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News Article | November 2, 2016
Site: phys.org

The galaxies are part of a cluster of galaxies more than 2 billion light-years from Earth. The close encounter, millions of years ago, stripped the smaller galaxy of nearly all its stars and gas. What remains is its black hole and a small galactic remnant only about 3,000 light-years across. For comparison, our Milky Way Galaxy is approximately 100,000 light-years across. The discovery was made as part of a program to detect supermassive black holes, millions or billions of times more massive than the Sun, that are not at the centers of galaxies. Supermassive black holes reside at the centers of most galaxies. Large galaxies are thought to grow by devouring smaller companions. In such cases, the black holes of both are expected to orbit each other, eventually merging. "We were looking for orbiting pairs of supermassive black holes, with one offset from the center of a galaxy, as telltale evidence of a previous galaxy merger," said James Condon, of the National Radio Astronomy Observatory. "Instead, we found this black hole fleeing from the larger galaxy and leaving a trail of debris behind it," he added. "We've not seen anything like this before," Condon said. The astronomers began their quest by using the VLBA to make very high resolution images of more than 1,200 galaxies, previously identified by large-scale sky surveys done with infrared and radio telescopes. Their VLBA observations showed that the supermassive black holes of nearly all these galaxies were at the centers of the galaxies. However, one object, in a cluster of galaxies called ZwCl 8193, did not fit that pattern. Further studies showed that this object, called B3 1715+425, is a supermassive black hole surrounded by a galaxy much smaller and fainter than would be expected. In addition, this object is speeding away from the core of a much larger galaxy, leaving a wake of ionized gas behind it. The scientists concluded that B3 1715+425 is what has remained of a galaxy that passed through the larger galaxy and had most of its stars and gas stripped away by the encounter—a "nearly naked" supermassive black hole. The speeding remnant, the scientists said, probably will lose more mass and cease forming new stars. "In a billion years or so, it probably will be invisible," Condon said. That means, he pointed out, that there could be many more such objects left over from earlier galactic encounters that astronomers can't detect. The scientists will keep looking, however. They're observing more objects, in a long-term project with the VLBA. Since their project is not time-critical, Condon explained, they use "filler time" when the telescope is not in use for other observations. "The data we get from the VLBA is very high quality. We get the positions of the supermassive black holes to extremely good precision. Our limiting factor is the precision of the galaxy positions seen at other wavelengths that we use for comparison," Condon said. With new optical telescopes that will come on line in future years, such as the Large Synoptic Survey Telescope (LSST), he said, they will then have improved images that can be compared with the VLBA images. They hope that this will allow them to discover more objects like B3 1714+425. "And also maybe some of the binary supermassive black holes we originally sought," he said. Condon worked with Jeremy Darling of the University of Colorado, Yuri Kovalev of the Astro Space Center of the Lebedev Physical Institute in Moscow, and Leonid Petrov of the Astrogeo Center in Falls Church, Virginia. The scientists are reporting their findings in the Astrophysical Journal. The VLBA, dedicated in 1993, now is part of the Long Baseline Observatory. It uses ten, 25-meter-diameter dish antennas distributed from Hawaii to St. Croix in the Caribbean. It is operated from the NRAO's Domenici Science Operations Center in Socorro, NM. All ten antennas work together as a single telescope with the greatest resolving power available to astronomy. This unique capability has produced landmark contributions to numerous scientific fields, ranging from Earth tectonics, climate research, and spacecraft navigation, to cosmology.


