by Paul Gilster | Feb 14, 2005 | Deep Sky Astronomy & Telescopes
A star that apparently had a close encounter with the black hole at the center of the Milky Way is now speeding out of the galaxy at some 1.5 million miles per hour. That’s the conclusion of astronomers at the Harvard-Smithsonian Center for Astrophysics (CfA), who say the star is moving fast enough to have achieved galactic escape velocity. “We have never before seen a star moving fast enough to completely escape the confines of our galaxy,” said co-discoverer Warren Brown (CfA). “We’re tempted to call it the outcast star because it was forcefully tossed from its home.”
The star is catalogued as SDSS J090745.0+24507; it was apparently a member of a binary system before its close brush with the black hole. According to the scientists’ scenario, the companion star was pulled into orbit around the black hole while the outcast star was flung on a trajectory that will take it out of the galaxy entirely.
Image: Astronomers at the Smithsonian Astrophysical Observatory have discovered the first star flung out of the Milky Way, speeding away at over 1.5 million miles per hour. This tremendous speed likely resulted from a close encounter with the massive black hole at the center of the Milky Way. The so-called outcast star is shown in this artist’s depiction in its current location as it travels through the distant outskirts of the Milky Way. Credit: Ruth Bazinet, CfA
From a CfA press release:
Its composition and age provide additional proof of the star’s history. The fastest star contains many elements heavier than hydrogen and helium, which astronomers collectively call metals. “Because this is a metal-rich star, we believe that it recently came from a star-forming region like that in the galactic center,” said Brown. Less than 80 million years were needed for the star to reach its current location, which is consistent with its estimated age.
The paper outlining the find (with co-authors Margaret J. Geller, Scott J. Kenyon and Michael J. Kurtz) will appear in The Astrophysical Journal.
by Paul Gilster | Feb 14, 2005 | Breakthrough Propulsion, Sail Concepts
The Space Technology and Applications International Forum (STAIF) opens today in Albuquerque. That makes New Mexico the place to be for new propulsion concepts and mission studies — STAIF-2005 hosts six concurrent conferences organized by the University of New Mexico’s Institute for Space and Nuclear Power Studies, and attendance is international in scope. Everything is on the table, from low-cost launch vehicles to nuclear propulsion, from robotics concepts for deep space missions to quantum entanglement.
The proceedings of STAIF-2005 will be published by the American Institute of Physics, but Centauri Dreams will be digging around before then trying to come up with information on interstellar issues presented at the conference. Papers that catch the eye from a quick glance through this massive program:
“The GEM (Gravity-Electro-Magnetism) Theory of Field Unification and its Application to Human Flight and Gravity Wave Production and Detection” — John Brandenburg, Florida Space Institute-University of Central Florida, Kennedy Space Center, Florida
“The Innovative Interstellar Explorer ‘Vision Mission'” — R. L. McNutt, Jr., R. E. Gold, S. M. Krimigis, Johns Hopikins University et al.
“Teleportation via Wormhole-Stargates” — Eric W. Davis, Institute for Advanced Studies, Austin TX
“Propulsion Challenges and Mach Effects” — James F. Woodward, California State University, Fullerton, CA
“Universal Entanglement, Moessbauer Qubits, Equivalence and Mach’s Principles and, All That” — Ciprian Ciubotariu, Universite Laval, Laval, Quebec, Canada
“The Plasma Magnet for Sailing the Solar Wind” — John Slough, University of Washington, Seattle, WA
“Advancements in Dense Plasma Focus (DPF) for Space Propulsion” — Robert Thomas, Yang Yang, G.H. Miley, University of Illinois at Urbana-Champaign, Urbana, IL; F.B. Mead, Air Force Research Laboratory, Edwards AFB, CA
“Antimatter Driven Sail for Deep Space Missions” — Steven D. Howe and Gerald P. Jackson, Hbar Technologies, LLC, West Chicago, IL
“Antiproton Powered Gas Core Fission Rocket” — Terry Kammash, University of Michigan, Ann Arbor, MI
“A Perspective of Practical Interstellar Exploration: Using Field Propulsion and Hyper-Space Navigation Theory” — Y. Minami, NEC Patent Service, Ltd., Tokyo, Japan
These sessions are only a suggestion of the riches STAIF-2005 offers. We’ll be discussing many of these concepts in coming weeks.
