NEWLY IDENTIFIED GALACTIC SUPERCLUSTER IS HOME TO THE MILKY WAY
From the FMS Global News Desk of Jeanne Hambleton Embargoed: 3-Sep-2014 Source Newsroom: National Radio Astronomy Observatory Citations Nature, Sept. 4, 2014
Credit: SDvision interactive visualization software by DP at CEA/Saclay, France. A slice of the Laniakea Supercluster in the supergalactic equatorial plane — an imaginary plane containing many of the most massive clusters in this structure. The colors represent density within this slice, with red for high densities and blue for voids — areas with relatively little matter. Individual galaxies are shown as white dots. Velocity flow streams within the region gravitationally dominated by Laniakea are shown in white, while dark blue flow lines are away from the Laniakea local basin of attraction. The orange contour encloses the outer limits of these streams, a diameter of about 160 Mpc. This region contains the mass of about 100 million billion suns.
Newswise — Astronomers using the National Science Foundation’s Green Bank Telescope (GBT) — among other telescopes — have determined that our own Milky Way galaxy is part of a newly identified ginormous supercluster of galaxies, which they have dubbed “Laniakea,” which means “immense heaven” in Hawaiian.
This discovery clarifies the boundaries of our galactic neighborhood and establishes previously unrecognized linkages among various galaxy clusters in the local Universe.
“We have finally established the contours that define the supercluster of galaxies we can call home,” said lead researcher R. Brent Tully, an astronomer at the University of Hawaii at Manoa.
“This is not unlike finding out for the first time that your hometown is actually part of much larger country that borders other nations.”
The paper explaining this work is the cover story of the September 4 issue of the journal Nature.
Superclusters are among the largest structures in the known Universe. They are made up of groups, like our own Local Group, that contain dozens of galaxies, and massive clusters that contain hundreds of galaxies, all interconnected in a web of filaments. Though these structures are interconnected, they have poorly defined boundaries.
To better refine cosmic map making, the researchers are proposing a new way to evaluate these large-scale galaxy structures by examining their impact on the motions of galaxies. A galaxy between structures will be caught in a gravitational tug-of-war in which the balance of the gravitational forces from the surrounding large-scale structures determines the galaxy’s motion.
By using the GBT and other radio telescopes to map the velocities of galaxies throughout our local Universe, the team was able to define the region of space where each supercluster dominates.
“Green Bank Telescope observations have played a significant role in the research leading to this new understanding of the limits and relationships among a number of superclusters,” said Tully.
The Milky Way resides in the outskirts of one such supercluster, whose extent has for the first time been carefully mapped using these new techniques. This so-called Laniakea Supercluster is 500 million light-years in diameter and contains the mass of one hundred million billion Suns spread across 100,000 galaxies.
This study also clarifies the role of the Great Attractor, a gravitational focal point in intergalactic space that influences the motion of our Local Group of galaxies and other galaxy clusters.
Within the boundaries of the Laniakea Supercluster, galaxy motions are directed inward, in the same way that water streams follow descending paths toward a valley. The Great Attractor region is a large flat bottom gravitational valley with a sphere of attraction that extends across the Laniakea Supercluster.
The name Laniakea was suggested by Nawa‘a Napoleon, an associate professor of Hawaiian Language and chair of the Department of Languages, Linguistics, and Literature at Kapiolani Community College, a part of the University of Hawaii system. The name honors Polynesian navigators who used knowledge of the heavens to voyage across the immensity of the Pacific Ocean.
The other authors are Hélène Courtois (University Claude Bernard Lyon 1, Lyon, France), Yehuda Hoffman (Racah Institute of Physics, Hebrew University, Jerusalem), and Daniel Pomarède (Institute of Research on Fundamental Laws of the Universe, CEA/Saclay, France).
The GBT is the world’s largest fully steerable radio telescope. Its location in the National Radio Quiet Zone and the West Virginia Radio Astronomy Zone protects the incredibly sensitive telescope from unwanted radio interference.
The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.
