Dr. Barry Welsh gives a talk on ExoComets at the SETI Institute
Present technology does not enable us to view images of these kilometer-sized infalling bodies, but the evaporation of gaseous products liberated from exocomets that occurs close to a star can potentially cause small disruptions in the ambient circumstellar disk plasma. For circumstellar disks that are viewed “edge-on” this evaporating material may be directly observed through transient (night-to-night and hour-to-hour) gas absorption features seen at rapidly changing velocities. Using high resolution spectrographs mounted to large aperture ground-based telescopes, we have discovered 15 young stars that harbor swarms of exocomets. In this lecture we briefly describe the physical attributes of comets in our own solar system and the instrumental observing techniques to detect the presence of evaporating exocomets present around stars with ages in the 10 – 100 Myr range. We note that this work has particular relevance to the dramatic fluctuations in the flux recorded towards “Tabby’s star” by the NASA Kepler Mission, that may be explained through the piling up of swarms of exocomets in front of the central star.
This image from NASA’s Chandra X-ray Observatory shows spiral galaxy NGC 7331, center, in a three-color X-ray image. Red, green and blue colors are used for low, medium and high-energy X-rays, respectively. An unusual supernova called SN 2014C has been spotted in this galaxy, indicated by the box.
Credits: NASA/CXC/CIERA/R.Margutti et al
In the new study, NASA’s NuSTAR (Nuclear Spectroscopic Telescope Array) satellite, with its unique ability to observe radiation in the hard X-ray energy range—the highest-energy X-rays—allowed scientists to watch how the temperature of electrons accelerated by the supernova shock changed over time. They used this measurement to estimate how fast the supernova expanded and how much material is in the external shell.
To create this shell, SN 2014C did something truly mysterious: it threw off a lot of material—mostly hydrogen, but also heavier elements—decades to centuries before exploding. In fact, the star ejected the equivalent of the mass of the sun. Normally, stars do not throw off material so late in their life.
“Expelling this material late in life is likely a way that stars give elements, which they produce during their lifetimes, back to their environment,” said Margutti, a member of Northwestern’s Center for Interdisciplinary Exploration and Research in Astrophysics.
The complete article thanks to Elizabeth Landau, Jet Propulsion Lab is here.
Monster black holes sometimes lurk behind gas and dust, hiding from the gaze of most telescopes. But they give themselves away when material they feed on emits high-energy X-rays that NASA’s NuSTAR (Nuclear Spectroscopic Telescope Array) mission can detect. That’s how NuSTAR recently identified two gas-enshrouded supermassive black holes, located at the centers of nearby galaxies.
“These black holes are relatively close to the Milky Way, but they have remained hidden from us until now,” said Ady Annuar, a graduate student at Durham University in the United Kingdom, who presented the results at the American Astronomical Society meeting in Grapevine, Texas. “They’re like monsters hiding under your bed.”
Both of these black holes are the central engines of what astronomers call “active galactic nuclei,” a class of extremely bright objects that includes quasars and blazars. Depending on how these galactic nuclei are oriented and what sort of material surrounds them, they appear very different when examined with telescopes.
The complete article here, thanks to http://nustar.ipac.caltech.edu
NASA’s ICON and GOLD missions will take complementary observations of Earth’s ionosphere and upper atmosphere. NASA image.
Scientists at UC Berkeley’s Space Sciences Laboratory are preparing for the 2017 launch of an Earth-orbiting satellite to discover how storms in the atmosphere affect storms in the ionosphere.
The ionosphere is the edge of space where the sun ionizes the air in Earth’s atmosphere to create constantly shifting streams and sheets of charged particles.
The NASA-funded satellite, called the Ionospheric Connection Explorer, or ICON, will complement observations from a sister satellite also scheduled for launch in 2017: the Global Observations of the Limb and Disk, or GOLD. GOLD is being led by the University of Central Florida, though UC Berkeley space scientist Scott England works on both missions.
The complete article by Robert Sanders of Berkeley News is here:
Recently at the annual AGU, American Geophysical Union, meetings in San Francisco, Dr. Thomas Immel Discusses the ICON mission and NRL, Naval Research Labs, MIGHTI instrument. See the video:
The artwork is based on an image of the Pinwheel galaxy (Messier 101) taken by NASA’s Hubble Space Telescope
Supermassive black holes at the cores of galaxies blast radiation and ultra-fast winds outward, as illustrated in this artist’s conception. New data from NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR) and the European Space Agency’s (ESA’s) XMM-Newton telescopes show that these winds, which contain gases of highly ionized atoms, blow in a nearly spherical fashion, emanating in every direction, as shown in the artwork. The findings rule out the possibility that the winds blow in narrow beams.
With the shape and extent of the winds known, the researchers were able to determine the winds’ strength. The high-speed winds are powerful enough to shut down star formation throughout a galaxy.