News Article | November 2, 2016
Site: www.eurekalert.org

Astronomers using the super-sharp radio vision of the National Science Foundation's Very Long Baseline Array (VLBA) have found the shredded remains of a galaxy that passed through a larger galaxy, leaving only the smaller galaxy's nearly-naked supermassive black hole to emerge and speed away at more than 2,000 miles per second. The galaxies are part of a cluster of galaxies more than 2 billion light-years from Earth. The close encounter, millions of years ago, stripped the smaller galaxy of nearly all its stars and gas. What remains is its black hole and a small galactic remnant only about 3,000 light-years across. For comparison, our Milky Way Galaxy is approximately 100,000 light-years across. The discovery was made as part of a program to detect supermassive black holes, millions or billions of times more massive than the Sun, that are not at the centers of galaxies. Supermassive black holes reside at the centers of most galaxies. Large galaxies are thought to grow by devouring smaller companions. In such cases, the black holes of both are expected to orbit each other, eventually merging. "We were looking for orbiting pairs of supermassive black holes, with one offset from the center of a galaxy, as telltale evidence of a previous galaxy merger," said James Condon, of the National Radio Astronomy Observatory. "Instead, we found this black hole fleeing from the larger galaxy and leaving a trail of debris behind it," he added. "We've not seen anything like this before," Condon said. The astronomers began their quest by using the VLBA to make very high resolution images of more than 1,200 galaxies, previously identified by large-scale sky surveys done with infrared and radio telescopes. Their VLBA observations showed that the supermassive black holes of nearly all these galaxies were at the centers of the galaxies. However, one object, in a cluster of galaxies called ZwCl 8193, did not fit that pattern. Further studies showed that this object, called B3 1715+425, is a supermassive black hole surrounded by a galaxy much smaller and fainter than would be expected. In addition, this object is speeding away from the core of a much larger galaxy, leaving a wake of ionized gas behind it. The scientists concluded that B3 1715+425 is what has remained of a galaxy that passed through the larger galaxy and had most of its stars and gas stripped away by the encounter -- a "nearly naked" supermassive black hole. The speeding remnant, the scientists said, probably will lose more mass and cease forming new stars. "In a billion years or so, it probably will be invisible," Condon said. That means, he pointed out, that there could be many more such objects left over from earlier galactic encounters that astronomers can't detect. The scientists will keep looking, however. They're observing more objects, in a long-term project with the VLBA. Since their project is not time-critical, Condon explained, they use "filler time" when the telescope is not in use for other observations. "The data we get from the VLBA is very high quality. We get the positions of the supermassive black holes to extremely good precision. Our limiting factor is the precision of the galaxy positions seen at other wavelengths that we use for comparison," Condon said. With new optical telescopes that will come on line in future years, such as the Large Synoptic Survey Telescope (LSST), he said, they will then have improved images that can be compared with the VLBA images. They hope that this will allow them to discover more objects like B3 1714+425. "And also maybe some of the binary supermassive black holes we originally sought," he said. Condon worked with Jeremy Darling of the University of Colorado, Yuri Kovalev of the Astro Space Center of the Lebedev Physical Institute in Moscow, and Leonid Petrov of the Astrogeo Center in Falls Church, Virginia. The scientists are reporting their findings in the Astrophysical Journal. The VLBA, dedicated in 1993, now is part of the Long Baseline Observatory. It uses ten, 25-meter-diameter dish antennas distributed from Hawaii to St. Croix in the Caribbean. It is operated from the NRAO's Domenici Science Operations Center in Socorro, NM. All ten antennas work together as a single telescope with the greatest resolving power available to astronomy. This unique capability has produced landmark contributions to numerous scientific fields, ranging from Earth tectonics, climate research, and spacecraft navigation, to cosmology. The Long Baseline Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.