Founded in 1967, the Institute for Astronomy at the University of Hawaii at Manoa conducts research into galaxies, cosmology, stars, planets, and the sun. Its faculty and staff are also involved in astronomy education, deep space missions, and in the development and management of the observatories on Haleakala and Maunakea. The Institute operates facilities on the islands of Oahu, Maui, and Hawaii.
SCIENTISTS’ WORK MAY LEAD TO MISSION TO FIND OUT WHAT’S INSIDE ASTEROIDS
From the FMS Global News Desk of Jeanne Hambleton Released: 2-Sep-2014
Source: University of Alabama Huntsville
Newswise — HUNTSVILLE, Ala. (Sept. 2, 2014) – Future asteroid mining operations and how we deal with an impending strike could be influenced by research on a potential NASA mission that is being done by team that includes a University of Alabama in Huntsville (UAH) scientist.
“If you identify an asteroid coming toward us, how you deal with it could depend on its density and structure,” says Dr. Richard S. Miller, a UAH physics professor.
“Likewise, if this technique pans out, you could imagine sending out a specialized telescope to determine what the densities and interior structure of various asteroids are, then decide on the basis of that information what ones to mine.”
Little is now known about asteroid interior density and composition. Are they uniform or are they what astrophysicists call differentiated bodies, having denser and less-dense areas?
“Asteroids are time capsules of the early solar system,” Dr. Miller says.
“We know about their surface properties and we can also infer the mass of some asteroids. But what we want to do is actually probe the interior of asteroids and determine information about their structure, are there interior density gradients, what is the composition – is it solid or like Swiss cheese – and do they have cores or not? Is it a pile of rubble? It turns out this structure can tell us a great deal about the conditions present during the early epochs of solar system formation and its evolution.”
To find that out, the team’s scientists will be borrowing imaging technology concepts developed for medicine and high-energy physics. They are developing a mission concept to probe asteroids using a technique similar to human computerized tomography (CT) scans. Dr. Miller is a co-investigator in a collaborative effort with the Planetary Science Institute (PSI), NASA’s Johnson Space Center, the Universities Space Research Association’s Arecibo Observatory (Arecibo/USRA) and the University of Houston to do the fundamental research and design that could lead to such a mission.
Led by principal investigator Dr. Tom Prettyman, senior scientist at PSI, the group has $500,000 in funding from the NASA Innovative Advanced Concepts (NIAC) Phase II program. The team’s two-year proposal, “Deep Mapping of Small Solar System Bodies with Galactic Cosmic Ray Secondary Particle Showers,” is one of only five projects selected for funding. Other funded collaborators include Dr. Steven Koontz, NASA Johnson Space Center; Dr. Michael Nolan, Arecibo/USRA; Dr. Lawrence Pinsky, University of Houston; and Dr. Mark Sykes, PSI.
The team proposes using ever-present cosmic rays to perform its measurements. All objects in space are constantly bombarded by these particles, which are thought to be the remnants of massive supernovas and are primarily protons. On Earth, the atmosphere breaks them up and shields us from direct hits.
“In space, on contact with dense matter like the moon’s surface or other airless planetary bodies, they interact within the first few centimeters of depth and create a shower of particles,” Dr. Miller says. Studying those interactions has provided us surface knowledge of asteroids.
“But cosmic rays also contain muons, which are particles similar to electrons, but which can go a lot farther into the asteroid, in some cases up to one kilometer.”
The idea is to position a telescope to orbit the asteroid and measure the number and trajectories of the muons passing through it.
“Muons are like an SUV,” says Dr. Miller. “Once they are moving it is not easy to knock them off their course.”
An asteroid composed of varying densities of material would return a different pattern than one with a single density, just as a CT scan differentiates between densities of structures in the body. Likewise, if an asteroid has a denser core, it will stop muons from passing through and the telescope will detect the change. That process is called muon tomography and is well understood. Developed in the 1950s, it was even used in the 1960s by Luis Alvarez to map the Pyramid of Chephren.
“What’s different about a CT scan is that instead of using cosmic rays and muons to determine densities, a CT scan uses x-rays,” Dr. Miller says.
