- Jupiter, a Laboratory for Studying Exoplanets
- Mars Hills Hide Icy Past
- The Answer Is Blowing in the Black Hole Wind
- SBIRS Constellation Forms Under One Roof
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Posted: 19 Feb 2015 10:55 PM PST
The scientific journal Astrophysical Journal Letters is publishing a study, led by researchers at the Astrophysical Institute of the Canaries (IAC), which has been the subject of a report in the journal Nature. It the study Jupiter is presented as an ideal laboratory for research into exoplanets which are similar. Jupiter, the largest planet in the Solar System, has large satellites around it. The study has used the largest of the satellites, which is the biggest satellite in the Solar System, Ganymede, as a mirror to analyze the atmosphere of the planet. The observations were performed during an eclipse of Ganymede by Jupiter, and allowed the researchers to observe Jupiter as if it were a transiting exoplanet.
Its transmisión spectrum, observed as Ganymede began to be eclipsed, and could be observed through the atmosphere of Jupiter, shows strong extinction, reduction of the light due to clouds and to aerosols in Jupter´s atmophsere, as well as strong absorption in the characteristic bands of methane (CH4), and most surprising, ice crystals in a stratospheric layer. These results are of relevance to the modelling and the interpretation of transiting exoplanets, but they also offer a new technique to characterize the upper layers of Jupiter’s atmosphere, and to determine the abundance of water. It will also be useful in helping establish the rate of comet impact on Jupiter, and its consequences for the history of the formation of the Solar System.
During the last two decades more than 1,800 exoplanets have been discovered, 65% of them using the transit method. This entails observing a star with very accurate photometry, to detect the slight drop in the intensity of its light when a planet passes in front of it. For a small proportion of these planets, those which orbit around the brightest stars, their atmospheres can be studied using the method of transmission spectroscopy, where one measures the difference between the light emitted and the light transmitted, which gives a “fingerprint” of the composition of the atmosphere. At the present time this is the most successful technique for probing the chemical composition of the atmospheres of exoplanets.
During the transit of the planet across the front face of the star, some of the light from the star is blocked, and only a ten thousandth part passes through the thin atmospheric layer of the planet (for a planet like Jupiter, and a star like the Sun), bringing with it information about its atmospheric layers and their components.
“In order to explore the limitations of this technique” explains Pilar Montañés, a researcher at the IAC and the first author of the article “ we have applied it to study the atmosphere of Jupiter. We have measured the transmission spectrum of Jupiter, observing it as if it were an exoplanet. Our method has been to take high resolution spectra of Ganymede, (Jupiter’s third satellite out) during its passage through the shadow of the planet. In spectrum obtained when we divide the spectra observed before and during the eclipse, the signals from the Sun, from the Earth, and from Ganymede itself, (which is on a synchronous orbit around Jupiter) are eliminated.”
The study shows that the strongest absorptions are due to methane, as one would expect for Jupiter. However the observation of the extinction due to clouds and to aerosol particles is also relevant. “Our results” explains Enric Pallé, an IAC researcher and co-author of the article “support previous results in which transmission spectroscopy indicated the detection of clouds and of aerosols in “hot Jupiters”. As the eclipse progresses, out method allows us to probe the atmosphere of the planet in greater depth.
However the most interesting signal which was detected, between 1.5 and 2.0 microns, is probably due to stratospheric clouds of ice crystals. “Our models,” notes Manuel López Puertas of the Astrophysical Institute of Andalucia (IAA-CSIC), “have allowed us to determine that the column of water ice contains 1,013 particles / cm2, a much larger quantity of water than that previously measured in the vapour state. We have also detected spectral lines of sodium iodide (NaI) in Jupiter´s atmosphere, due either to the continual deposit of sodium from comets, or to a continual flux of sodium from the satellite Io”.
“This is the first time that this kind of observations has been performed from the ground, and have covered such a wide spectral range“ notes Beatriz González, another member of the team, who was also at the iAC when the study was carried out.
The observations were performed during two eclipses in 2012 using the LIRIS instrument on the William Herschel Telescope at the Roque de los Muchachos Observatory (La Palma), and the XSHOOTER instrument on the VLT (Very Large Telescope) at the Paranal Observatory of the European Southern Observatory (ESO) in Chile, in three spectral ranges: the ultraviolet, the visible, and the infrared. Similar observations had been previously obtained to obtain the transmission spectrum of the Earth using lunar eclipses, by Enric Pallé, Pilar Montañés, and their collaborators in 2009.
