Astronomical Data Analysis Software and Systems XXIX
Astronomical Society of the Pacific Conference Series eBooks, 2020
... Publication: Astronomical Data Analysis Software and Systems IX, ASP Conference Proceedings, ... more ... Publication: Astronomical Data Analysis Software and Systems IX, ASP Conference Proceedings, Vol. 216, edited by Nadine Manset, Christian Veillet, and Dennis Crabtree. Astronomical Society of the Pacific, ISBN 1-58381-047-1, 2000. Publication Date: 00/2000. Origin: ASP. ...
The distributions of interstellar dust and gas in the Galaxy are compared. Radiotelescopes tuned ... more The distributions of interstellar dust and gas in the Galaxy are compared. Radiotelescopes tuned to CO signatures have been used to map the distribution of cold molecular gas clumped in the inner annulus of the Galaxy. H I observations have provided the distribution of cool atomic gas which is diffuse throughout the Galaxy but locally exhibits alterations due to mechanical and radiative influences. IRAS maps of 60 and 100 micron emissions are provided to illustrate the known dust distributions, which superficially resemble the H I distributions. The steps necessary to eliminate the influence of the Zodiacal dust on the IRAS maps are summarized. The 100 micron dust is distributed over a larger fraction of interstellar space than are the cold molecular clouds, and apparently form into clumpy regions at higher latitudes. However, the clumps may simply be an artifact of blending along the line of sight and may be resolved by observations at different wavelengths.
The current status of astrometry in Astro-WISE is explored. This includes the underlying mechanis... more The current status of astrometry in Astro-WISE is explored. This includes the underlying mechanisms, procedures, performance, and accuracies of both the local and the global astrometric solution, as well as the improvement from the local to the global solution. Using all currently Astro-WISE processed data from the WFI instrument on the MPG/ESO 2.2m telescope (24512 frames, more than 3000 exposures), we show that the overall accuracies are consistent with and due to the precision of the USNO-A2.0 reference catalog (0.3 arcsec RMS and 1 arcsec systematic) for the local solution and are approximately 0.04 arcsec for the global solution. In addition, it is found that the precision of the underlying software (SExtractor, LDAC, SWarp) in extracting sources, applying solutions, and regridding frames to 0.200 arcsec per pixel is of the order 0.02 arcsec RMS. The performance of the local solution has a virtually 100% success rate with respect to the underlying software, a 98.0% success rate...
Aims. MASCARA and bRing are photometric surveys designed to detect variability caused by exoplane... more Aims. MASCARA and bRing are photometric surveys designed to detect variability caused by exoplanets in stars with mV < 8.4. Such variability signals are typically small and require an accurate calibration algorithm, tailored to the survey, in order to be detected. This paper presents the methods developed to calibrate the raw photometry of the MASCARA and bRing stations and characterizes the performance of the methods and instruments. Methods. For the primary calibration, a modified version of the coarse decorrelation algorithm is used, which corrects for the extinction due to the earth’s atmosphere, the camera transmission, and intrapixel variations. Residual trends are removed from the light curves of individual stars using empirical secondary calibration methods. In order to optimize these methods, as well as characterize the performance of the instruments, transit signals were injected in the data. Results. After optimal calibration an RMS scatter of 10 mmag at mV ~ 7.5 is ac...
