Hyperactive Hartley 2 has a split history, comet-exploring spacecraft finds

ScienceDaily (Oct. 5, 2011) — The latest analysis of data from NASA's Deep Impact spacecraft shows that comet 103P/Hartley 2 is hyperactive in terms of the material it spews out, compared to the other comets observed up close to date. The comet also shows surprising diversity -- ice on the comet's sunlit surface is found in patches that are isolated from areas of dust. In addition, one lobe of the dog-bone shaped comet may have lost much more of the primordial material from the formation of the comet than the other, suggesting that Hartley 2 was originally two comets that came together in a gentle collision.

Mike A'Hearn and Lori Feaga are presenting their findings at the EPSC-DPS Joint Meeting 2011 in Nantes, France.

Deep Impact made its closest encounter of Hartley 2 on Nov. 4, 2010. Over the past year, the science team has been pouring over the data to gain a more detailed understanding of the processes that drive the comet's activity.

"Hartley 2 works differently from Tempel 1, which was encountered by Deep Impact in 2005 and from Wild 2, which was observed by the Stardust mission. It ejects a huge amount of material for its size. Halley, which was observed by the Giotto mission lies somewhere in the middle of the spectrum of activity. Since the encounter, we have been able to dig deeper into the data and have provided more evidence of how ice and dust is released from the nucleus," said A'Hearn, the Principal Investigator of Deep Impact's mission extension, EPOXI.

Carbon dioxide gas, or dry ice, sublimates beneath the comet's surface when it feels heat from the Sun and this fuels extensive jet activity on the comet. Much more carbon dioxide is escaping Hartley 2 than the other comets observed, including Tempel 1. The Deep Impact cameras and spectrometer have observed fragile chunks of water ice and dust being dragged from the nucleus with the escaping carbon dioxide into the comet's atmosphere, or coma. The latest results are giving the team a better understanding of the nucleus and how the micrometre-sized grains of pure ice and centimetre sized dust particles are released from Hartley 2 into the coma. They have found that, despite the hyperactive release of material, both the ice and the volatiles within the dust are actually moving and subliming very slowly.

The team has found a large region of bright, rough terrain on the surface that is covered in water ice particles, a few hundredths of a millimetre in size. Through a combination of surface temperature analysis and the fact that the ice exists on the sunlit surface, they have deduced that these ice particles must be physically separate from the warm, dark dust and not intimately mixed.

Although inferred by the wealth of approach and departure data and preliminary mapping of the coma at closest approach, the team has also definitively reported that the larger lobe of Hartley 2's nucleus currently has less carbon dioxide being released from it than the smaller lobe. This means that the volatile ices, primordial material from the formation of the comet located tens of centimetres deep into the nucleus, may be depleted in the larger lobe.

Lori Feaga, from the University of Maryland, says, "The heterogeneity between lobes is most likely due to compositional differences in the originally accreted material."

"We are speculating that this means that the two lobes of the comet formed in different places in the Solar System. They came together in a gradual collision and the central part of the dog-bone was in-filled with dust and ice from the debris," adds A'Hearn

From observations made from telescopes here on Earth, Deep Impact collaborators Matthew Knight and David Schleicher have shown that the grains are gradually shedding water and all the material is slowly moving away from the sun. This result complements the findings from the spacecraft team.

A'Hearn concludes, "All of these detailed findings put together, those from the spacecraft and supporting ground-based telescopes, may require us to rethink cometary origins."

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Erasing history? Temporal cloaks adjust light's throttle to hide an event in time

ScienceDaily (Oct. 13, 2011) — Researchers from Cornell University in Ithaca, N.Y., have demonstrated for the first time that it's possible to cloak a singular event in time, creating what has been described as a "history editor." In a feat of Einstein-inspired physics, Moti Fridman and his colleagues sent a beam of light traveling down an optical fiber and through a pair of so-called "time lenses." Between these two lenses, the researchers were able to briefly create a small bubble, or gap, in the flow of light. During that fleetingly brief moment, lasting only the tiniest fraction of a second, the gap functioned like a temporal hole, concealing the fact that a brief burst of light ever occurred.

The team is presenting their findings at the Optical Society's (OSA) Annual Meeting, Frontiers in Optics (FiO) 2011 (http://www.frontiersinoptics.com/), taking place in San Jose, Calif. next week.