Credit: iaa.es
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Posted: 19 Feb 2015 02:22 PM PST
A complex network of isolated hills, ridges and small basins spanning 1400 km on Mars is thought to hide large quantities of water-ice. Phlegra Montes stretches from the Elysium volcanic region at about 30ºN and deep into the northern lowlands at about 50°N, and is a product of ancient tectonic forces. Its age is estimated to be 3.65–3.91 billion years. ESA’s Mars Express imaged the portion of Phlegra Montes seen here on 8 October 2014. It captures the southernmost tip of the range centred on 31ºN / 160ºE.
Based on radar data from NASA’s Mars Reconnaissance Orbiter combined with studies of the region’s geology from other orbiters, scientists believe that extensive glaciers covered this region several hundred million years ago.
And it is thought that ice is still there today, perhaps only 20 m below the surface.
The tilt of the planet’s polar axis is believed to have varied considerably over time, leading to significantly changing climatic conditions. This allowed the development of glaciers at what are today the mid-latitudes of Mars.
Features visible in the Phlegra Montes mountain range providing strong evidence for glacial activity include aprons of rocky debris surrounding many of the hills. Similar features are seen in glacial regions on Earth, where material has gradually slumped downhill through the presence of subsurface ice.
Additional features in the region include small valleys cutting through the hills and appearing to flow into regions of lower elevation, in particular towards the centre of the image.
The hummocky terrain provides a distinct contrast to the smooth plains that dominate the upper portion of this image. The material here is thought to be volcanic in origin, perhaps originating from the Hecates Tholus volcano in Elysium some 450 km to the west, some time after the formation of Phlegra Montes.
Upon closer inspection, ‘wrinkle ridges’ can be seen in the lava plain. These features arise from the cooling and contraction of lava owing to compressive tectonic forces following its eruption onto the surface.
This region of Phlegra Montes and its local surrounds illustrate some of the key geological processes that have worked to shape the Red Planet over time, from ancient tectonic forces, to glaciation and volcanic activity.
Credit: ESA
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Posted: 19 Feb 2015 01:01 PM PST
NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and ESA’s (European Space Agency) XMM-Newton telescope are showing that fierce winds from a supermassive black hole blow outward in all directions -- a phenomenon that had been suspected, but difficult to prove until now. This discovery has given astronomers their first opportunity to measure the strength of these ultra-fast winds and prove they are powerful enough to inhibit the host galaxy’s ability to make new stars. "We know black holes in the centers of galaxies can feed on matter, and this process can produce winds. This is thought to regulate the growth of the galaxies," said Fiona Harrison of the California Institute of Technology (Caltech) in Pasadena, California. Harrison is the principal investigator of NuSTAR and a co-author on a new paper about these results appearing in the journal Science. "Knowing the speed, shape and size of the winds, we can now figure out how powerful they are."
Supermassive black holes blast matter into their host galaxies, with X-ray-emitting winds traveling at up to one-third the speed of light. In the new study, astronomers determined PDS 456, an extremely bright black hole known as a quasar more than 2 billion light-years away, sustains winds that carry more energy every second than is emitted by more than a trillion suns.
"Now we know quasar winds significantly contribute to mass loss in a galaxy, driving out its supply of gas, which is fuel for star formation," said the study’s lead author, Emanuele Nardini of Keele University in England.
NuSTAR and XMM-Newton simultaneously observed PDS 456 on five separate occasions in 2013 and 2014. The space telescopes complement each other by observing different parts of the X-ray light spectrum: XMM-Newton views low-energy and NuSTAR views high-energy.
Previous XMM-Newton observations had identified black-hole winds blowing toward us, but could not determine whether the winds also blew in all directions. XMM-Newton had detected iron atoms, which are carried by the winds along with other matter, only directly in front of the black hole, where they block X-rays. The scientists combined higher-energy X-ray data from NuSTAR with observations from XMM-Newton. By doing this, they were able to find signatures of iron scattered from the sides, proving the winds emanate from the black hole not in a beam, but in a nearly spherical fashion.
