an object are shifted towards longer wavelengths due to the expansion of the Universe. The observed redshift of a remote galaxy provides an estimate of its distance. In this study the researchers used redshift information computed by the COSMOS team using data from the SUBARU, CFHT, UKIRT, Spitzer, GALEX, NOAO, VLT, and Keck telescopes.

[2] Weak gravitational lensing: The phenomenon of gravitational lensing is the warping of spacetime by the gravitational field of a concentration of matter, such as a galaxy cluster. When light rays from distant background galaxies pass this matter concentration, their path is bent and the galaxy images are distorted. In the case of weak lensing, these distortions are small, and must be measured statistically. This analysis provides a direct estimate for the strength of the gravitational field, and therefore the mass of the matter concentration. When determining precise shapes of galaxies, astronomers have to deal with three main factors: the intrinsic shape of the galaxy (which is unknown), the gravitational lensing effect they want to measure, and systematic effects caused by the telescope and camera, as well as the atmosphere, in case of ground-based observations.

Image credit: NASA, ESA, P. Simon (University of Bonn) and T. Schrabback (Leiden Observatory)

3D Map of Dark Matter in the Universe

This three-dimensional map offers a first look at the web-like large-scale distribution of dark matter, an invisible form of matter that accounts for most of the Universe's mass.

The map reveals a loose network of dark matter filaments, gradually collapsing under the relentless pull of gravity, and growing clumpier over time.

The three axes of the box correspond to sky position (in right ascension and declination), and distance from the Earth increasing from left to right (as measured by cosmological redshift). Note how the clumping of the dark matter becomes more pronounced, moving right to left across the volume map, from the early Universe to the more recent Universe.

Credit: NASA, ESA and R. Massey (California Institute of Technology)

NASA Mission "Movie" Posters

NASA, through its Space Flight Awareness division, is now making cute posters and images for its space shuttle missions and expeditions to the International Space Station (ISS). Many of the posters have a movie poster-quality to them, some more blatantly obvious than others. :) As you can see, the above image for the STS-124 mission, which flew to the ISS in May-June 2008, is patterned after the Harry Potter movie posters. My only complaint about the images available from the website is that the majority of downloads come in the form of PDF files; I prefer jpg images myself.

Check it out!

New Planck Images Reveal Large-Scale Structure in Milky Way

Planck's ability to measure the temperature of the coldest dust particles will provide an important indicator of the physical processes at play in the interstellar medium, and in regions of star formation.

The image above covers a portion of the sky about 55 degrees in total extent. It is a three-color combination constructed from Planck's two highest frequency channels (557 and 857 GHz, corresponding to wavelengths of 540 and 350 micrometers), and an image at the shorter wavelength of 100 micrometers obtained with the Infrared Astronomical Satellite (IRAS). This combination effectively traces the dust: reddish tones correspond to temperatures as cold as 12 degrees above absolute zero, and whitish tones to significantly warmer ones (of order a few tens of degrees) in regions where massive stars are currently forming. Overall, the image shows local dust structures within 500 light years of the Sun.

New images from ESA's Planck mission reveal details of the structure of the coldest regions in our Galaxy. Filamentary clouds predominate, connecting the largest to the smallest scales in the Milky Way. These images are a scientific by-product of a mission which will ultimately provide the sharpest picture ever of the early Universe.

ESA's Planck microwave observatory – the first European mission designed to study the Cosmic Microwave Background (CMB) - has begun the second of four sky surveys, which will ultimately provide the most detailed information yet about the size, mass, age, geometry, composition and fate of the Universe. Although the primary goal of Planck is to map the CMB, by surveying the entire sky with an unprecedented combination of frequency coverage, angular resolution, and sensitivity, Planck will also provide valuable data for a broad range of studies in astrophysics. This is clearly demonstrated by new Planck images, published on March 17, 2010, which trace cold dust in our Galaxy and reveal the large-scale structure of the interstellar medium filling the Milky Way.