News Article | November 3, 2016
Site: spaceref.com

Astronomers using the super-sharp radio vision of the Very Long Baseline Array (VLBA) have found the shredded remains of a galaxy that passed through a larger galaxy. This left only the smaller galaxy's nearly-naked supermassive black hole to emerge and speed away at more than 2,000 miles per second. The galaxies are part of a cluster of galaxies more than 2 billion light-years from Earth. The close encounter, millions of years ago, stripped the smaller galaxy of nearly all its stars and gas. What remains is its black hole and a small galactic remnant only about 3,000 light-years across. For comparison, our Milky Way Galaxy is approximately 100,000 light-years across. The discovery was made as part of a program to detect supermassive black holes, millions or billions of times more massive than the Sun, that are not at the centers of galaxies. Supermassive black holes reside at the centers of most galaxies. Large galaxies are thought to grow by devouring smaller companions. In such cases, the black holes of both are expected to orbit each other, eventually merging. "We were looking for orbiting pairs of supermassive black holes, with one offset from the center of a galaxy, as telltale evidence of a previous galaxy merger," said James Condon, of the National Radio Astronomy Observatory. "Instead, we found this black hole fleeing from the larger galaxy and leaving a trail of debris behind it," he added. "We've not seen anything like this before," Condon said. The astronomers began their quest by using the VLBA to make very high resolution images of more than 1,200 galaxies, previously identified by large-scale sky surveys done with infrared and radio telescopes. Their VLBA observations showed that the supermassive black holes of nearly all these galaxies were at the centers of the galaxies. However, one object, in a cluster of galaxies called ZwCl 8193, did not fit that pattern. Further studies showed that this object, called B3 1715+425, is a supermassive black hole surrounded by a galaxy much smaller and fainter than would be expected. In addition, this object is speeding away from the core of a much larger galaxy, leaving a wake of ionized gas behind it. The scientists concluded that B3 1715+425 is what has remained of a galaxy that passed through the larger galaxy and had most of its stars and gas stripped away by the encounter -- a "nearly naked" supermassive black hole. The speeding remnant, the scientists said, probably will lose more mass and cease forming new stars. "In a billion years or so, it probably will be invisible," Condon said. That means, he pointed out, that there could be many more such objects left over from earlier galactic encounters that astronomers can't detect. The scientists will keep looking, however. They're observing more objects, in a long-term project with the VLBA. Since their project is not time-critical, Condon explained, they use "filler time" when the telescope is not in use for other observations. "The data we get from the VLBA is very high quality. We get the positions of the supermassive black holes to extremely good precision. Our limiting factor is the precision of the galaxy positions seen at other wavelengths that we use for comparison," Condon said. With new optical telescopes that will come on line in future years, such as the Large Synoptic Survey Telescope (LSST), he said, they will then have improved images that can be compared with the VLBA images. They hope that this will allow them to discover more objects like B3 1714+425. "And also maybe some of the binary supermassive black holes we originally sought," he said. Condon worked with Jeremy Darling of the University of Colorado, Yuri Kovalev of the Astro Space Center of the Lebedev Physical Institute in Moscow, and Leonid Petrov of the Astrogeo Center in Falls Church, Virginia. The scientists are reporting their findings in the Astrophysical Journal. The VLBA, dedicated in 1993, now is part of the Long Baseline Observatory. It uses ten, 25-meter-diameter dish antennas distributed from Hawaii to St. Croix in the Caribbean. It is operated from the NRAO's Domenici Science Operations Center in Socorro, NM. All ten antennas work together as a single telescope with the greatest resolving power available to astronomy. This unique capability has produced landmark contributions to numerous scientific fields, ranging from Earth tectonics, climate research, and spacecraft navigation, to cosmology. Please follow SpaceRef on Twitter and Like us on Facebook.