by Paul Gilster | Feb 12, 2005 | Culture and Society
“The space effort is very simply a continuation of the expansion of ecological range, which has been occurring at an accelerating rate throughout the evolutionary history of Man… Successful extraterrestrial colonization, for example, might be counted as an evolutionary ‘success,’ and unsuccessful colonization–abandonment of the space effort–as an evolutionary ‘failure…’ Space exploration should be considered primarily as a biological thrust outward for the human species, and not just another step toward making life easier through a speedup in technology.”
Ward J. Haas, “The Biological Significance of the Space Effort”, Annals of the New York Academy of Science, Vol. 140 (1966), pp. 659-666. First noted in Sylvia Engdahl’s Space Quotes to Ponder pages.
Centauri Dreams note: The attempt to defend space exploration on the grounds of near-term technological benefits, though well-meaning, has always betrayed a lack of imagination. The human movement into space only makes sense when seen in the context of the biological imperative to explore. It is an imperative that seems hard-coded in the human genome, one that has manifested itself throughout history. Interstellar exploration may seem improbable, but it is in all likelihood inescapable.
by Paul Gilster | Feb 11, 2005 | Exoplanetary Science |
If the name Alex Wolszczan (pronounced VOL-shtan) isn’t immediately familiar, it may be because we’ve become so inured to new extrasolar planet discoveries that we’ve forgotten about the first. But it was Pennsylvania State University’s Wolszczan who, in 1991, was the first to detect planets outside our Solar System, around the pulsar PSR B1257+12, an incredibly dense neutron star that is the remnant of a once massive star in the constellation Virgo some 1500 light years away.
These were the first new planets discovered since Clyde Tombaugh’s detection of Pluto in 1930, and Wolszczan was able to learn a surprising amount about them. Using the Arecibo radio telescope in Puerto Rico, he found that two of them were roughly similar in mass to the Earth, while the other corresponded roughly to the mass of the Moon. Their spacing around the primary corresponded to that between Mercury, Venus and the Earth around our Sun.
Image: An artist’s conception of one of the planets around the pulsar PSR 1257+12. Note the intense aurora, the result of the continuing bombardment of radiation from the pulsar. Copyright Lynette Cook, and used with her permission (http://extrasolar.spaceart.org)
Now from the Winter Conference on Astrophysics in Aspen comes a new discovery around the same pulsar: a fourth planet, roughly as far from the pulsar as the asteroid belt is from the Sun. Caltech’s Maciej Konacki is co-discoverer of the new planet along with Wolszczan:
“Because our observations practically rule out a possible presence of an even more distant, massive planet or planets around the pulsar, it is quite possible that the tiny fourth planet is the largest member of a cloud of interplanetary debris at the outer edge of the pulsar’s planetary system, a remnant of the original protoplanetary disk that created the three inner planets,” Wolszczan explained. The small planet, about one-fifth of the mass of Pluto, may occupy the same outer-boundary position in its planetary system as Pluto does in our solar system. “Surprisingly, the planetary system around this pulsar resembles our own solar system more than any extrasolar planetary system discovered around a Sun-like star,” Konacki said.
So how do we detect planets as small as Earth’s Moon around a star 1500 light years away? Pulsars turn out to be quite useful for detecting planetary wobbles — they pulse with a degree of accuracy known only to the finest atomic clocks. That makes detections down to asteroid size a possibility, a feat not yet possible with the stellar wobbles used by optical astronomers around more conventional main sequence stars.