To mature the concept, the scientists must first solve a number of fundamental challenges. They will be using computer modeling to work on:
- Detailed estimates of the particle signatures, including muons and other radiations that will be present in deep space and in the neighborhood of any asteroids;
• Doing the initial work on the muon telescope’s design and operation. There are competing ideas, and the team will evaluate a variety of performance tradeoffs;
• The development and implementation of advanced algorithms for asteroid structure reconstruction;
• Establishing the preliminary outlines of how a proposed NASA mission would be conducted, its feasibility and making predictions of the ultimate science return.
“What it has to do is detect those muons and give us a direction they are coming from,” Dr. Miller says of the telescope, but getting to that goal involves tradeoffs.
For example, the bigger the area the telescope can scan as it orbits, the less time it will take to get results encompassing an entire asteroid being studied. But the greater the telescope’s size, the more resources will be involved to launch the mission. Also, to tell where the muons are coming from, the telescope will have to be able to tell directional “up” from “down.”
Dr. Miller says he was already exploring using muons to probe asteroids when he attended a conference and found that PSI’s Dr. Prettyman was working on the same thing.
“This is a good story of how you had two independent groups who were both looking at the same idea,” Dr. Miller says, “and we have joined forces to make a stronger project.”
INTENSE EXERCISE DURING LONG SPACE FLIGHTS HELPS ASTRONAUTS PROTECT AEROBIC CAPACITY
From the FMS Global News Desk of Jeanne Hambleton Released: 29-Aug-2014
Source: American Physiological Society (APS)
Newswise — Bethesda, Md. (August 29, 2014) — Most people do not think much about their aerobic capacity while at work. But for astronauts carrying out missions on the International Space Station (ISS), maintaining their cardiovascular stamina during long space flights is part of the job. They must be prepared to perform physically demanding tasks or emergency maneuvers at any time during flights that can last between three and six months in a weightless environment.
In an effort to protect their aerobic capacity and prepare their bodies, astronauts routinely perform in-flight cardiovascular and strength exercises. But the effect of exercise on astronauts traveling to the ISS was not known because aerobic capacity (V̇O2peak) had only been studied in shorter trips, not during and after longer space flights.
To understand whether the routinely prescribed exercise was effectively maintaining V̇O2peak, researchers Alan D. Moore Jr., et al., with the National Aeronautics and Space Administration (NASA) Human Research Program followed 14 astronauts (nine men and five women) who traveled on space flights between 91 and 192 days. On average, the subjects exercised 30 minutes a day on five to six days each week at an average intensity of 73% of peak heart rate. The research team measured V̇O2peak at approximately nine months and three months before launch; on day 15 of the flight; every subsequent 30 flight days; and day one, 10 and 30 following re-entry to Earth.
The research team observed a ~17% overall reduction in V̇O2peak by flight day 15 across the study sample. While some astronauts experienced a significant decline in V̇O2peak (a dip that rebounded later in the space flight), other astronauts did not experience any substantial change in V̇O2peak. Interestingly, the astronauts with the highest V̇O2peak experienced the greatest reduction in capacity, but according to the authors, “this finding should not be interpreted that a high preflight aerobic capacity is undesirable. Although the astronauts with high capacities tended to lose more, they typically remained at higher levels than crew who started at lower levels.
“These results provide evidence that, although many astronauts experience a decline in V̇O2peak during ISS missions, use of the aerobic exercise hardware aboard the ISS combined with exercise prescriptions of sufficient exercise intensity can be used to effectively prevent decline in aerobic capacity,” the researchers wrote.
The article “Peak exercise oxygen uptake during and following long-duration spaceflight” is published in the Journal of Applied Physiology. It is highlighted as one of this month’s “best of the best” as part of the American Physiological Society’s APSselect program.
Physiology is the study of how molecules, cells, tissues and organs function in health and disease. Established in 1887, the American Physiological Society (APS) was the first US society in the biomedical sciences field. The Society represents more than 11,000 members and publishes 14 peer-reviewed journals with a worldwide readership.
Back tomorrow Jeanne