News Article | February 21, 2017
Site: www.eurekalert.org

Our Galaxy's gravitational field limits the accuracy of astrometric observations of distant objects. This is most clearly appeared for objects that are visually located behind the central regions of the Galaxy and the Galactic plane, where the deviation can be up to several dozen microarcseconds. And, more importantly, the effect of this gravitational "noise" cannot be removed. This means that at a certain moment it will no longer be possible to improve the accuracy of determining the position of reference objects, which are used to define the coordinates of all other sources. The results of the study have been published in The Astrophysical Journal. It is widely known that our planet Earth and the Solar System itself are in the depths of the Milky Way, and it is through this galaxy that we look out onto the Universe. As it turns out, this fact is no small matter in astrophysical studies. How strong an effect can our Galaxy's gravitational field and its non-uniformity have on the accuracy of determining the coordinates of distant - extragalactic - objects? A group of Russian astrophysicists from the Astro Space Center (ASC) of P.N. Lebedev Physical Institute, the Space Research Institute of the RAS, MIPT, and the Max-Planck-Institut fuer Astrophysik (Germany) attempted to find an answer to this question. Proper motions, angular sizes, and trigonometric parallaxes (visible displacements) of celestial bodies, including stars, are the basic parameters for solving many astrophysical problems. These parameters are determined by astrometric techniques, and to calculate the position or radial velocity of star, for example, a coordinate system is needed that can be used to measure them against. All of the coordinate systems currently in use, including the International Celestial Reference Frame (ICRF), are based on the coordinates of several hundred "defining" extragalactic sources. Quasars and distant galaxies are ideal reference points for determining the celestial reference frame, as their angular movement is very small - around one-hundredth of a milliarcsecond (compared to the diameter of the Moon for example, which is a little more than 31 arcminutes). An arcsecond is an astronomical unit used to measure small angles, identical to the second of a plane angle. In the same way that an hour is divided as a time interval, the degree of an angle is divided into 60 minutes, and a minute into 60 seconds. Astrophysical instrumentation is developing rapidly and it is expected that the accuracy of radio interferometric observations will soon reach 1 microarcsecond, and the accuracy of optical observations - 10 microarcseconds per year. However, with this level of accuracy there comes a new challenge - the general theory of relativity, and in particular the deflection of a light beam when moving in a gravitational field, interfere with the observations. When a light beam from a distant source passes close to any object, it is slightly deflected by the gravity of the latter. This deviation is typically very small, but if the beam encounters several of these objects on its path, the deviation may be significant. In addition to this, as the objects are moving, the beam deflection angle changes in time and the source coordinates start to "jitter" around their true value. It is important to note that the coordinate "jittering" effect applies to all distant sources, including those that are used as reference points for different coordinate systems. "In attempting to improve the accuracy of implementing the coordinate reference system, we reach a limitation that cannot be bypassed by improving the accuracy of the detecting instruments. In fact, there is a gravitational noise, which makes it impossible to increase the accuracy of implementing a coordinate system above a certain level," says Alexander Lutovinov, a professor of the RAS, the head of laboratory of the Space Research Institute of the RAS, and a lecturer at MIPT. The researchers tried to estimate how much of an effect gravitational noise can have on observations. The calculations were based on modern models of the Galactic matter distribution. The two-dimensional "maps" of the entire sky were built for each model showing the standard deviation of the angular shifts in positions of distant sources with respect to their true positions. "Our calculations show that over a reasonable observational time of around ten years, the value of the standard deviation of shifts in positions of sources will be around 3 microarcseconds at high galactic latitudes, rising to several dozen microarcseconds toward the Galactic center," says Tatiana Larchenkova, a senior researcher at the ASC of P.N. Lebedev Physical Institute. "And this means that when the accuracy of measurements in absolute astrometry reaches microarcseconds, the "jittering" effect of reference source coordinates, which is caused by the Galaxy's non-stationary field, will need to be taken into account." The scientists investigated the properties of this gravitational noise that, in the future, will enable the noise to be excluded from observational data. They also demonstrated that the "jittering" effect of the coordinates can be partially compensated by using mathematical methods. The study was supported by Grant No. 14-22-00271 of the Russian Science Foundation.