Their ingenious system, which is the first physical demonstration of a phenomenon originally described theoretically a year ago by Martin McCall and his colleagues at Imperial College London in the Journal of Optics, relies on the ability to use short intense pulses of light to alter the speed of light as it travels through optical materials, in this case an optical fiber. (In a vacuum, light maintains its predetermined speed limit of 180,000 miles per second.) As the beam passes through a split-time lens (a silicon device originally designed to speed up data transfer), it accelerates near the center and slows down along the edges, causing it to balloon out toward the edges, leaving a dead zone around which the light waves curve. A similar lens a little farther along the path produces the exact but opposite velocity adjustments, resetting the speeds and reproducing the original shape and appearance of the light rays.

To test the performance of their temporal cloak, the researchers created pulses of light directly between the two lenses. The pulses repeated like clockwork at a rate of 41 kilohertz. When the cloak was off, the researchers were able to detect a steady beat. By switching on the temporal cloak, which was synchronized with the light pulses, all signs that these events ever took place were erased from the data stream.

Unlike spatial optical cloaking, which typically requires the use of metamaterials (specially created materials engineered to have specific optical properties), the temporal cloak designed by the researchers relies more on the fundamental properties of light and how it behaves under highly constrained space and time conditions. The area affected by the temporal cloak is a mere 6 millimeters long and can last only 20 trillionths of a second. The length of the cloaked area and the length of time it is able to function are tightly constrained -- primarily by the extreme velocity of light. Cloaking for a longer duration would create turbulence in the system, essentially pulling back the curtain and hinting that an event had occurred. Also, to achieve any measurable macroscopic effects, an experiment of planetary and even interplanetary scales would be necessary.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Optical Society of America, via EurekAlert!, a service of AAAS.

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Erasing history? Temporal cloaks adjust light's throttle to hide an event in time

ScienceDaily (Oct. 13, 2011) — Researchers from Cornell University in Ithaca, N.Y., have demonstrated for the first time that it's possible to cloak a singular event in time, creating what has been described as a "history editor." In a feat of Einstein-inspired physics, Moti Fridman and his colleagues sent a beam of light traveling down an optical fiber and through a pair of so-called "time lenses." Between these two lenses, the researchers were able to briefly create a small bubble, or gap, in the flow of light. During that fleetingly brief moment, lasting only the tiniest fraction of a second, the gap functioned like a temporal hole, concealing the fact that a brief burst of light ever occurred.

The team is presenting their findings at the Optical Society's (OSA) Annual Meeting, Frontiers in Optics (FiO) 2011 (http://www.frontiersinoptics.com/), taking place in San Jose, Calif. next week.

Their ingenious system, which is the first physical demonstration of a phenomenon originally described theoretically a year ago by Martin McCall and his colleagues at Imperial College London in the Journal of Optics, relies on the ability to use short intense pulses of light to alter the speed of light as it travels through optical materials, in this case an optical fiber. (In a vacuum, light maintains its predetermined speed limit of 180,000 miles per second.) As the beam passes through a split-time lens (a silicon device originally designed to speed up data transfer), it accelerates near the center and slows down along the edges, causing it to balloon out toward the edges, leaving a dead zone around which the light waves curve. A similar lens a little farther along the path produces the exact but opposite velocity adjustments, resetting the speeds and reproducing the original shape and appearance of the light rays.

To test the performance of their temporal cloak, the researchers created pulses of light directly between the two lenses. The pulses repeated like clockwork at a rate of 41 kilohertz. When the cloak was off, the researchers were able to detect a steady beat. By switching on the temporal cloak, which was synchronized with the light pulses, all signs that these events ever took place were erased from the data stream.

Unlike spatial optical cloaking, which typically requires the use of metamaterials (specially created materials engineered to have specific optical properties), the temporal cloak designed by the researchers relies more on the fundamental properties of light and how it behaves under highly constrained space and time conditions. The area affected by the temporal cloak is a mere 6 millimeters long and can last only 20 trillionths of a second. The length of the cloaked area and the length of time it is able to function are tightly constrained -- primarily by the extreme velocity of light. Cloaking for a longer duration would create turbulence in the system, essentially pulling back the curtain and hinting that an event had occurred. Also, to achieve any measurable macroscopic effects, an experiment of planetary and even interplanetary scales would be necessary.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Optical Society of America, via EurekAlert!, a service of AAAS.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Hyperactive Hartley 2 has a split history, comet-exploring spacecraft finds

ScienceDaily (Oct. 5, 2011) — The latest analysis of data from NASA's Deep Impact spacecraft shows that comet 103P/Hartley 2 is hyperactive in terms of the material it spews out, compared to the other comets observed up close to date. The comet also shows surprising diversity -- ice on the comet's sunlit surface is found in patches that are isolated from areas of dust. In addition, one lobe of the dog-bone shaped comet may have lost much more of the primordial material from the formation of the comet than the other, suggesting that Hartley 2 was originally two comets that came together in a gentle collision.