"This is a great example of the synergy between XMM-Newton and NuSTAR,” said Norbert Schartel, XMM-Newton project scientist at ESA. “The complementarity of these two X-ray observatories is enabling us to unveil previously hidden details about the powerful side of the universe.”
With the shape and extent of the winds known, the researchers could then determine the strength of the winds and the degree to which they can inhibit the formation of new stars.
Astronomers think supermassive black holes and their home galaxies evolve together and regulate each other's growth. Evidence for this comes in part from observations of the central bulges of galaxies -- the more massive the central bulge, the larger the supermassive black hole.
This latest report demonstrates a supermassive black hole and its high-speed winds greatly affect the host galaxy. As the black hole bulks up in size, its winds push vast amounts of matter outward through the galaxy, which ultimately stops new stars from forming.
Because PDS 456 is relatively close, by cosmic standards, it is bright and can be studied in detail. This black hole gives astronomers a unique look into a distant era of our universe, around 10 billion years ago, when supermassive black holes and their raging winds were more common and possibly shaped galaxies as we see them today.
"For an astronomer, studying PDS 456 is like a paleontologist being given a living dinosaur to study," said study co-author Daniel Stern of NASA's Jet Propulsion Laboratory in Pasadena. "We are able to investigate the physics of these important systems with a level of detail not possible for those found at more typical distances, during the 'Age of Quasars.'"
NuSTAR is a Small Explorer mission led by Caltech and managed by JPL for NASA's Science Mission Directorate in Washington.
Credit: nustar.caltech.edu
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Posted: 19 Feb 2015 11:28 AM PST
Airmen from the 460th Operations Group have made history by successfully completing the first series of Space Based Infrared System (SBIRS) satellite and antenna communication on Jan. 28-30 from Block 10, the new operations floor, on Buckley Air Force Base, Colo. The communication to SBIRS satellites and ground antennas is the first step in transforming Block 10 into the new, consolodated operations floor for Defense Support Program, Highly Elliptical Orbit and Geostationary satellites. Currently, each type of satellite communication platform is in separate locations across Colorado, making it difficult to communicate efficiently as a whole. Bringing the three units together will unify the SBIRS constellation under one roof.
"The intent of Block 10 is to bring all three platforms here in one place to the Mission Control Station," said Capt. Natasha Rosario, 2nd Space Warning Squadron SBIRS satellite engineering chief.
The first SBIRS command was sent on Jan. 28 by the youngest, newest Airman in the 460th OG to the oldest satellite in orbit. Airman 1st Class Brandon Cruz, 2nd Space Warning Squadron, was the first to send commands to a DSP satellite from the Block 10 floor.
Wing and operations group leadership were at Block 10 on the 28th, waiting to see history be made, and a celebration broke out when the command came back successful.
"It was kind of fun," Rosario said. "They sent the very first one which was on DSP, and everyone clapped after the first command went out. They were like, 'yes it worked!'"
The second was done by Airman 1st Class Ali Tabbicca, 2 SWS, to the first HEO payload, the third by Senior Airman David Deadmon, 2 SWS, to the GEO payload.
There's a year and a half until all three platforms will be working on the Block 10 floor, which will then be called Mission Control Station 2, Rosario said. There will be a period of checking out the Block 10 system and software, assuring the ground software delivery can be executed flawlessly.
"We've put testing and rehearsals and practices in place to make sure that we not only check out the system, but that the people are also ready and bringing those two things together as well," Rosario said.
It will be a crawl, walk, then run progression.
Starting with live, single communication, which is what they have already begun, the 460th OG will continue testing their communication with only one satellite or antenna at a time.
The second stage, which will be communicating with two satellites or antennas at a time, will begin in the next month or two. For example, communicating with GEO and HEO simultaneously. An estimated year from now, the OG will have full communication with the entire SBIRS constellation at one time.
This advancement means a lot for the 460th OG and Team Buckley as a whole Rosario said. The squadron will almost double in size and many OG Airmen will have to undertake many hours of training to keep up with the transition to Block 10.
Airmen from the other Colorado SBIRS locations are scheduled to move to Buckley to finish the transition and unify the SBIRS constellation.
"This is a major milestone for a multi-billion dollar system toward a critical national mission in which we have been diligently working for a very long time," said Col. Michael Jackson, 460th OG commander.
Credit: afspc.af.mil
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