News Article | February 23, 2017
Site: www.rdmag.com

Our Galaxy's gravitational field limits the accuracy of astrometric observations of distant objects. This is most clearly appeared for objects that are visually located behind the central regions of the Galaxy and the Galactic plane, where the deviation can be up to several dozen microarcseconds. And, more importantly, the effect of this gravitational "noise" cannot be removed. This means that at a certain moment it will no longer be possible to improve the accuracy of determining the position of reference objects, which are used to define the coordinates of all other sources. The results of the study have been published in The Astrophysical Journal. It is widely known that our planet Earth and the Solar System itself are in the depths of the Milky Way, and it is through this galaxy that we look out onto the Universe. As it turns out, this fact is no small matter in astrophysical studies. How strong an effect can our Galaxy's gravitational field and its non-uniformity have on the accuracy of determining the coordinates of distant - extragalactic - objects? A group of Russian astrophysicists from the Astro Space Center (ASC) of P.N. Lebedev Physical Institute, the Space Research Institute of the RAS, MIPT, and the Max-Planck-Institut fuer Astrophysik (Germany) attempted to find an answer to this question. Proper motions, angular sizes, and trigonometric parallaxes (visible displacements) of celestial bodies, including stars, are the basic parameters for solving many astrophysical problems. These parameters are determined by astrometric techniques, and to calculate the position or radial velocity of star, for example, a coordinate system is needed that can be used to measure them against. All of the coordinate systems currently in use, including the International Celestial Reference Frame (ICRF), are based on the coordinates of several hundred "defining" extragalactic sources. Quasars and distant galaxies are ideal reference points for determining the celestial reference frame, as their angular movement is very small - around one-hundredth of a milliarcsecond (compared to the diameter of the Moon for example, which is a little more than 31 arcminutes). An arcsecond is an astronomical unit used to measure small angles, identical to the second of a plane angle. In the same way that an hour is divided as a time interval, the degree of an angle is divided into 60 minutes, and a minute into 60 seconds. Astrophysical instrumentation is developing rapidly and it is expected that the accuracy of radio interferometric observations will soon reach 1 microarcsecond, and the accuracy of optical observations - 10 microarcseconds per year. However, with this level of accuracy there comes a new challenge - the general theory of relativity, and in particular the deflection of a light beam when moving in a gravitational field, interfere with the observations. When a light beam from a distant source passes close to any object, it is slightly deflected by the gravity of the latter. This deviation is typically very small, but if the beam encounters several of these objects on its path, the deviation may be significant. In addition to this, as the objects are moving, the beam deflection angle changes in time and the source coordinates start to "jitter" around their true value. It is important to note that the coordinate "jittering" effect applies to all distant sources, including those that are used as reference points for different coordinate systems. "In attempting to improve the accuracy of implementing the coordinate reference system, we reach a limitation that cannot be bypassed by improving the accuracy of the detecting instruments. In fact, there is a gravitational noise, which makes it impossible to increase the accuracy of implementing a coordinate system above a certain level," says Alexander Lutovinov, a professor of the RAS, the head of laboratory of the Space Research Institute of the RAS, and a lecturer at MIPT. The researchers tried to estimate how much of an effect gravitational noise can have on observations. The calculations were based on modern models of the Galactic matter distribution. The two-dimensional "maps" of the entire sky were built for each model showing the standard deviation of the angular shifts in positions of distant sources with respect to their true positions. "Our calculations show that over a reasonable observational time of around ten years, the value of the standard deviation of shifts in positions of sources will be around 3 microarcseconds at high galactic latitudes, rising to several dozen microarcseconds toward the Galactic center," says Tatiana Larchenkova, a senior researcher at the ASC of P.N. Lebedev Physical Institute. "And this means that when the accuracy of measurements in absolute astrometry reaches microarcseconds, the "jittering" effect of reference source coordinates, which is caused by the Galaxy's non-stationary field, will need to be taken into account." The scientists investigated the properties of this gravitational noise that, in the future, will enable the noise to be excluded from observational data. They also demonstrated that the "jittering" effect of the coordinates can be partially compensated by using mathematical methods.


Our galaxy's gravitational field limits the accuracy of astrometric observations of distant objects. This is most apparent for objects that are obscured behind the central regions of the galaxy and the galactic plane, where the deviation can be up to several dozen microarcseconds. And more importantly, the effect of this gravitational "noise" cannot be removed. This means that beyond a certain point, it will no longer be possible to improve the accuracy of determining the position of reference objects that are used to define the coordinates of all other sources. The results of the study have been published in the Astrophysical Journal. It is widely known that Earth and the solar system are embedded within the Milky Way, through which we look out to the universe. As it turns out, this fact is no small matter in astrophysical studies. How strong an effect can our galaxy's gravitational field and its non-uniformity have on the accuracy of determining the coordinates of distant extragalactic objects? A group of Russian astrophysicists from the Astro Space Center (ASC) of P.N. Lebedev Physical Institute, the Space Research Institute of the RAS, MIPT, and the Max-Planck-Institut fuer Astrophysik (Germany) attempted to find an answer to this question. Proper motions, angular sizes, and trigonometric parallaxes (visible displacements) of celestial bodies, including stars, are the basic parameters for solving many astrophysical problems. These parameters are determined by astrometric techniques. To calculate the position or radial velocity of star, for example, a coordinate system is needed that can be used to measure them against. All of the coordinate systems currently in use, including the International Celestial Reference Frame (ICRF), are based on the coordinates of several hundred "defining" extragalactic sources. Quasars and distant galaxies are ideal reference points for determining the celestial reference frame, as their angular movement is very small— around one-hundredth of a milliarcsecond (compared to the diameter of the moon, for example, which is a little more than 31 arcminutes). Astrophysical instrumentation is advancing rapidly, and it is expected that the accuracy of radio interferometric observations will soon reach 1 microarcsecond, and the accuracy of optical observations 10 microarcseconds per year. However, with this level of accuracy, there comes a new challenge—the general theory of relativity, and in particular the deflection of a light beam when moving in a gravitational field, interfere with the observations. When a light beam from a distant source passes close to any object, it is slightly deflected by the gravity of the latter. This deviation is typically very small, but if the beam encounters several of these objects on its path, the deviation may be significant. In addition, as the objects are moving, the beam deflection angle changes in time and the source coordinates start to "jitter" around their true value. It is important to note that the coordinate "jittering" effect applies to all distant sources, including those that are used as reference points for different coordinate systems. "In attempting to improve the accuracy of implementing the coordinate reference system, we reach a limitation that cannot be bypassed by improving the accuracy of the detecting instruments. In fact, there is gravitational noise, which makes it impossible to increase the accuracy of implementing a coordinate system above a certain level," says Alexander Lutovinov, a professor of the RAS, the head of laboratory of the Space Research Institute of the RAS, and a lecturer at MIPT. The researchers tried to estimate how much of an effect gravitational noise can have on observations. The calculations were based on modern models of the galactic matter distribution. The two-dimensional "maps" of the entire sky were built for each model showing the standard deviation of the angular shifts in positions of distant sources with respect to their true positions. "Our calculations show that over a reasonable observational time of around ten years, the value of the standard deviation of shifts in positions of sources will be around three microarcseconds at high galactic latitudes, rising to several dozen microarcseconds toward the galactic center," says Tatiana Larchenkova, a senior researcher at the ASC of P.N. Lebedev Physical Institute. "And this means that when the accuracy of measurements in absolute astrometry reaches microarcseconds, the "jittering" effect of reference source coordinates, which is caused by the galaxy's non-stationary field, will need to be taken into account." The scientists investigated the properties of this gravitational noise, which, in the future, will enable the noise to be excluded from observational data. They also demonstrated that the "jittering" effect of the coordinates can be partially compensated by using mathematical methods. Explore further: Missing stars in the solar neighbourhood reveal the sun's speed and distance to the centre of the Milky Way galaxy More information: Tatiana I. Larchenkova et al. INFLUENCE OF THE GALACTIC GRAVITATIONAL FIELD ON THE POSITIONAL ACCURACY OF EXTRAGALACTIC SOURCES, The Astrophysical Journal (2017). DOI: 10.3847/1538-4357/835/1/51