Mike A'Hearn and Lori Feaga are presenting their findings at the EPSC-DPS Joint Meeting 2011 in Nantes, France.

Deep Impact made its closest encounter of Hartley 2 on Nov. 4, 2010. Over the past year, the science team has been pouring over the data to gain a more detailed understanding of the processes that drive the comet's activity.

"Hartley 2 works differently from Tempel 1, which was encountered by Deep Impact in 2005 and from Wild 2, which was observed by the Stardust mission. It ejects a huge amount of material for its size. Halley, which was observed by the Giotto mission lies somewhere in the middle of the spectrum of activity. Since the encounter, we have been able to dig deeper into the data and have provided more evidence of how ice and dust is released from the nucleus," said A'Hearn, the Principal Investigator of Deep Impact's mission extension, EPOXI.

Carbon dioxide gas, or dry ice, sublimates beneath the comet's surface when it feels heat from the Sun and this fuels extensive jet activity on the comet. Much more carbon dioxide is escaping Hartley 2 than the other comets observed, including Tempel 1. The Deep Impact cameras and spectrometer have observed fragile chunks of water ice and dust being dragged from the nucleus with the escaping carbon dioxide into the comet's atmosphere, or coma. The latest results are giving the team a better understanding of the nucleus and how the micrometre-sized grains of pure ice and centimetre sized dust particles are released from Hartley 2 into the coma. They have found that, despite the hyperactive release of material, both the ice and the volatiles within the dust are actually moving and subliming very slowly.

The team has found a large region of bright, rough terrain on the surface that is covered in water ice particles, a few hundredths of a millimetre in size. Through a combination of surface temperature analysis and the fact that the ice exists on the sunlit surface, they have deduced that these ice particles must be physically separate from the warm, dark dust and not intimately mixed.

Although inferred by the wealth of approach and departure data and preliminary mapping of the coma at closest approach, the team has also definitively reported that the larger lobe of Hartley 2's nucleus currently has less carbon dioxide being released from it than the smaller lobe. This means that the volatile ices, primordial material from the formation of the comet located tens of centimetres deep into the nucleus, may be depleted in the larger lobe.

Lori Feaga, from the University of Maryland, says, "The heterogeneity between lobes is most likely due to compositional differences in the originally accreted material."

"We are speculating that this means that the two lobes of the comet formed in different places in the Solar System. They came together in a gradual collision and the central part of the dog-bone was in-filled with dust and ice from the debris," adds A'Hearn

From observations made from telescopes here on Earth, Deep Impact collaborators Matthew Knight and David Schleicher have shown that the grains are gradually shedding water and all the material is slowly moving away from the sun. This result complements the findings from the spacecraft team.

A'Hearn concludes, "All of these detailed findings put together, those from the spacecraft and supporting ground-based telescopes, may require us to rethink cometary origins."

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Europlanet Media Centre, via AlphaGalileo.

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Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

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Cosmic weight watching reveals black hole-galaxy history

ScienceDaily (Sep. 29, 2011) — Using state-of-the-art technology and sophisticated data analysis tools, a team of astronomers from the Max Planck Institute for Astronomy has developed a new and powerful technique to directly determine the mass of an active galaxy at a distance of nearly 9 billion light-years from Earth. This pioneering method promises a new approach for studying the co-evolution of galaxies and their central black holes. First results indicate that for galaxies, the best part of cosmic history was not a time of sweeping changes.

One of the most intriguing developments in astronomy over the last few decades is the realization that not only do most galaxies contain central black holes of gigantic size, but also that the mass of these central black holes are directly related to the mass of their host galaxies. This correlation is predicted by the current standard model of galaxy evolution, the so-called hierarchical model, as astronomers from the Max Planck Institute for Astronomy have recently shown.

When astronomers look out to greater and greater distances, they look further and further into the past. Investigating this black hole-galaxy mass correlation at different distances, and thus at different times in cosmic history, allows astronomers to study galaxy and black hole evolution in action.