The images are a scientific 'by-product' of the data analysis that is currently underway, which aims to produce the highest-sensitivity (a few parts per million), highest-angular resolution (5 arcminutes) maps of the CMB. Part of the analysis process involves peeling away the foreground emission arising from a number of 'contaminants' - namely: the cosmological dipole (a signal due to our motion relative to the microwave background), and the radiation from gas and dust in the Milky Way and in distant galaxies - to reveal the underlying map of the CMB. In the process, a series of scientifically valuable maps of this foreground emission is obtained. The maps will be constructed from images like these first Planck snapshots.

Pinpointing the location of stellar formation:
One of the key characteristics of Planck is its ability to measure the temperature of the coldest dust particles. Temperature is an important physical indicator as it reflects the balance of energies in the interstellar medium, and changes significantly from place to place, tracing the evolution of the star formation process.

Among the astrophysics-related investigations to be undertaken with Planck is a program which aims to locate the coldest dusty clumps in the Galaxy, areas where star formation is about to occur. The above image demonstrates how Planck traces this cold dust: reddish tones correspond to temperatures as cold as 12 degrees above absolute zero, and whitish tones to much warmer ones (of order a few tens of degrees) in regions where massive stars are currently forming. Planck excels at detecting these dusty clumps across the whole sky and contributes the crucial information required to measure accurately the temperature of dust at these large scales. By combining data from Planck with data from other satellites, such as Herschel or NASA's Spitzer Space Telescope (both of which probe the very small scales where star formation occurs), and IRAS (which has mapped the whole sky at shorter wavelengths) astronomers will be able to study the formation of stars across the entire Milky Way.

Filamentary structures permeate the cosmos:
The space between stars is not empty but rather is filled with clouds of dust and gas - intimately mixed together - known as the 'interstellar medium'.

Filamentary structures are apparent at large-scales (as shown in this Planck image, on the right) and small-scales (as seen on the left, a Herschel image of a region in Aquila) in the Milky Way.

The large clouds seen in this second Planck image (above, on the right), which covers a region of about 55 degrees across, show the filamentary structure of the interstellar medium in the solar neighborhood (within about 150 pc, or 500 light years from the Sun). The local filaments are connected to the Milky Way, the horizontal feature at the bottom of the image, where the emission is coming from much larger distances across the disc of our Galaxy.

The image on the left shows a typical 'stellar nursery' (about 3 degrees across) in the Aquila constellation, as recently imaged by the Herschel Space Observatory. The filamentary structures seen at the smallest scales by Herschel are strikingly similar in appearance to those seen at the largest scales by Planck.

The richness of structure that is observed, and the way in which small and large scales are interconnected, provide important clues to the physical mechanisms underpinning the formation of stars and of galaxies. This example illustrates the synergy between Herschel and Planck; together these missions are imaging both the large-scale and the small-scale structure of our Galaxy.

Editor's notes:
Planck maps the sky in nine frequencies using two state-of-the-art instruments, designed to produce high-sensitivity, multi-frequency measurements of the diffuse sky radiation: the High Frequency Instrument (HFI) includes the frequency bands 100 – 857 GHz, and the Low Frequency Instrument (LFI) includes the frequency bands 30-70 GHz.

The first Planck all-sky survey began in August 2009 and is 98% complete (as of mid-March 2010). Because of the way Planck surveys the sky, the last bit of the first scan will be completed by late-May 2010. Planck will gather data until the end of 2012, during which time it will complete four sky scans. A first batch of astronomy data, called the Early Release Compact Source Catalogue, is scheduled for release in January 2011. To arrive at the main cosmology results will require about two years of data processing and analysis. The first set of processed data will be made available to the worldwide scientific community towards the end of 2012.

Photo credits:
Top photo: ESA, HFI Consortium, IRAS
Bottom photo (left): ESA and the SPIRE & PACS consortia, P. André (CEA Saclay) for the Gould's Belt Key Programme Consortium
Bottom photo (right): ESA, HFI Consortium

ESA: Bully Galaxy Rules the Neighborhood

In general, galaxies can be thought of as "social" - hanging out in groups and frequently interacting. However, this recent NASA/ESA Hubble Space Telescope image highlights how some galaxies appear to be hungry loners. These cosmic oddities have set astronomers on the "case of the missing neighbor galaxies".

Located about 500 million light-years from Earth, ESO 306-17, is a large, bright elliptical galaxy in the southern sky of a type known as a fossil group. Astronomers use this term to emphasize the isolated nature of these galaxies. However, are they like fossils - the last remnants of a once active community - or is it more sinister than that? Did ESO 306-17 gobble up its next-door neighbors?

Gravity brings galaxies together and bigger ones swallow smaller ones. There is evidence that our own Milky Way galaxy has "snacked" on numerous smaller galaxies that strayed too close. ESO 306-17 and other fossil groups may be the most extreme examples of galaxy cannibalism, ravenous systems that don't stop until they've devoured all of their neighbors.

In this image, taken by the Advanced Camera for Surveys aboard Hubble in November 2008, it appears that ESO 306-17 is surrounded by other galaxies, but the bright galaxies at bottom left are thought to be in the foreground, not at the same distance in the sky. In reality, ESO 306-17 lies fairly abandoned in an enormous sea of dark matter and hot gas [1]. When zooming in closely on ESO 306-17, one can see faint clusters of stars through the bright shine of the galaxy's large halo. These are globular clusters - tightly bound groups of stars that can often fend off cannibalism from larger, "bully" galaxies. Studying these surrounding clusters will prove helpful to astronomers in their pursuit to put the pieces of ESO 306-17's history together.

Researchers are also using this image to search for nearby ultra-compact dwarf galaxies. Ultra-compact dwarfs are mini versions of dwarf galaxies that have been left with only their core due to interaction with larger, more powerful galaxies. Most ultra-compact dwarfs discovered to date are located near giant elliptical galaxies in large clusters of galaxies, so it will be interesting to see if researchers find similar objects in fossil groups.

Notes:
[1] Studies conducted by both ESA's XMM-Newton mission and NASA's Chandra X-ray Observatory have confirmed the existence of hot gas surrounding ESO 306-17.

For more information, see also A Giant Among Galaxies?

Photo Credit: NASA, ESA and Michael West (European Southern Observatory, Chile)

Tycho Crater by LRO

Tycho Crater is an one of the most prominent craters on the moon. It appears as a bright spot in the southern highlands with rays of bright material that stretch across much of the nearside. Its prominence is not due to its size: at 85 km in diameter, it's just one among thousands of this size or larger. What really makes Tycho stand out is its relative youth. It formed recently enough that its beautiful rays, material ejected during the impact event, are still visible as bright streaks. All craters start out looking like this after they form, but their rays gradually fade away as they sit on the surface, exposed to the space environment which over time darkens them until they fade into the background.

How old is Tycho? Because the impact event scattered material to such great distances, it's thought that some of the samples at the Apollo 17 landing site originated at the Tycho impact site. These samples are impact melt glass, and radiometric age dating tells us that they formed 108 million years ago. So if these samples are truly from Tycho, the crater formed 108 million years ago as well. This may still seem old, but compared to the 3.9 billion-year age for many large lunar craters, Tycho is the new kid on the block. Directly sampling material from within the crater would help us learn more about not just when Tycho formed, but the ages of terrains on other planets throughout the solar system.

...

Tycho is also of great scientific interest because it is so well preserved, it is a great place to study the mechanics of how an impact crater forms. ... The peak is thought to be material that has rebounded back up after being compressed in the impact, and though it's a peak now, it originated at greater depth than any other portion of the crater. The floor of the crater is covered in impact melt, rocks that were heated to such high temperatures during the impact event that they turned to liquid, and flowed across the floor. In [this] image, impact melt flowed downhill and pooled, where it cooled.

