New observations with ESO’s Very Large Telescope have revealed that the giant elliptical galaxy Messier 87 has swallowed an entire medium-sized galaxy over the last billion years. For the first time a team of astronomers has been able to track the motions of 300 glowing planetary nebulae to find clear evidence of this event and also found evidence of excess light coming from the remains of the totally disrupted victim.
Astronomers expect that galaxies grow by swallowing smaller galaxies. But the evidence is usually not easy to see — just as the remains of the water thrown from a glass into a pond will quickly merge with the pond water, the stars in the infalling galaxy merge in with the very similar stars of the bigger galaxy leaving no trace.
But now a team of astronomers led by PhD student Alessia Longobardi at the Max-Planck-Institut für extraterrestrische Physik, Garching, Germany has applied a clever observational trick to clearly show that the nearby giant elliptical galaxy Messier 87 merged with a smaller spiral galaxy in the last billion years.
“This result shows directly that large, luminous structures in the Universe are still growing in a substantial way — galaxies are not finished yet!” says Alessia Longobardi. “A large sector of Messier 87’s outer halo now appears twice as bright as it would if the collision had not taken place.”
Messier 87 lies at the centre of the Virgo Cluster of galaxies. It is a vast ball of stars with a total mass more than a million million times that of the Sun, lying about 50 million light-years away.
Rather than try to look at all the stars in Messier 87 — there are literally billions and they are too faint and numerous be studied individually — the team looked at planetary nebulae, the glowing shells around ageing stars . Because these objects shine very brightly in a specific hue of aquamarine green, they can be distinguished from the surrounding stars. Careful observation of the light from the nebulae using a powerful spectrograph can also reveal their motions .
Just as the water from a glass is not visible once thrown into the pond — but may have caused ripples and other disturbances that can be seen if there are particles of mud in the water — the motions of the planetary nebulae, measured using the FLAMES spectrograph on the Very Large Telescope, provide clues to the past merger.
“We are witnessing a single recent accretion event where a medium-sized galaxy fell through the centre of Messier 87, and as a consequence of the enormous gravitational tidal forces, its stars are now scattered over a region that is 100 times larger than the original galaxy!” adds Ortwin Gerhard, head of the dynamics group at the Max-Planck-Institut für extraterrestrische Physik, Garching, Germany, and a co-author of the new study.
The team also looked very carefully at the light distribution in the outer parts of Messier 87 and found evidence of extra light coming from the stars in the galaxy that had been pulled in and disrupted. These observations have also shown that the disrupted galaxy has added younger, bluer stars to Messier 87, and so it was probably a star-forming spiral galaxy before its merger.
“It is very exciting to be able to identify stars that have been scattered around hundreds of thousands of light-years in the halo of this galaxy — but still to be able to see from their velocities that they belong to a common structure. The green planetary nebulae are the needles in a haystack of golden stars. But these rare needles hold the clues to what happened to the stars,” concludes co-author Magda Arnaboldi (ESO, Garching, Germany).
Among the highlights of Ford’s collection was a pouch that held some of Apollo 11 moonwalker Buzz Aldrin’s personal mementos as they were flown to lunar orbit and back. The Personal Preference Kit (PPK) bag had already attracted bids topping $25,000 when absentee pre-bidding closed on Wednesday.
Other exceptional artifacts include a life support backpack strap worn by Apollo 12 commander Pete Conrad on the moon’s surface, selling for more than $36,000; a U.S. flag from Apollo 15 astronaut Al Worden’s spacesuit, with bids already above $20,000; and a drawing depicting NASA’sMercury and Gemini spacecraft autographed by all of the astronauts who flew on the capsules, at $25,000.
ANNAPOLIS, MD (June 16, 2015) – At the Paris Air Show, Maryland Lt. Governor Boyd Rutherford joined with SURVICE Engineering Co., a Belcamp, Md.-based defense firm, and U.K.-based Malloy Aeronautics, an aeronautical engineering firm, to announce that the two companies have teamed up on the development of Hoverbike technology for the U.S. Department of Defense. SURVICE and Malloy are working on the Hoverbike as part of an ongoing research and development contract with the U.S. Army Research Laboratory. The Hoverbike is being developed to operate as a new class of Tactical Reconnaissance Vehicle (TRV).
As part of this strategic alliance, Malloy Aeronautics has also announced that they have established a U.S. office in Belcamp adjacent to Aberdeen Proving Ground to complete work on the Hoverbike. A model of the Hoverbike is on display at the Paris Air Show, which runs through June 21.
“I am pleased to join with SURVICE Engineering and Malloy Aeronautics to announce their partnership on the Hoverbike, which represents a new frontier in aviation,” said Lt. Governor Rutherford. “We are also very excited to welcome Malloy and look forward to working with them to grow their operations in Maryland.”
“Establishing an office in Maryland was a clear business decision,” said Chris Malloy, managing director of Malloy Aeronautics. “The proximity to the Army Research Laboratory and U.S. defense decision makers, access to the world-class facilities through the laboratory’s Open Campus initiative, and the co-location with our strategic business partner, SURVICE Engineering, were all factors in favor of Maryland as the best choice for Malloy Aeronautics.”