For galaxies further away than 5 billion light-years (corresponding to a redshift of z > 0.5), such studies face considerable difficulties. The typical objects of study are so-called active galaxies, and there are well-established methods to estimate the mass of such a galaxy's central black hole. It is the galaxy's mass itself that is the challenge: At such distances, standard methods of estimating a galaxy's mass become exceedingly uncertain or fail altogether.

Now, a team of astronomers from the Max Planck Institute for Astronomy, led by Dr Katherine Inskip, has, for the first time, succeeded in directly "weighing" both a galaxy and its central black hole at such a great distance using a sophisticated and novel method. The galaxy, known to astronomers by the number J090543.56+043347.3 (which encodes the galaxy's position in the sky) has a distance of 8.8 billion light-years from Earth (redshift z = 1.3).

The astronomers succeeded in measuring directly the so-called dynamical mass of this active galaxy. The key idea is the following: A galaxy's stars and gas clouds orbit the galactic centre; for instance, our Sun orbits the centre of the Milky Way galaxy once every 250 million years. The stars' different orbital speeds are a direct function of the galaxy's mass distribution. Determine orbital speeds and you can determine the galaxy's total mass.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Max-Planck-Gesellschaft.

Journal Reference:

K. J. Inskip, K. Jahnke, H.-W. Rix, G. van de Ven. Resolving the Dynamical Mass of a z ~ 1.3 Quasi-stellar Object Host Galaxy Using SINFONI and Laser Guide Star Assisted Adaptive Optics. The Astrophysical Journal, 2011; 739 (2): 90 DOI: 10.1088/0004-637X/739/2/90

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Cosmic weight watching reveals black hole-galaxy history

ScienceDaily (Sep. 29, 2011) — Using state-of-the-art technology and sophisticated data analysis tools, a team of astronomers from the Max Planck Institute for Astronomy has developed a new and powerful technique to directly determine the mass of an active galaxy at a distance of nearly 9 billion light-years from Earth. This pioneering method promises a new approach for studying the co-evolution of galaxies and their central black holes. First results indicate that for galaxies, the best part of cosmic history was not a time of sweeping changes.

One of the most intriguing developments in astronomy over the last few decades is the realization that not only do most galaxies contain central black holes of gigantic size, but also that the mass of these central black holes are directly related to the mass of their host galaxies. This correlation is predicted by the current standard model of galaxy evolution, the so-called hierarchical model, as astronomers from the Max Planck Institute for Astronomy have recently shown.

When astronomers look out to greater and greater distances, they look further and further into the past. Investigating this black hole-galaxy mass correlation at different distances, and thus at different times in cosmic history, allows astronomers to study galaxy and black hole evolution in action.

For galaxies further away than 5 billion light-years (corresponding to a redshift of z > 0.5), such studies face considerable difficulties. The typical objects of study are so-called active galaxies, and there are well-established methods to estimate the mass of such a galaxy's central black hole. It is the galaxy's mass itself that is the challenge: At such distances, standard methods of estimating a galaxy's mass become exceedingly uncertain or fail altogether.

Now, a team of astronomers from the Max Planck Institute for Astronomy, led by Dr Katherine Inskip, has, for the first time, succeeded in directly "weighing" both a galaxy and its central black hole at such a great distance using a sophisticated and novel method. The galaxy, known to astronomers by the number J090543.56+043347.3 (which encodes the galaxy's position in the sky) has a distance of 8.8 billion light-years from Earth (redshift z = 1.3).

The astronomers succeeded in measuring directly the so-called dynamical mass of this active galaxy. The key idea is the following: A galaxy's stars and gas clouds orbit the galactic centre; for instance, our Sun orbits the centre of the Milky Way galaxy once every 250 million years. The stars' different orbital speeds are a direct function of the galaxy's mass distribution. Determine orbital speeds and you can determine the galaxy's total mass.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Max-Planck-Gesellschaft.

Journal Reference:

K. J. Inskip, K. Jahnke, H.-W. Rix, G. van de Ven. Resolving the Dynamical Mass of a z ~ 1.3 Quasi-stellar Object Host Galaxy Using SINFONI and Laser Guide Star Assisted Adaptive Optics. The Astrophysical Journal, 2011; 739 (2): 90 DOI: 10.1088/0004-637X/739/2/90

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Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Early history of genetics revised: New light shed on 'rediscovery' of Mendel's laws of heredity

ScienceDaily (May 3, 2011) — The early history of genetics has to be re-written in the light of new findings. Scientists from the University Jena (Germany) in co-operation with colleagues from Prague found out that the traditional history of the 'rediscovery' of Gregor Johann Mendel's laws of heredity in 1900 has to be adjusted and some facets have to be added.