The Morphology of Cool, Diffuse Gas and Dust in the Galaxy
The Galaxy, 1987
The density of interstellar nucleons in our Galaxy is dominated by neutral gas at temperatures ra... more The density of interstellar nucleons in our Galaxy is dominated by neutral gas at temperatures ranging from a few K to a few hundred K. At the lower end of this temperature range, between a few K and about 30K, the gas is almost entirely in the form of molecular hydrogen, residing in compressed clumps whose distribution is largely confined to an annulus in the inner Galaxy. This gas is most effectively traced by observations of carbon monoxide, which serves as a surrogate for the generally unobservable H2. At the warmer temperatures, between a few tens and a few hundred degrees, most of the gas is in the form of atomic hydrogen. The atomic hydrogen is much more diffusely distributed than the molecular gas, and is distributed over a much wider Galactic extent. The total mass of H2 in the Galaxy is about 109 M⊙; the total amount of HI is about 4 x 109 M⊙. Some 5 percent of the visible total mass in the Galaxy resides in the cool interstellar medium. The contribution to the overall mass budget by gaseous components at higher temperatures is much less. The high temperature material is of course important to considerations of the energetics of the interstellar medium, but the cool material is also important in this regard: it not only dominates the mass budget, but because it fills much of the interstellar volume it participates in most aspects of the dynamics and evolution of the medium. Estimates of the volume filling factor of atomic hydrogen range from about 20 percent to more than 80 percent. A much smaller portion of the interstellar volume is filled by clouds of molecular gas.
The mapping discussed in this paper is based on observations obtained from the 21-cm emission lin... more The mapping discussed in this paper is based on observations obtained from the 21-cm emission line of neutral atomic hydrogen. We will give an overview of the existing large surveys and present a homogeneous datacube that contains the most important surveys. This datacube was created by regridding the original observations, for the surveys included, onto a common denominator grid. Presenting a three dimensional dataset of intensities in one single image is impossible, therefore we made a film that displays in a time sequence a set of cuts (position-velocity maps) through the datacube. The advantage of showing the third coordinate in time is that the eye can now catch continuities in this coordinate that were previously hidden in the data. I.
Comparative Global Properties of Interstellar Dust and Gas in the Galaxy
Saas-Fee Advanced Courses
The morphology of the galactic infrared dust emission observed with IRAS is compared here with th... more The morphology of the galactic infrared dust emission observed with IRAS is compared here with that of the neutral gas component on scales ranging from kiloparsecs down to those corresponding to the resolution limits of the surveys. Correlations are particularly strong for the 100-μm emission at latitudes |b| &gt; 5°. After subtraction of the contaminating zodiacal emission, the morphologies at
During a regular night dedicated to the survey, less than 10 photometric standard stars in each b... more During a regular night dedicated to the survey, less than 10 photometric standard stars in each band can be observed. This is enough to check the photometric quality of the night but not to define the DENIS photometric system. For that, 1 or 2 nights per month are dedicated to photometry in order to determine accurately the atmospheric extinction coefficients, the zero-points, and the transformation coefficients between the DENIS instrumental system and other photometric systems. In this paper, the main steps of the DENIS photometric calibration (development of the standard star catalogue, observing strategy, data processing, etc.) are reviewed and preliminary results based on a few calibration nights are presented.
A catalog of H I holes in M33 has been compiled, and the characteristics of the H I hole ensemble... more A catalog of H I holes in M33 has been compiled, and the characteristics of the H I hole ensemble are reported. The observed holes are correlated with other objects known to influence the physical properties of the surrounding ISM. Small holes correlate well with OB associations and to a lesser extent with H II regions. The giant H II regions coincide with small, high-contrast H I holes of similar morphology. Large holes show an anticorrelation in the sense that the H II regions and OB associations lie on the edges. The diameters of the holes range from the survey resolution limit of 40 pc to 1 kpc. The swept-up mass ranges from 1000 to 10 million solar.
The distributions of interstellar dust and gas in the Galaxy are compared. Radiotelescopes tuned ... more The distributions of interstellar dust and gas in the Galaxy are compared. Radiotelescopes tuned to CO signatures have been used to map the distribution of cold molecular gas clumped in the inner annulus of the Galaxy. H I observations have provided the distribution of cool atomic gas which is diffuse throughout the Galaxy but locally exhibits alterations due to mechanical and radiative influences. IRAS maps of 60 and 100 micron emissions are provided to illustrate the known dust distributions, which superficially resemble the H I distributions. The steps necessary to eliminate the influence of the Zodiacal dust on the IRAS maps are summarized. The 100 micron dust is distributed over a larger fraction of interstellar space than are the cold molecular clouds, and apparently form into clumpy regions at higher latitudes. However, the clumps may simply be an artifact of blending along the line of sight and may be resolved by observations at different wavelengths.
The kinematic structure of cirrus features was examined in seven cirrus fields by identifying the... more The kinematic structure of cirrus features was examined in seven cirrus fields by identifying the velocity intervals in the 21-cm line emission. The velocities of the H I structures associated with the infrared cirrus span a large range. Cirrus features are sometimes superpositions of kinematically distinct components which can be separated on the basis of kinematic information. The results of the analysis suggest that anomalous velocities are common among cirrus features and that some acceleration mechanism is an important aspect of the general cirrus phenomenon.
Herschel-HIFI observations of water in the low-mass star-forming object L1448-MM, known for its p... more Herschel-HIFI observations of water in the low-mass star-forming object L1448-MM, known for its prominent outflow, are presented, as obtained within the "Water in star-forming regions with Herschel" (WISH) key programme. Six H 16 2 O lines are targeted and detected (E up /k B ∼ 50-250 K), as is CO J = 10-9 (E up /k B ∼ 305 K), and tentatively H 18 2 O 1 10-1 01 at 548 GHz. All lines show strong emission in the "bullets" at | | > 50 km s −1 from the source velocity, in addition to a broad, central component and narrow absorption. The bullets are seen much more prominently in H 2 O than in CO with respect to the central component, and show little variation with excitation in H 2 O profile shape. Excitation conditions in the bullets derived from CO lines imply a temperature >150 K and density >10 5 cm −3 , similar to that of the broad component. The H 2 O/CO abundance ratio is similar in the "bullets" and the broad component, ∼0.05-1.0, in spite of their different origins in the molecular jet and the interaction between the outflow and the envelope. The high H 2 O abundance indicates that the bullets are H 2 rich. The H 2 O cooling in the "bullets" and the broad component is similar and higher than the CO cooling in the same components. These data illustrate the power of Herschel-HIFI to disentangle different dynamical components in low-mass star-forming objects and determine their excitation and chemical conditions.
Astronomy and Astrophysics Supplement Series, 2000
An absolute calibration of the DENIS photometric system is presented. It includes the determinati... more An absolute calibration of the DENIS photometric system is presented. It includes the determination of the overall transmission profiles in the 3 bands, namely i, J and K s , combining contributions from atmosphere, telescope mirrors, instrument lenses and dichroics, filters, and detectors. From these normalized profiles, isophotal and effective wavelengths are computed, using the same synthetic Vega spectrum as that used to support the absolute calibration of many other ground-based and spaceborne photometric systems. Flux densities at zero magnitude are derived and integrated to give in-band fluxes, which are used to compute theoretical zero-points and compare them to observed ones, yielding estimates of the overall throughput of the whole system.
An investigation of the micro-variations of highly luminous OBA type stars. I
Astronomy and Astrophysics Supplement Series, Aug 1, 1985
AUGUST 1985, PAGE 213 ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES Astron. Astrophys. Suppi. Ser. 6... more AUGUST 1985, PAGE 213 ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES Astron. Astrophys. Suppi. Ser. 61, 213-220 (1985) An investigation of the micro-variations of highly luminous OBA type stars. I (*) AM van Genderen (1), P. Alphenaar (1), MDP van der Bij (1), ER Deul (1), W. van Driel (2), GM van Heerde (`), L. de Lange (`), F. van Leeuwen (3), JJM Meys (1), J. Oppe (1), PS The (4) and MJJ Wiertz (1) (**) (1) Leiden Observatory, Postbus 9513, 2300 RA Leiden, The Netherlands (2) Kapteyn Astronomical Institute, Postbus 800, ...
Astronomical Data Analysis Software and Systems XXIX
Astronomical Society of the Pacific Conference Series eBooks, 2020
... Publication: Astronomical Data Analysis Software and Systems IX, ASP Conference Proceedings, ... more ... Publication: Astronomical Data Analysis Software and Systems IX, ASP Conference Proceedings, Vol. 216, edited by Nadine Manset, Christian Veillet, and Dennis Crabtree. Astronomical Society of the Pacific, ISBN 1-58381-047-1, 2000. Publication Date: 00/2000. Origin: ASP. ...
The distributions of interstellar dust and gas in the Galaxy are compared. Radiotelescopes tuned ... more The distributions of interstellar dust and gas in the Galaxy are compared. Radiotelescopes tuned to CO signatures have been used to map the distribution of cold molecular gas clumped in the inner annulus of the Galaxy. H I observations have provided the distribution of cool atomic gas which is diffuse throughout the Galaxy but locally exhibits alterations due to mechanical and radiative influences. IRAS maps of 60 and 100 micron emissions are provided to illustrate the known dust distributions, which superficially resemble the H I distributions. The steps necessary to eliminate the influence of the Zodiacal dust on the IRAS maps are summarized. The 100 micron dust is distributed over a larger fraction of interstellar space than are the cold molecular clouds, and apparently form into clumpy regions at higher latitudes. However, the clumps may simply be an artifact of blending along the line of sight and may be resolved by observations at different wavelengths.
The current status of astrometry in Astro-WISE is explored. This includes the underlying mechanis... more The current status of astrometry in Astro-WISE is explored. This includes the underlying mechanisms, procedures, performance, and accuracies of both the local and the global astrometric solution, as well as the improvement from the local to the global solution. Using all currently Astro-WISE processed data from the WFI instrument on the MPG/ESO 2.2m telescope (24512 frames, more than 3000 exposures), we show that the overall accuracies are consistent with and due to the precision of the USNO-A2.0 reference catalog (0.3 arcsec RMS and 1 arcsec systematic) for the local solution and are approximately 0.04 arcsec for the global solution. In addition, it is found that the precision of the underlying software (SExtractor, LDAC, SWarp) in extracting sources, applying solutions, and regridding frames to 0.200 arcsec per pixel is of the order 0.02 arcsec RMS. The performance of the local solution has a virtually 100% success rate with respect to the underlying software, a 98.0% success rate...
Aims. MASCARA and bRing are photometric surveys designed to detect variability caused by exoplane... more Aims. MASCARA and bRing are photometric surveys designed to detect variability caused by exoplanets in stars with mV < 8.4. Such variability signals are typically small and require an accurate calibration algorithm, tailored to the survey, in order to be detected. This paper presents the methods developed to calibrate the raw photometry of the MASCARA and bRing stations and characterizes the performance of the methods and instruments. Methods. For the primary calibration, a modified version of the coarse decorrelation algorithm is used, which corrects for the extinction due to the earth’s atmosphere, the camera transmission, and intrapixel variations. Residual trends are removed from the light curves of individual stars using empirical secondary calibration methods. In order to optimize these methods, as well as characterize the performance of the instruments, transit signals were injected in the data. Results. After optimal calibration an RMS scatter of 10 mmag at mV ~ 7.5 is ac...
The Morphology of Cool, Diffuse Gas and Dust in the Galaxy
The Galaxy, 1987
The density of interstellar nucleons in our Galaxy is dominated by neutral gas at temperatures ra... more The density of interstellar nucleons in our Galaxy is dominated by neutral gas at temperatures ranging from a few K to a few hundred K. At the lower end of this temperature range, between a few K and about 30K, the gas is almost entirely in the form of molecular hydrogen, residing in compressed clumps whose distribution is largely confined to an annulus in the inner Galaxy. This gas is most effectively traced by observations of carbon monoxide, which serves as a surrogate for the generally unobservable H2. At the warmer temperatures, between a few tens and a few hundred degrees, most of the gas is in the form of atomic hydrogen. The atomic hydrogen is much more diffusely distributed than the molecular gas, and is distributed over a much wider Galactic extent. The total mass of H2 in the Galaxy is about 109 M⊙; the total amount of HI is about 4 x 109 M⊙. Some 5 percent of the visible total mass in the Galaxy resides in the cool interstellar medium. The contribution to the overall mass budget by gaseous components at higher temperatures is much less. The high temperature material is of course important to considerations of the energetics of the interstellar medium, but the cool material is also important in this regard: it not only dominates the mass budget, but because it fills much of the interstellar volume it participates in most aspects of the dynamics and evolution of the medium. Estimates of the volume filling factor of atomic hydrogen range from about 20 percent to more than 80 percent. A much smaller portion of the interstellar volume is filled by clouds of molecular gas.
The mapping discussed in this paper is based on observations obtained from the 21-cm emission lin... more The mapping discussed in this paper is based on observations obtained from the 21-cm emission line of neutral atomic hydrogen. We will give an overview of the existing large surveys and present a homogeneous datacube that contains the most important surveys. This datacube was created by regridding the original observations, for the surveys included, onto a common denominator grid. Presenting a three dimensional dataset of intensities in one single image is impossible, therefore we made a film that displays in a time sequence a set of cuts (position-velocity maps) through the datacube. The advantage of showing the third coordinate in time is that the eye can now catch continuities in this coordinate that were previously hidden in the data. I.
Comparative Global Properties of Interstellar Dust and Gas in the Galaxy
Saas-Fee Advanced Courses
The morphology of the galactic infrared dust emission observed with IRAS is compared here with th... more The morphology of the galactic infrared dust emission observed with IRAS is compared here with that of the neutral gas component on scales ranging from kiloparsecs down to those corresponding to the resolution limits of the surveys. Correlations are particularly strong for the 100-μm emission at latitudes |b| &gt; 5°. After subtraction of the contaminating zodiacal emission, the morphologies at
During a regular night dedicated to the survey, less than 10 photometric standard stars in each b... more During a regular night dedicated to the survey, less than 10 photometric standard stars in each band can be observed. This is enough to check the photometric quality of the night but not to define the DENIS photometric system. For that, 1 or 2 nights per month are dedicated to photometry in order to determine accurately the atmospheric extinction coefficients, the zero-points, and the transformation coefficients between the DENIS instrumental system and other photometric systems. In this paper, the main steps of the DENIS photometric calibration (development of the standard star catalogue, observing strategy, data processing, etc.) are reviewed and preliminary results based on a few calibration nights are presented.
A catalog of H I holes in M33 has been compiled, and the characteristics of the H I hole ensemble... more A catalog of H I holes in M33 has been compiled, and the characteristics of the H I hole ensemble are reported. The observed holes are correlated with other objects known to influence the physical properties of the surrounding ISM. Small holes correlate well with OB associations and to a lesser extent with H II regions. The giant H II regions coincide with small, high-contrast H I holes of similar morphology. Large holes show an anticorrelation in the sense that the H II regions and OB associations lie on the edges. The diameters of the holes range from the survey resolution limit of 40 pc to 1 kpc. The swept-up mass ranges from 1000 to 10 million solar.
The distributions of interstellar dust and gas in the Galaxy are compared. Radiotelescopes tuned ... more The distributions of interstellar dust and gas in the Galaxy are compared. Radiotelescopes tuned to CO signatures have been used to map the distribution of cold molecular gas clumped in the inner annulus of the Galaxy. H I observations have provided the distribution of cool atomic gas which is diffuse throughout the Galaxy but locally exhibits alterations due to mechanical and radiative influences. IRAS maps of 60 and 100 micron emissions are provided to illustrate the known dust distributions, which superficially resemble the H I distributions. The steps necessary to eliminate the influence of the Zodiacal dust on the IRAS maps are summarized. The 100 micron dust is distributed over a larger fraction of interstellar space than are the cold molecular clouds, and apparently form into clumpy regions at higher latitudes. However, the clumps may simply be an artifact of blending along the line of sight and may be resolved by observations at different wavelengths.
The kinematic structure of cirrus features was examined in seven cirrus fields by identifying the... more The kinematic structure of cirrus features was examined in seven cirrus fields by identifying the velocity intervals in the 21-cm line emission. The velocities of the H I structures associated with the infrared cirrus span a large range. Cirrus features are sometimes superpositions of kinematically distinct components which can be separated on the basis of kinematic information. The results of the analysis suggest that anomalous velocities are common among cirrus features and that some acceleration mechanism is an important aspect of the general cirrus phenomenon.
Herschel-HIFI observations of water in the low-mass star-forming object L1448-MM, known for its p... more Herschel-HIFI observations of water in the low-mass star-forming object L1448-MM, known for its prominent outflow, are presented, as obtained within the "Water in star-forming regions with Herschel" (WISH) key programme. Six H 16 2 O lines are targeted and detected (E up /k B ∼ 50-250 K), as is CO J = 10-9 (E up /k B ∼ 305 K), and tentatively H 18 2 O 1 10-1 01 at 548 GHz. All lines show strong emission in the "bullets" at | | > 50 km s −1 from the source velocity, in addition to a broad, central component and narrow absorption. The bullets are seen much more prominently in H 2 O than in CO with respect to the central component, and show little variation with excitation in H 2 O profile shape. Excitation conditions in the bullets derived from CO lines imply a temperature >150 K and density >10 5 cm −3 , similar to that of the broad component. The H 2 O/CO abundance ratio is similar in the "bullets" and the broad component, ∼0.05-1.0, in spite of their different origins in the molecular jet and the interaction between the outflow and the envelope. The high H 2 O abundance indicates that the bullets are H 2 rich. The H 2 O cooling in the "bullets" and the broad component is similar and higher than the CO cooling in the same components. These data illustrate the power of Herschel-HIFI to disentangle different dynamical components in low-mass star-forming objects and determine their excitation and chemical conditions.
Astronomy and Astrophysics Supplement Series, 2000
An absolute calibration of the DENIS photometric system is presented. It includes the determinati... more An absolute calibration of the DENIS photometric system is presented. It includes the determination of the overall transmission profiles in the 3 bands, namely i, J and K s , combining contributions from atmosphere, telescope mirrors, instrument lenses and dichroics, filters, and detectors. From these normalized profiles, isophotal and effective wavelengths are computed, using the same synthetic Vega spectrum as that used to support the absolute calibration of many other ground-based and spaceborne photometric systems. Flux densities at zero magnitude are derived and integrated to give in-band fluxes, which are used to compute theoretical zero-points and compare them to observed ones, yielding estimates of the overall throughput of the whole system.
An investigation of the micro-variations of highly luminous OBA type stars. I
Astronomy and Astrophysics Supplement Series, Aug 1, 1985
AUGUST 1985, PAGE 213 ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES Astron. Astrophys. Suppi. Ser. 6... more AUGUST 1985, PAGE 213 ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES Astron. Astrophys. Suppi. Ser. 61, 213-220 (1985) An investigation of the micro-variations of highly luminous OBA type stars. I (*) AM van Genderen (1), P. Alphenaar (1), MDP van der Bij (1), ER Deul (1), W. van Driel (2), GM van Heerde (`), L. de Lange (`), F. van Leeuwen (3), JJM Meys (1), J. Oppe (1), PS The (4) and MJJ Wiertz (1) (**) (1) Leiden Observatory, Postbus 9513, 2300 RA Leiden, The Netherlands (2) Kapteyn Astronomical Institute, Postbus 800, ...
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