Photo Credit: NASA/Goddard/Arizona State University

Milky Way Transit Authority

Samuel Arbesman, a postdoctoral sociologist at Harvard University, has created a semi-whimsical Milky Way Transit Authority map that's rather interesting. Inspired by Carl Sagan's novel, Contact, Arbesman has treated the various arms and spurs of the Milky Way in the manner of a subway map, complete with various stops and transfer stations. As Arbesman wrote:

This map is an attempt to approach our galaxy with a bit more familiarity than usual and get people thinking about long-term possibilities in outer space. Hopefully it can provide as a useful shorthand for our place in the Milky Way, the 'important' sights, and make inconceivable distances a bit less daunting. And while convenient interstellar travel is nothing more than a murky dream, and might always be that way, there is power in creating tools for beginning to wrap our minds around the interconnections of our galactic neighborhood.

I have attempted to actually make this map as accurate as possible, where each line corresponds to an arm of our galaxy, and the stations are actual places in their proper locations.

A larger PDF version of the map can be found here.

Experimental Rocket Ares I-X Lifts Off

JKCS041: Galaxy Cluster Smashes Distance Record

Visible Light (Very Large Telescope (VLT)):


XRays (Chandra):


Composite:


Photo Credits: X-ray: NASA/CXC/INAF/S.Andreon et al; Optical: DSS; ESO/VLT

This image contains X-rays from NASA's Chandra X-ray Observatory, optical data from the Very Large Telescope (VLT) and optical and infrared data from the Digitized Sky Survey. This record-breaking object, known as JKCS041, is observed as it was when the Universe was just one quarter of its current age. X-rays from Chandra are displayed here as the diffuse blue region, while the individual galaxies in the cluster are seen in white in the VLT's optical data, embedded in the X-ray emission.

JKCS041 was originally detected in 2006 with infrared observations from the United Kingdom Infrared Telescope (UKIRT). The distance to the cluster was then determined from optical and infrared observations from UKIRT, the Canada-France-Hawaii telescope in Hawaii and NASA's Spitzer Space Telescope. However, scientists were not sure if it was a true galaxy cluster, rather than one that has been caught in the act of forming. The shape and extent of the X-ray emission in the Chandra data, however, provided the definitive evidence that showed that JKCS041 was, indeed, a galaxy cluster. The Chandra data also allowed scientists to rule out other possible explanations for the data, including a group of galaxies, or a filament of galaxies seen along the line of sight.

Galaxy clusters are the largest gravitationally-bound objects in the Universe. Scientists have calculated when they should start assembling in the early Universe, and JKCS041, at a distance of some 10.2 billion light years, is on the early edge of that epoch. Follow-on observations of JKCS041 will provide scientists with an opportunity to find important information about how the Universe evolved at this crucial stage.

Four Exoplanets Seen

An interesting day in astronomy. The Minister of Space Exploration is pleased to say that two articles were recently published, announcing the discovery of four exoplanets around two stars. The announcement of exoplanets, in and of itself, isn't terribly newsworthy; after all, over 300 have been discovered so far. What make these four stand out is that all of them have been observed visually; that's newsworthy.

In the first article, published by Science, a star 128 light years away, designated HR 8799 and located in the constellation of Pegasus, was found to have three exoplanets orbiting it (labeled b, c and d in the photograph). The planets appear to be between five to ten times the mass of Jupiter, with the closest planet being the smallest and the furthest planet being the largest, somewhat like our solar system. The planets were imaged in infrared radiation and are still glowing with the original heat from their creation roughly 60 million years ago. (The Earth, by contrast, is 4.5 billion years old.)

The other exoplanet recently discovered orbits Fomalhaut, a star only 25 light years away from Earth, located in the constellation Piscis Australis, or the "Southern Fish." NASA reports:

In 2004, the coronagraph in the High Resolution Camera on Hubble's Advanced Camera for Surveys produced the first-ever resolved visible-light image of the region around Fomalhaut. (Note: A coronagraph is a device that can block the bright light of a central star to reveal faint objects around it.) It clearly showed a ring of protoplanetary debris approximately 21.5 billion miles across and having a sharp inner edge.

This large debris disk is similar to the Kuiper Belt, which encircles the solar system and contains a range of icy bodies from dust grains to objects the size of dwarf planets, such as Pluto.