It all began in the year of 1865: Mendel, today known as the 'father of genetics', published his scientific findings about the cross breeding experiments of peas, that went largely unnoticed during his lifetime. His research notes and manuscripts disappeared after Mendel's death in 1884. Only about 1900 three scientists 'rediscovered' the later so called Mendel's laws: the Dutch biologist Hugo de Vries, the German plant geneticist Carl Correns, and the Austrian plant breeder Erich von Tschermak-Seysenegg.

"For 110 years many believed it to be like that," says Prof. Dr. Uwe Hoßfeld, leader of the Research Group Didactics of Biology of the University Jena. "But in reality there were four direct protagonists, 'rediscoverers' of Mendel's laws" as the historians of science and biologists found out recently. Moreover it was assumed that the research went on in parallel and independently. "The so far unknown and now edited correspondence of the brothers Armin und Erich von Tschermak-Seysenegg from 1898-1901 leads to a correction of the former assumption," according to Dr. Michal Simunek. Amongst other things the researchers could prove that some of the scientists should indeed exchange plant seeds and corresponded about the research results in their letters.

Recently two volumes dealing with selected problems of the early Mendel research from the scientific series 'Studies in the History of Sciences and Humanities' have been published. Volume No. 27 for the first time releases the so far unknown personal correspondence from the period between 1898-1951 of the brothers Armin and Erich von Tschermak-Seysenegg, the former being physiologist and the latter a plant breeder. The vast majority of them has been identified by Dr. Simunek in the family possession of Armin's grandson, Dr. Armin Tschermak von Seysenegg Jr. From 1900 Armin Tschermak von Seysenegg presented several writings which show that apart from de Vries and Correns his younger brother Erich took part in the research about Mendel's laws. However he excluded himself from the ranks of the so-called rediscoverers in spite of his active participation in the events of 1900 and 1901.

What were the reasons? Why did he step back and leave all the glory to his younger brother Erich? "The two of them were tied by such an unusual brotherly love that is otherwise rare amongst scientists," Hoßfeld reports on one possible reason. Erich took the credit as the 'rediscoverer' for a long time. He died in 1962. Armin, who died ten years earlier, however remained unknown person about these particular achievements to the public and thus allowed his brother's to overshadow him. At the same time the eye physiologist and later professor in Prague seemed to contribute especially as far as the statistical analysis concerned. Armin was widely interested in the subject of Mendel's laws (especially in the numeric ratio). Therefore his younger brother extensively consulted him on these problems. It can be assumed that the papers Erich Tschermak von Seysenegg presented in 1900 and 1901 respectively about the 'rediscovery' were actually the results of an intense co-operation with his older brother Armin. It is difficult though to reconstruct the whole amount of this fraternal teamwork as there are only a few of the older brother's letters still surviving. "After these new findings the traditional view of the early history of genetics has to be reviewed," both scientists are sure.

The second contribution to the history of the Gregor J. Mendel related research (Volume No. 28) contains the correspondence of Mendel's first biographers, among them Willam Bateson, Hugo Iltis and Erich Tschermak von Seysenegg, with Mendel's two nephews, Dr. Alois and Ferdinand Schindler, from the period between 1902-35. After 1900 the nephews became the most important sources for the biographical portrayal of Gregor J. Mendel. Their writings are mostly concerned with the family history and the last part of Mendel's life. This correspondence is published in such comprehensive volume for the first time.

In the German Research Council project about the early history of genetics in Bohemia and Moravia, Jena scientists co-operated with researchers from the Academy of Sciences in Prague as well as the Moravian Museum in Brno.

References:

Michal Simunek, Uwe Hoßfeld, Florian Thümmler, Olaf Breidbach (Eds.): The Mendelian Dioskuri -- Correspondence of Armin with Erich von Tschermak-Seysenegg, 1898-1951; „Studies in the History of Sciences and Humanities," Vol. No. 27; Prag 2011; ISBN 978-80-87378-67-0

Michal Simunek, Uwe Hoßfeld, Florian Thümmler, Jirí Sekerák (Eds.): The Letters on G. J. Mendel -- Correspondence of William Bateson, Hugo Iltis, and Erich von Tschermak-Seysenegg with Alois and Ferdinand Schindler, 1902-1935; „Studies in the History of Sciences and Humanities," Vol. No. 28; Prag 2011; ISBN 978-80-87378-73-1

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Friedrich-Schiller-Universitaet Jena.

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