“Maryland companies do a tremendous amount of research and development (R&D) for the U.S. military,” said Jeff Foulk, SURVICE chief executive officer. “If there is a new military technology being developed, there’s a good chance that some aspect was designed, built or tested in Maryland.”
With about 400 employees, SURVICE is a specialty engineering firm that has been providing R&D support for the U.S. Department of Defense and other industry sectors for more than 30 years. Formed in 2012, Malloy Aeronautics is an entrepreneurial aerospace company that develops, markets, and sells drones and Hoverbike technology to commercial and military markets.
The U.S. Army Research Laboratory is the nation’s premier laboratory for land forces and is part of the U.S. Army Research, Development and Engineering Command, which has the mission to develop technology and engineering solutions for America’s Soldiers. RDECOM is a major subordinate command of the U.S. Army Materiel Command.
The closer we get to Ceres, the more intriguing the distant dwarf planet becomes. New images of Ceres from NASA’s Dawn spacecraft provide more clues about its mysterious bright spots, and also reveal a pyramid-shaped peak towering over a relatively flat landscape.
A cluster of mysterious bright spots on dwarf planet Ceres can be seen in this image, taken by NASA’s Dawn spacecraft from an altitude of 2,700 miles (4,400 kilometers). The image, with a resolution of 1,400 feet (410 meters) per pixel, was taken on June 9, 2015. Image Credit: NASA/ JPL-Caltech /UCLA /MPS /DLR /IDA
Close up of the bright spots.
“The surface of Ceres has revealed many interesting and unique features. For example, icy moons in the outer solar system have craters with central pits, but on Ceres central pits in large craters are much more common. These and other features will allow us to understand the inner structure of Ceres that we cannot sense directly,” said Carol Raymond, deputy principal investigator for the Dawn mission, based at NASA’s Jet Propulsion Laboratory in Pasadena, California.
Dawn has been studying the dwarf planet in detail from its second mapping orbit, which is 2,700 miles (4,400 kilometers) above Ceres. A new view of its intriguing bright spots, located in a crater about 55 miles (90 kilometers) across, shows even more small spots in the crater than were previously visible.
At least eight spots can be seen next to the largest bright area, which scientists think is approximately 6 miles (9 kilometers) wide. A highly reflective material is responsible for these spots — ice and salt are leading possibilities, but scientists are considering other options, too.
Dawn’s visible and infrared mapping spectrometer allows scientists to identify specific minerals present on Ceres by looking at how light is reflected. Each mineral reflects the range of visible and infrared-light wavelengths in a unique way, and this signature helps scientists determine the components of Ceres. So, as the spacecraft continues to send back more images and data, scientists will learn more about the mystery bright spots.
In addition to the bright spots, the latest images also show a mountain with steep slopes protruding from a relatively smooth area of the dwarf planet’s surface. The structure rises about 3 miles (5 kilometers) above the surface.
Among the fascinating features on dwarf planet Ceres is an intriguing mountain protruding from a relatively smooth area. Scientists estimate that this structure rises about 3 miles (5 kilometers) above the surface. NASA’s Dawn spacecraft took this image from an altitude of 2,700 miles (4,400 kilometers). The image, with a resolution of 1,400 feet (410 meters) per pixel, was taken on June 6, 2015. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
A crop of the image around the mountain.
Ceres also has numerous craters of varying sizes, many of which have central peaks. There is ample evidence of past activity on the surface, including flows, landslides and collapsed structures. It seems that Ceres shows more remnants of activity than the protoplanet Vesta, which Dawn studied intensively for 14 months in 2011 and 2012.
Dawn is the first mission to visit a dwarf planet, and the first to orbit two distinct targets in our solar system. It arrived at Ceres, the largest object in the main asteroid belt between Mars and Jupiter, on March 6, 2015.
A variety of craters and other geological features can be found on dwarf planet Ceres. NASA’s Dawn spacecraft took this image of Ceres from an altitude of 2,700 miles (4,400 kilometers). The image, with a resolution of 1,400 feet (410 meters) per pixel, was taken on June 5, 2015. Image credit: NASA/JPL- Caltech/ UCLA /MPS /DLR / IDA
Dawn will remain in its current altitude until June 30, continuing to take images and spectra of Ceres in orbits of about three days each. It then will move into its next orbit at an altitude of 900 miles (1,450 kilometers), arriving in early August.
Dawn’s mission is managed by JPL for NASA’s Science Mission Directorate in Washington. Dawn is a project of the directorate’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team.
This image, taken by NASA’s Dawn spacecraft, shows an intriguing mountain on dwarf planet Ceres protruding from a relatively smooth area. Scientists estimate that this structure rises about 3 miles (5 kilometers) above the surface. Dawn captured this image from an altitude of 2,700 miles (4,400 kilometers). The image, with a resolution of 1,400 feet (410 meters) per pixel, was taken on June 14, 2015. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA