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101. Probing the Discs of Herbig Ae/Be Stars at Terrestrial Orbits

Author

Abuter, R., Accardo, M., Adler, T., Amorim, A., Anugu, N., Ávila, G., Bauböck, M., Benisty, M., Berger, J.-P., Bestenlehner, J. M., Beust, H., Blind, N., Bonnefoy, M., BONNET, H., Bourget, P., Bouvier, J., Brandner, W., Brast, R., Buron, A., Burtscher, L., Cantalloube, F., Caratti O Garatti, A., Caselli, P., Cassaing, F., Chapron, F., Charnay, B., Choquet, E., Clénet, Y., Collin, C., Coudé Du Foresto, V., Davies, R., Deen, C., Delplancke-Ströbele, F., Dembet, R., Derie, F., de Wit, W.-J., Dexter, J., De Zeeuw, T., Dougados, C., Dubus, G., Duvert, G., Ebert, M., Eckart, A., Eisenhauer, F., Esselborn, M., Eupen, F., Fédou, P., Ferreira, M. C., Finger, G., Förster Schreiber, N. M., Gao, F., García Dabó, C. E., Garcia Lopez, R., Garcia, P. J. V., Gendron, É., Genzel, R., Gerhard, O., Gil, J. P., Gillessen, S., Gonté, F., Gordo, P., Gratadour, D., Greenbaum, A., Grellmann, R., Grözinger, U., Guajardo, P., Guieu, S., Habibi, M., Haguenauer, P., Hans, O., Haubois, X., Haug, M., Haußmann, F., Henning, T., Hippler, S., Hönig, S. F., Horrobin, M., Huber, A., Hubert, Z., Hubin, N., Hummel, C. A., Jakob, G., Janssen, A., Jimenez Rosales, A., Jochum, L., Jocou, L., Kammerer, J., Karl, M., Kaufer, A., Kellner, S., Kendrew, S., Kern, L., Kervella, P., Kiekebusch, M., Kishimoto, M., Klarmann, L., Klein, R., Köhler, R., Kok, Y., Kolb, J., Koutoulaki, M., Kulas, M., Labadie, L., Lacour, S., Lagrange, A.-M., Lapeyrère, V., Laun, W., Lazareff, B., Le Bouquin, J.-B., Léna, P., Lenzen, R., Lévêque, S., Lin, C.-C., Lippa, M., Lutz, D., Magnard, Y., Maire, A.-L., Mehrgan, L., Mérand, A., Millour, F., Mollière, P., Moulin, T., Müller, A., Müller, E., Müller, F., Netzer, H., Neumann, U., Nowak, M., Oberti, S., Ott, T., Pallanca, L., Panduro, J., Pasquini, L., Paumard, T., Percheron, I., Perraut, K., Perrin, G., Peterson, B. M., Petrucci, P.-O., Pflüger, A., Pfuhl, O., Phan Duc, T., Pineda, J. E., Plewa, P. m., Popovic, D., Pott, J.-U., Prieto, A., Pueyo, L., Rabien, S., Ramírez, A., Ramos, J. R., Rau, C., Ray, T., Riquelme, M., Rodríguez-Coira, G., Rohloff, R.-R., Rouan, D., Rousset, G., Sanchez-Bermudez, J., Schartmann, M., Scheithauer, S., Schöller, M., Schuhler, N., Segura-Cox, D., Shangguan, J., Shimizu, T. T., Spyromilio, J., Sternberg, A., Stock, M. R., Straub, O., Straubmeier, C., Sturm, E., Suárez Valles, M., Tacconi, L. J., Thi, W.-F., Tristram, K. R. W., Valenzuela, J. J., Van Boekel, R., Van Dishoeck, E. F., Vermot, P., Vincent, F., Von fellenberg, S., Waisberg, I., Wang, J. J., Wank, I., Weber, J., Weigelt, G., Widmann, F., Wieprecht, E., Wiest, M., Wiezorrek, E., Wittkowski, M., Woillez, J., Wolff, B., Yang, P., Yazici, S., Ziegler, D., Zins, G., and European Southern Observatory (ESO)

Subjects
[SDU]Sciences of the Universe [physics], Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

More than 4000 exoplanets are known to date in systems that differ greatly from our Solar System. In particular, inner exoplanets tend to follow orbits around their parent star that are much more compact than that of Earth. These systems are also extremely diverse, covering a range of intrinsic properties. Studying the main physi- cal processes at play in the innermost regions of the protoplanetary discs is crucial to understanding how these planets form and migrate so close to their host. With GRAVITY, we focused on the study of near-infrared emission of a sample of young intermediate- mass stars, the Herbig Ae/Be stars., Published in The Messenger vol. 178, pp. 38-40, December 2019.

Published
2019
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103. Protected Area management: Fusion and confusion with the ecosystem services approach

Author

Hummel, C., Poursanidis, D., Orenstein, D., Elliott, M., Adamescu, M.C., Cazacu, C., Ziv, G., Chrysoulakis, N., Van der Meer, J., Hummel, H., Hummel, C., Poursanidis, D., Orenstein, D., Elliott, M., Adamescu, M.C., Cazacu, C., Ziv, G., Chrysoulakis, N., Van der Meer, J., and Hummel, H.

Abstract

For many years, Protected Areas (PA) have been an important tool for conserving nature. Recently, also societal aspects have been introduced into PA management via the introduction of the Ecosystem Services (ES) approach. This review discusses the historical background of PAs, PA management, and the ES approach. We then discuss the relevance and applicability of the ES approach for PA management, including the different definitions of ES, different classification methods, and the ways in which ES are measured. We conclude that there are still major challenges ahead in using the ES approach in PA management and so recommendations are given on the way in which the ES approach should be integrated into PA management.

Published
2019

104. 2006 interferometry imaging beauty contest

Author

Chesneau, O, Weigelt, G. P, Hoffman, K. - H, Kraus, S, Rengaswamy, Sridharan, Thiebaut, E. M, Young, J. S, Baron, F, Monnier, J. D, Ireland, M, Hummel, C. A, Cotton, W. D, and Lawson, Peter R

Abstract

UNKNOWN

Published
2006

105. 2006 interferometry imaging beauty contest

Author

Lawson, Peter R, Cotton, W. D, Hummel, C. A, Ireland, M, Monnier, J. D, Baron, F, Young, J. S, Thiebaut, E. M, Rengaswamy, Sridharan, Kraus, S, Hoffman, K. - H, Weigelt, G. P, and Chesneau, O

Published
2006

109. An interferometry imaging beauty contest

Author

Lawson, Peter R, Cotton, W. D, Hummel, C. A, Monnier, J. D, Zhao, M, Young, J. S, Thorsteinsson, H, Meimon, S. C, Mugnier, L, Le Besnerais, G, Thiebaut, E, and Tuthill, P. G

Published
2004

110. An interferometry imaging beauty contest

Author

Tuthill, P. G, Thiebaut, E, Le Besnerais, G, Mugnier, L, Meimon, S. C, Thorsteinsson, H, Young, J. S, Zhao, M, Monnier, J. D, Hummel, C. A, Cotton, W. D, and Lawson, Peter R

Abstract

UNKNOWN

Published
2004

116. Analysis of coastal areas using SAR images: A case study of the Dutch Wadden Sea region

Author

Dumitru, C.O., Schwartz, G., Espinoza-Molina, D., Datcu, M., Hummel, H., and Hummel, C.

Abstract

The increased availability of civil synthetic aperture radar (SAR) satellite images withdifferent resolution allows us to compare the imaging capabilities of these instruments, toassess the quality of the available data and to investigate different areas (e.g., the Wadden Sea region). In our investigation, we propose to explore the content of Terra SAR-X and Sentinel-1A satellite images via a data mining approach in which the main steps are patch tiling, feature extraction, classification, semantic annotation and visual-statistical analytics. Once all the extracted categories are mapped and quantified, then the next step is to interpret them from an environmental point of view. The objective of our study is the application of semi-automated SAR image interpretation. Its novelty is the automated multiclass categorisation of coastal areas. We found out that the north-west of the Netherlands can be interpreted routinely as land surfaces by our satellite image analyses,while for the Wadden Sea, we can discriminate the different water levels and their impact on the visibility of the tidal flats. This necessitates a selection of time series data spanning a full tidal cycle.

Published
2018

117. GRAVITY chromatic imaging of η Car's core. Milliarcsecond resolution imaging of the wind-wind collision zone (Brγ, He I)

Author

Collaboration, G., Sanchez-Bermudez, J., Weigelt, G., Bestenlehner, J., Kervella, P., Brandner, W., Henning, T., Müller, A., Perrin, G., Pott, J., Schöller, M., van Boekel, R., Abuter, R., Accardo, M., Amorim, A., Anugu, N., Ávila, G., Benisty, M., Berger, J., Blind, N., Bonnet, H., Bourget, P., Brast, R., Buron, A., Cantalloube, F., Caratti O Garatti, A., Cassaing, F., Chapron, F., Choquet, E., Clénet, Y., Collin, C., Coudé Du Foresto, V., de Wit, W., de Zeeuw, T., Deen, C., Delplancke-Ströbele, F., Dembet, R., Derie, F., Dexter, J., Duvert, G., Ebert, M., Eckart, A., Eisenhauer, F., Esselborn, M., Fédou, P., Garcia, P., Garcia Dabo, C., Garcia Lopez, R., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Haubois, X., Haug, M., Haussmann, F., Hippler, S., Horrobin, M., Huber, A., Hubert, Z., Hubin, N., Hummel, C., Jakob, G., Jochum, L., Jocou, L., Karl, M., Kaufer, A., Kellner, S., Kendrew, S., Kern, L., Kiekebusch, M., Klein, R., Kolb, J., Kulas, M., Lacour, S., Lapeyrère, V., Lazareff, B., Le Bouquin, J., Léna, P., Lenzen, R., Lévêque, S., Lippa, M., Magnard, Y., Mehrgan, L., Mellein, M., Mérand, A., Moreno-Ventas, J., Moulin, T., Müller, E., Müller, F., Neumann, U., Oberti, S., Ott, T., Pallanca, L., Panduro, J., Pasquini, L., Paumard, T., Percheron, I., Perraut, K., Petrucci, P., Pflüger, A., Pfuhl, O., Duc, T., Plewa, P., Popovic, D., Rabien, S., Ramirez, A., Ramos, J., Rau, C., Riquelme, M., Rodríguez-Coira, G., Rohloff, R., Rosales, A., Rousset, G., Scheithauer, S., Schuhler, N., Spyromilio, J., Straub, O., Straubmeier, C., Sturm, E., Suarez, M., Tristram, K., Ventura, N., Vincent, F., Waisberg, I., Wank, I., Widmann, F., Wieprecht, E., Wiest, M., Wiezorrek, E., Wittkowski, M., Woillez, J., Wolff, B., Yazici, S., Ziegler, D., and Zins, G.

Subjects
Astrophysics::Solar and Stellar Astrophysics
Abstract

Context. η Car is one of the most intriguing luminous blue variables in the Galaxy. Observations and models of the X-ray, ultraviolet, optical, and infrared emission suggest a central binary in a highly eccentric orbit with a 5.54 yr period residing in its core. 2D and 3D radiative transfer and hydrodynamic simulations predict a primary with a dense and slow stellar wind that interacts with the faster and lower density wind of the secondary. The wind-wind collision scenario suggests that the secondary's wind penetrates the primary's wind creating a low-density cavity in it, with dense walls where the two winds interact. However, the morphology of the cavity and its physical properties are not yet fully constrained. Aims: We aim to trace the inner ̃5-50 au structure of η Car's wind-wind interaction, as seen through Brγ and, for the first time, through the He I 2s-2p line. Methods: We have used spectro-interferometric observations with the K-band beam-combiner GRAVITY at the VLTI. The analyses of the data include (i) parametrical model-fitting to the interferometric observables, (ii) a CMFGEN model of the source's spectrum, and (iii) interferometric image reconstruction. Results: Our geometrical modeling of the continuum data allows us to estimate its FWHM angular size close to 2 mas and an elongation ratio ∊ = 1.06 ± 0.05 over a PA = 130° ± 20°. Our CMFGEN modeling of the spectrum helped us to confirm that the role of the secondary should be taken into account to properly reproduce the observed Brγ and He I lines. Chromatic images across the Brγ line reveal a southeast arc-like feature, possibly associated to the hot post-shocked winds flowing along the cavity wall. The images of the He I 2s-2p line served to constrain the 20 mas (̃50 au) structure of the line-emitting region. The observed morphology of He I suggests that the secondary is responsible for the ionized material that produces the line profile. Both the Brγ and the He I 2s-2p maps are consistent with previous hydrodynamical models of the colliding wind scenario. Future dedicated simulations together with an extensive interferometric campaign are necessary to refine our constraints on the wind and stellar parameters of the binary, which finally will help us predict the evolutionary path of η Car.

Published
2018

130. GRAVITY chromatic imaging of eta Car's core Milliarcsecond resolution imaging of the wind-wind collision zone (Br gamma, He i)

Author

Sanchez-Bermudez, J., Weigelt, G., Bestenlehner, J. M., Kervella, P., Brandner, W., Henning, Th, Mueller, A., Perrin, G., Pott, J-U, Schoeller, M., van Boeke, R., Abuter, R., Accardo, M., Amorim, A., Anugu, N., Avila, G., Benisty, M., Berger, J. P., Blind, N., Bonnet, H., Bourget, P., Brast, R., Buron, A., Cantalloube, F., Garatti, A. Caratti O., Cassaing, F., Chapron, F., Choquet, E., Clenet, Y., Collin, C., du Foresto, V. Coude, de Wit, W., de Zeeuw, T., Deen, C., Delplancke-Stroebele, F., Dembet, R., Derie, F., Dexter, J., Duvert, G., Ebert, M., Eckart, A., Eisenhauer, F., Esselborn, M., Fedou, P., Garcia, P. J., V, Dabo, C. E. Garcia, Lopez, R. Garcia, Gao, F., Gendron, E., Genzel, R., Gillessen, S., Haubois, X., Haug, M., Haussmann, F., Hippler, S., Horrobin, M., Huber, A., Hubert, Z., Hubin, N., Hummel, C. A., Jakob, G., Jochum, L., Jocou, L., Karl, M., Kaufer, A., Kellner, S., Kendrew, S., Kern, L., Kiekebusch, M., Klein, R., Kolb, J., Kulas, M., Lacour, S., Lapeyrere, V, Lazareff, B., Le Bouquin, J-B, Lena, P., Lenzen, R., Leveque, S., Lippa, M., Magnard, Y., Mehrgan, L., Mellein, M., Merand, A., Moreno-Ventas, J., Moulin, T., Mueller, E., Mueller, F., Neumann, U., Oberti, S., Ott, T., Pallanca, L., Panduro, J., Pasquini, L., Paumard, T., Percheron, I, Perraut, K., Petrucci, P-O, Pflueger, A., Pfuhl, O., Duc, T. P., Plewa, P. M., Popovic, D., Rabien, S., Ramirez, A., Ramos, J., Rau, C., Riquelme, M., Rodriguez-Coira, G., Rohloff, R-R, Rosales, A., Rousset, G., Scheithauer, S., Schuhler, N., Spyromilio, J., Straub, O., Straubmeier, C., Sturm, E., Suarez, M., Tristram, K. R. W., Ventura, N., Vincent, F., Waisberg, I, Wank, I, Widmann, F., Wieprecht, E., Wiest, M., Wiezorrek, E., Wittkowski, M., Woillez, J., Wolff, B., Yazici, S., Ziegler, D., Zins, G., Sanchez-Bermudez, J., Weigelt, G., Bestenlehner, J. M., Kervella, P., Brandner, W., Henning, Th, Mueller, A., Perrin, G., Pott, J-U, Schoeller, M., van Boeke, R., Abuter, R., Accardo, M., Amorim, A., Anugu, N., Avila, G., Benisty, M., Berger, J. P., Blind, N., Bonnet, H., Bourget, P., Brast, R., Buron, A., Cantalloube, F., Garatti, A. Caratti O., Cassaing, F., Chapron, F., Choquet, E., Clenet, Y., Collin, C., du Foresto, V. Coude, de Wit, W., de Zeeuw, T., Deen, C., Delplancke-Stroebele, F., Dembet, R., Derie, F., Dexter, J., Duvert, G., Ebert, M., Eckart, A., Eisenhauer, F., Esselborn, M., Fedou, P., Garcia, P. J., V, Dabo, C. E. Garcia, Lopez, R. Garcia, Gao, F., Gendron, E., Genzel, R., Gillessen, S., Haubois, X., Haug, M., Haussmann, F., Hippler, S., Horrobin, M., Huber, A., Hubert, Z., Hubin, N., Hummel, C. A., Jakob, G., Jochum, L., Jocou, L., Karl, M., Kaufer, A., Kellner, S., Kendrew, S., Kern, L., Kiekebusch, M., Klein, R., Kolb, J., Kulas, M., Lacour, S., Lapeyrere, V, Lazareff, B., Le Bouquin, J-B, Lena, P., Lenzen, R., Leveque, S., Lippa, M., Magnard, Y., Mehrgan, L., Mellein, M., Merand, A., Moreno-Ventas, J., Moulin, T., Mueller, E., Mueller, F., Neumann, U., Oberti, S., Ott, T., Pallanca, L., Panduro, J., Pasquini, L., Paumard, T., Percheron, I, Perraut, K., Petrucci, P-O, Pflueger, A., Pfuhl, O., Duc, T. P., Plewa, P. M., Popovic, D., Rabien, S., Ramirez, A., Ramos, J., Rau, C., Riquelme, M., Rodriguez-Coira, G., Rohloff, R-R, Rosales, A., Rousset, G., Scheithauer, S., Schuhler, N., Spyromilio, J., Straub, O., Straubmeier, C., Sturm, E., Suarez, M., Tristram, K. R. W., Ventura, N., Vincent, F., Waisberg, I, Wank, I, Widmann, F., Wieprecht, E., Wiest, M., Wiezorrek, E., Wittkowski, M., Woillez, J., Wolff, B., Yazici, S., Ziegler, D., and Zins, G.

Abstract

Context. eta Car is one of the most intriguing luminous blue variables in the Galaxy. Observations and models of the X-ray, ultraviolet, optical, and infrared emission suggest a central binary in a highly eccentric orbit with a 5.54 yr period residing in its core. 2D and 3D radiative transfer and hydrodynamic simulations predict a primary with a dense and slow stellar wind that interacts with the faster and lower density wind of the secondary. The wind-wind collision scenario suggests that the secondary's wind penetrates the primary's wind creating a low-density cavity in it, with dense walls where the two winds interact. However, the morphology of the cavity and its physical properties are not yet fully constrained. Aims. We aim to trace the inner similar to 5-50 au structure of eta Car's wind-wind interaction, as seen through Br gamma and, for the first time, through the He i 2s-2p line. Methods. We have used spectro-interferometric observations with the K-band beam-combiner GRAVITY at the VLTI. The analyses of the data include (i) parametrical model-fitting to the interferometric observables, (ii) a CMFGEN model of the source's spectrum, and (iii) interferometric image reconstruction. Results. Our geometrical modeling of the continuum data allows us to estimate its FWHM angular size close to 2 mas and an elongation ratio epsilon = 1.06 +/- 0.05 over a PA = 130 degrees +/- 20 degrees. Our CMFGEN modeling of the spectrum helped us to confirm that the role of the secondary should be taken into account to properly reproduce the observed Br gamma and He i lines. Chromatic images across the Br gamma line reveal a southeast arc-like feature, possibly associated to the hot post-shocked winds flowing along the cavity wall. The images of the He i 2s-2p line served to constrain the 20 mas (similar to 50 au) structure of the line-emitting region. The observed morphology of He i suggests that the secondary is responsible for the ionized material that produces the line profile