Hubble astronomer Paul Kalas, of the University of California at Berkeley, and team members proposed in 2005 that the ring was being gravitationally modified or "shepherded" by a planet lying between the star and the ring's inner edge.

Now, Hubble has actually photographed a point source of light lying 1.8 billion miles inside the ring's inner edge.

...

Observations taken 21 months apart by Hubble's Advanced Camera for Surveys' coronagraph show that the object is moving along a path around the star, and is therefore gravitationally bound to it. The planet is 10.7 billion miles from the star, or about 10 times the distance of the planet Saturn from our sun.

The planet is brighter than expected for an object of three Jupiter masses. One possibility is that it has a Saturn-like ring of ice and dust reflecting starlight. The ring might eventually coalesce to form moons. The ring's estimated size is comparable to the region around Jupiter and its four largest orbiting satellites.

Kalas and his team first used Hubble to photograph Fomalhaut in 2004, and made the unexpected discovery of its debris disk. At the time they noted a few bright sources in the image as planet candidates. A follow-up image in 2006 showed that one of the objects had changed position since the 2004 exposure. The amount of displacement between the two exposures corresponds to an 872-year-long orbit as calculated from Kepler's laws of planetary motion.

To give an idea of how large an 872-year orbit is, the dwarf planet Pluto orbits the sun once every 248 years (about 28% of the time Fomalhaut b takes); the dwarf planet Eris orbits the sun once every 557 years (about 64% of Fomalhaut b's orbit).

Of course, none of these four exoplanets may actually qualify as being the first seen visually; the Minister reported on a possible exoplanet being seen in mid-September.

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One other article of note. In an article on the evolution of rocks and minerals, The Economist notes:

Understanding just how dramatically life shapes minerals will play an important role in the exploration of the universe, says Dr Hazen. Knowing which minerals form at different stages of a planet’s evolution, and which depend upon life to be present, are crucial to understanding the mineralogy of other planets and moons.

With NASA’s Messenger probe now going into orbit around Mercury, Dr Hazen predicts that it will find only 300 or so minerals on the planet. If there are 500-1,000 detected, then it will suggest that there is a lot more to Mercury than anyone originally thought. And if minerals that depend upon life for their formation show up, then researchers will be flummoxed. The same is true for Mars and other planets—including the exoplanets that have been known about but which have just been seen for the first time orbiting stars outside the Solar System. Dr Hazen argues that considering minerals in evolutionary terms is a powerful way to help identify how far a planet has developed geologically. Moreover it can tell you whether life was present at some point—and even whether it is present now.

Photo Credits: Of the HR 8799 system, The Economist; of the Fomalhaut system, NASA, ESA, P. Kalas, J. Graham, E. Chiang, E. Kite (Univ. California, Berkeley), M. Clampin (NASA/Goddard), M. Fitzgerald (Lawrence Livermore NL), K. Stapelfeldt, J. Krist (NASA/JPL), courtesy of APOD

MESSENGER's Second Flyby of Mercury

Photo credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Yesterday [6 October 2008], at 4:40 am EDT, MESSENGER successfully completed its second flyby of Mercury. ... The spectacular image shown here is one of the first to be returned and shows a WAC [Wide Angle Camera] image of the departing planet taken about 90 minutes after the spacecraft’s closest approach to Mercury. The bright crater just south of the center of the image is Kuiper, identified on images from the Mariner 10 mission in the 1970s. For most of the terrain east of Kuiper, toward the limb (edge) of the planet, the departing images are the first spacecraft views of that portion of Mercury’s surface. A striking characteristic of this newly imaged area is the large pattern of rays that extend from the northern region of Mercury to regions south of Kuiper. This extensive ray system appears to emanate from a relatively young crater newly imaged by MESSENGER, providing a view of the planet distinctly unique from that obtained during MESSENGER’s first flyby. This young, extensively rayed crater, along with the prominent rayed crater to the southeast of Kuiper, near the limb of the planet, were both seen in Earth-based radar images of Mercury but not previously imaged by spacecraft. ...