This press release from PSU leaves us with an intriguing question:
The very existence of the pulsar planets may represent convincing evidence that Earth-mass planets form just as easily as do the gas giants that are known to exist around more than 5 percent of the nearby Sun-like stars. However, Wolszczan said, “the message carried by the pulsar planets may equally well be that the formation of Earth-like planets requires special conditions, making such planets a rarity. For example, there is growing evidence that a nearby supernova explosion may have played an important role in our solar system’s formation.” Future space observatories, including the Kepler and the Space Interferometry Missions, and the Terrestrial Planet Finder, will play a decisive role in making a distinction between these fundamental alternatives.
Wolszczan maintains a Pulsar Planets page at PSU with background on the first extrasolar planet detections. He presented the paper “A Pluto-Mass Body and Ionized Gas in the PSR B1257+12 Planetary System” at the Aspen conference on February 11.
by Paul Gilster | Feb 10, 2005 | Exoplanetary Science
The 2005 Winter Conference on Astrophysics is now in session in Aspen, with papers running through tomorrow. The topics here make up a wish list for those interested in learning more about the next steps in extrasolar planet detection and analysis. Tomorrow’s last session, for example, is on new technologies for detection, includng the Terrestrial Planet Finder mission. Earlier sessions have included everything from theories of giant planet formation to planetesimals and how they form in protoplanetary disks.
But the first story out of the conference to hit the media was the detection of possible planets around a small brown dwarf called OTS 44, which is only 15 times the mass of Jupiter — before now, the smallest brown dwarf implicated in debris disk formation was almost 30 times the mass of Jupiter. You can see how this hypothetical planetary system scales next to our own in the image below. OTS 44 is approximately 500 light years away in the Chameleon constellation.
Image: This artist’s conception shows the relative size of a hypothetical brown dwarf-planetary system (below) compared to our own solar system.
A brown dwarf is a cool or “failed” star, which lacks the mass to ignite and shine like our Sun. NASA’s Spitzer Space Telescope set its infrared eyes on an extraordinarily low-mass brown dwarf called OTS 44 and found a swirling disk of planet-building dust. At only 15 times the mass of Jupiter, OTS 44 is the smallest known brown dwarf to host a planet-forming, or protoplanetary, disk.
Astronomers believe that this unusual system will eventually spawn planets. If so, they speculate that OTS 44’s disk has enough mass to make one small gas giant and a few Earth-sized rocky planets.
Examples of these possible planets are depicted at the bottom of this picture, circling a low-mass brown dwarf. Above, the bodies of our own solar system have been drawn to the same scale. In each system, the terrestrial planets have been enlarged and the distances between the planets and their parent bodies have been scaled down for easier viewing.” Credit: NASA/JPL-Caltech/T. Pyle (SSC).
This work, which was carried out using NASA’s Spitzer Space Telescope (see the Spitzer press release here) raises some interesting speculations. “There may be a host of miniature solar systems out there, in which planets orbit brown dwarfs,” said Dr. Kevin Luhman, lead author of the new study from the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass. “This leads to all sorts of new questions, like ‘Could life exist on such planets?’ or ‘What do you call a planet circling a planet-sized body? A moon or a planet?'”
Another interesting setting for science fiction:
“If life did exist in this system, it would have to constantly adjust to the dwindling temperatures of a brown dwarf,” said Luhman. “For liquid water to be present, the planet would have to be much closer to the brown dwarf than Earth is to our Sun.”
“It’s exciting to speculate about the possibilities for life in such as system, of course at this point we are only beginning to understand the unusual circumstances under which planets arise,” he added.
The paper “Spitzer Identification of the Least Massive Known Brown Dwarf with a Circumstellar Disk,” by Luhman, Alession, Calvet et.al., will appear in the February 10 issue of The Astrophysical Journal Letters and is available from the Spitzer site (PDF warning).
Much more about the Aspen conference after I get over the flu — there is material galore in these proceedings.