The artwork is based on an image of the Pinwheel galaxy (Messier 101) taken by NASA’s Hubble Space Telescope.
NuSTAR’s mission operations center is at UC Berkeley, Space Sciences Lab, with the ASI providing its equatorial ground station located at Malindi, Kenya. The mission’s outreach program is based at Sonoma State University, Rohnert Park, California. NASA’s Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.
For more information, visit http://www.nasa.gov/nustar and http://www.nustar.caltech.edu/.
Launched ten years ago, on Oct. 25, 2006, the twin spacecraft of NASA’s STEREO mission – short for Solar and Terrestrial Relations Observatory – have given us unprecedented views of the sun, including the first-ever simultaneous view of the entire star at once. This kind of comprehensive data is key to understanding how the sun erupts with things like coronal mass ejections and energetic particles, as well as how those events move through space, sometimes impacting Earth and other worlds. Ten years ago, the twin STEREO spacecraft joined a fleet of NASA spacecraft monitoring the sun and its influence on Earth and space – and they provided a new and unique perspective.
The two STEREO observatories, called STEREO-A and STEREO-B – for Ahead and Behind, respectively – were sent out from Earth in opposite directions. Using gravitational assists from both the moon and Earth, the STEREO spacecraft were accelerated to Earth-escape velocities. STEREO-A was inserted into an orbit slightly smaller, and therefore faster, than Earth’s. For STEREO-B, the reverse happened: It was nudged into an orbit slightly larger than Earth’s so that it traveled around the sun more slowly, falling increasingly behind the Earth. As the spacecraft slowly fanned out away from the centerline between Earth and the sun – where every other sun-watching spacecraft is located – they revealed more and more new information about our closest star.
For STEREO’s 10th anniversary, Deputy Project Scientist Terry Kucera gives an overview of the missions top 5 success stories.
Credit: NASA’s Goddard Space flight Center/Genna Duberstein
Music credit: Life Choices by Eric Chevalier
Read more: http://www.nasa.gov/feature/goddard/2…
This video is public domain and along with other supporting visualizations can be downloaded from the Scientific Visualization Studio at: http://svs.gsfc.nasa.gov/12381
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A new online science game allows the general public to directly contribute to Alzheimer’s disease research and help scientists search for a cure.
A screenshot of the Stall Catchers game.
The game, called Stall Catchers, was developed by the Human Computation Institute, in collaboration with UC Berkeley and other institutions, as part of the EyesOnALZ citizen science project. Stall Catchers will allow participants to look at movies of real blood vessels in mouse brains and search for clogged capillaries, or stalls, where blood is no longer flowing, Previous research suggests that capillary stalls could be a key culprit in Alzheimer’s disease.
The citizen science approach for Stall Catchers was developed by physicist Andrew Westphal, a senior fellow at the UC Berkeley Space Sciences Laboratory. The approach was first used in a project called Stardust@home, developed here at Space Sciences Lab, in which more than 30,000 amateur scientists have carried out more than 100 million searches to identify interstellar dust in collectors returned by the NASA Stardust comet sampling mission. Stardust@home led to the discovery of seven particles of likely interstellar origin, reported in the journal Science in 2014.
You can read more about Stall Catchers in a Berkeley News article.
Our planet is nestled in the center of two doughnut-shaped regions of powerful, dynamic radiation: the Van Allen belts, where high-energy particles are trapped by Earth’s magnetic field. Depending on incoming radiation from the sun, they can gain energetic particles. On the other hand, the belts can lose energized particles too.
This video illustrates the complexity of Earth’s magnetic environment, from the radiation belts encircling Earth to the magnetic field lines, depicted as blue ribbons, extending far out into space. During a drop-out, ultra-relativistic electrons stream down along powerful electromagnetic waves, as if they are raining into the atmosphere.
Credits: NASA Goddard/Joy Ng/Martin Rother/GFZ-Potsdam
We are familiar with rapid changes in weather, and the radiation belts can experience these too – particles can be depleted by a thousand-fold in mere hours. These dramatic loss events are called drop-outs, and they can happen when intense bouts of solar radiation disturb Earth’s magnetic environment. There have been many theories on how this happens, but scientists have not had the data to pinpoint which one is correct.
However, on Jan. 17, 2013, NASA’s Van Allen Probes were in just the right position to watch a drop-out in progress and resolve a long-standing question as to how the lower region of the belts close to Earth loses high-energy electrons – known as ultra-relativistic electrons for their near-light speeds. During a drop-out, a certain class of powerful electromagnetic waves in the radiation belts can scatter ultra-relativistic electrons. The electrons stream down along these waves, as if they are raining into the atmosphere. A team led by Yuri Shprits of University of California in Los Angeles published a paper summarizing these findings in Nature Communications on Sept. 28, 2016.
Such information helps illustrate the complexity of Earth’s magnetic surroundings. Understanding changes within the belts is crucial for protecting the satellites and astronauts travelling through this sometimes harsh space environment.