News Article | January 26, 2016
Site: phys.org

Using an orbiting radio-astronomy satellite combined with 15 ground-based radio telescopes, astronomers have made the highest-resolution, or most-detailed, astronomical image yet, revealing new insights about a gorging black hole in a galaxy 900 million light-years from Earth. The scientists combined signals from the Spektr-R satellite of the RadioAstron mission with those from radio telescopes throughout Europe and nine antennas of the National Science Foundation's Very Long Baseline Array (VLBA). The result was an image with the resolving power of a telescope about 62,500 miles wide, or almost eight times the diameter of the Earth. The image shows radio emission coming from a jet of particles accelerated to speeds nearly that of light by the gravitational power of a supermassive black hole at the core of a galaxy called BL Lacertae. The jet shown by this image would fit within the outer extent of our solar system, marked by the Oort Cloud of cometary objects that reside far beyond the familiar planets. The image shows detail roughly equivalent to seeing a 50-cent coin on the Moon. The image appears elongated because the distance between the satellite and the ground telescopes is so much greater than that among the ground telescopes themselves, providing greater resolving power in one direction. In this version, resolution in the orthogonal direction is exaggerated to compensate. The satellite project is led by the Astro Space Center in Moscow, and the data from all 15 telescopes were combined at a facility of the Max Planck Institute for Radio Astronomy in Bonn, Germany. The scientists are reporting on their work in the Astrophysical Journal. Explore further: The birth of a telescope 30 times larger than Earth More information: "Probing the Innermost Regions of AGN Jets and Their Magnetic Fields with RadioAstron. I. Imaging BL Lacertae at 21 Microarcsecond Resolution," José L. Gómez & Andrei P. Lobanov et al., 2016 Feb. 1, Astrophysical Journal iopscience.iop.org/article/10.3847/0004-637X/817/2/96 , Arxiv: arxiv.org/abs/1512.04690


Voronkov M.A.,CSIRO | Voronkov M.A.,Astro Space Center | Caswell J.L.,CSIRO | Britton T.R.,CSIRO | And 4 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2010

The Australia Telescope Compact Array (ATCA) has been used to map class I methanol masers at 36 and 44GHz in G309.38-0.13. Maser spots are found at nine locations in an area of 50 × 30 arcsec2, with both transitions reliably detected at only two locations. The brightest spot is associated with shocked gas traced by 4.5-μm emission. The data allowed us to make a serendipitous discovery of a high-velocity 36-GHz spectral feature, which is blueshifted by about 30kms-1 from the peak velocity at this frequency, but spatially located close to (within a few arcseconds of) the brightest maser spot. We interpret this as indicating an outflow parallel to the line of sight. Such a high-velocity spread of maser features, which has not been previously reported in the class I methanol masers associated with a single molecular cloud, suggests that the outflow most likely interacts with a moving parcel of gas. © 2010 CSIRO. Journal compilation © 2010 RAS.


Voronkov M.A.,CSIRO | Voronkov M.A.,Astro Space Center | Caswell J.L.,CSIRO | Ellingsen S.P.,University of Tasmania | Sobolev A.M.,Ural Federal University
Monthly Notices of the Royal Astronomical Society | Year: 2010

The Australia Telescope Compact Array has been used to make the first extensive search for the class I methanol masers at 9.9 GHz. In total, 48 regions of high-mass star formation were observed. In addition to masers in W33-Met (G12.80. -0.19) and G343.12. -0.06 (IRAS 16547. -4247) which have already been reported in the literature, two new 9.9-GHz masers have been found towards G331.13. -0.24 and G19.61. -0.23. We have determined absolute positions (accurate to roughly a second of arc) for all the detected masers and suggest that some class I masers may be associated with shocks driven into molecular clouds by expanding H ii regions. Our observations also imply that the evolutionary stage of a high-mass star-forming region when the class I masers are present can outlast the stage when the class II masers at 6.7-GHz are detectable, and overlaps significantly with the stage when OH masers are active. © 2010 CSIRO. Journal compilation © 2010 RAS.


Kalinina N.D.,Ural Federal University | Sobolev A.M.,Ural Federal University | Kalenskii S.V.,Astro Space Center
New Astronomy | Year: 2010

Results of a spectral survey of molecular cores NGC 6334I and NGC 6334I(N) in a number of spectral intervals with widths of about 1000 MHz are presented. Observations were carried out with the SEST radiotelescope. Number of the intervals for NGC 6334I was 11. 209 spectral features were detected towards molecular core NGC 6334I, out of which 203 features were assigned to 25 species. Number of the intervals for NGC 6334I(N) was 6. They represent a subset of the intervals used for the NGC 6334I. The spectrum of NGC 6334I(N) appears to be considerably more poor with the features: 63 features were detected, out of which 55 were assigned to 13 species. Catalogues of assigned features for both sources are presented. They contain the notation of corresponding molecular transition, frequency, and the following observational data: integrated intensity, Vlsr velocity, FWHM and antenna temperature. © 2010 Elsevier B.V. All rights reserved.

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