Image of a Possible Exoplanet

Photo credit: Gemini Observatory

There's a very interesting image of a possible exoplanet around a sun-like star in the constellation Scorpius. This is noteworthy because no other exoplanet has ever been observed directly near such a bright star. Usually the starlight is so brilliant - and the planet(s) so close to the star - that the planet cannot be observed directly. Instead, exoplanets are normally detected either by the gravitational pull they exert on their star or they orbit very dim brown dwarf stars that don't hide the reflected light from the planet in their own brilliance.

Whether or not the planet in the photo is indeed gravitationally tied to the star in the photo can't be determined for another two years. This is due to the fact that the exoplanet is so far away from its star: 330 AU (astronomical units; the distance from the earth to the sun is 1 AU). This is really distant! To compare it against the known dwarf planets orbiting our sun, the only one with a larger orbit is Sedna, which has an average distance from our sun of 486 AU.

Three University of Toronto scientists used the Gemini North telescope on Mauna Kea in Hawai'i to take images of the young star 1RXS J160929.1-210524 (which lies about 500 light-years from Earth) and a candidate companion of that star. They also obtained spectra to confirm the nature of the companion, which has a mass about eight times that of Jupiter, and lies roughly 330 times the Earth-Sun distance away from its star. (For comparison, the most distant planet in our solar system, Neptune, orbits the Sun at only about 30 times the Earth-Sun distance.) The parent star is similar in mass to the Sun, but is much younger.

“This is the first time we have directly seen a planetary mass object in a likely orbit around a star like our Sun,” said David Lafrenière, lead author of a paper submitted to the Astrophysical Journal Letters and also posted online. “If we confirm that this object is indeed gravitationally tied to the star, it will be a major step forward.”

Until now, the only planet-like bodies that have been directly imaged outside of the solar system are either free-floating in space (i.e. not found around a star), or orbit brown dwarfs, which are dim and make it easier to detect planetary-mass companions.

The existence of a planetary-mass companion so far from its parent star comes as a surprise, and poses a challenge to theoretical models of star and planet formation. "This discovery is yet another reminder of the truly remarkable diversity of worlds out there, and it's a strong hint that nature may have more than one mechanism for producing planetary mass companions to normal stars,” said Ray Jayawardhana, team member and author of a forthcoming book on extrasolar planets entitled Worlds Beyond.

The team’s Gemini observations took advantage of adaptive optics technology to dramatically reduce distortions caused by turbulence in Earth’s atmosphere. The near-infrared images and spectra of the suspected planetary object indicate that it is too cool to be a star or even a more massive brown dwarf, and that it is young. Taken together, such findings confirm that it is a very young, very low-mass object at roughly the same distance from Earth as the star.

Even though the likelihood of a chance alignment between such an object and a similarly young star is rather small, it will take up to two years to verify that the star and its likely planet are moving through space together. “Of course it would be premature to say that the object is definitely orbiting this star, but the evidence is extremely compelling. This will be a very intensely studied object for the next few years!” said Lafrenière.

...

Team member Marten van Kerkwijk described the group’s search method. “We targeted young stars so that any planetary mass object they hosted would not have had time to cool, and thus would still be relatively bright,” he said. “This is one reason we were able to see it at all.”

The Jupiter-sized body has an estimated temperature of about 1800 Kelvin (about 1500ºC), much hotter than our own Jupiter, which has a temperature of about 160 Kelvin (-110ºC), and its likely host is a young star of type K7 with an estimated mass of about 85% that of the Sun.

HT: Astronomy Picture of the Day

Update (4 July 2010): This exoplanet has finally been confirmed - the bright image to the above left of the star is indeed an exoplanet with a mass about eight times greater than that of Jupiter, and orbiting Star 1RXS J160929.1-210524 (or 1RXS 1609 for short) about 300 times the distance of our Earth to the Sun (i.e., 300 A.U.).  The astronomers who have investigated this exoplanet have determined that there are no other large planets (between 1-8 Jupiter masses) in this planetary system.  For more information, see First Directly Imaged Planet Confirmed Around Sun-Like Star.