Published
2018

131. Weak Magnetic Fields in Two Herbig Ae Systems:The SB2 AK Sco and the Presumed Binary HD 95881

Author

Jaervinen, S. P., Carroll, T. A., Hubrig, S., Ilyin, I., Schoeller, M., Castelli, F., Hummel, C. A., Petr-Gotzens, M. G., Korhonen, H., Weigelt, G., Pogodin, M. A., Drake, N. A., Jaervinen, S. P., Carroll, T. A., Hubrig, S., Ilyin, I., Schoeller, M., Castelli, F., Hummel, C. A., Petr-Gotzens, M. G., Korhonen, H., Weigelt, G., Pogodin, M. A., and Drake, N. A.

Published
2018

132. Stability of FORS2 Sky Flats

Author

Boffin, Henri M. J., Dobrzycka, D., Hummel, C., Moehler, S., Smoker, J., Anderson, J., and Dias, B.

Abstract

"The FORS2 calibration plan previously had a validity for imaging sky flatfields of four days. This placed some stress on the observers, especially during periods of bad weather. We therefore decided to analyse a series of flats to check if it was possible to extend this validity range, and if yes, to what level. The analysis allowed us to change the FORS2 calibration plan, increasing the validity of sky flats from four to 14 days."

Published
2017
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133. The orbit of Phi Cygni measured with long-baseline optical interferometry - Component masses and absolute magnitudes

Author

Armstrong, J. T, Hummel, C. A, Quirrenbach, A, Buscher, D. F, Mozurkewich, D, Vivekanand, M, Simon, R. S, Denison, C. S, Johnston, K. J, and Pan, X.-P

Subjects
Astronomy
Abstract

The orbit of the double-lined spectroscopic binary Phi Cygni, the distance to the system, and the masses and absolute magnitudes of its components are presented via measurements with the Mar III Optical Interferometer. On the basis of a reexamination of the spectroscopic data of Rach & Herbig (1961), the values and uncertainties are adopted for the period and the projected semimajor axes from the present fit to the spectroscopic data and the values of the remaining elements from the present fit to the Mark III data. The elements of the true orbit are derived, and the masses and absolute magnitudes of the components, and the distance to the system are calculated.

Published
1992
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134. The very slow rotation of the magnetic O9.7 V star HD 54879.

Author

Hubrig, S, Järvinen, S P, Schöller, M, and Hummel, C A

Subjects
STELLAR magnetic fields, MAGNETIC flux density, ABSOLUTE value, STELLAR rotation, ROTATIONAL motion, MAGNETIC fields, SIGNAL-to-noise ratio
Abstract

The first FOcal Reducer low dispersion Spectrograph (FORS 2) spectropolarimetric observation of the longitudinal magnetic field of HD 54879 of the order of −600 G with a lower limit of the dipole strength of ∼2 kG dates back to 2014. Since then, observations showed a gradual decrease of the absolute value of the mean longitudinal magnetic field. In the course of the most recent monitoring of HD 54879 using FORS 2 spectropolarimetric observations from 2017 October to 2018 February, a longitudinal magnetic field strength change from about −300 G down to about −90 G was reported. A sudden increase of the absolute value of the mean longitudinal magnetic field and an accompanying spectral variability was detected on 2018 February 17. New FORS 2 spectropolarimetric data obtained from 2018 December to 2019 February confirm the very slow magnetic field variability, with the field decreasing from about 150 G to −100 G over 2 months. Such a slow magnetic field variability, related to the extremely slow rotation of HD 54879, is also confirmed using high-resolution High Accuracy Radial velocity Planet Searcher in polarimetric mode and Echelle SpectroPolarimetric Device for the Observation of Stars spectropolarimetry. The re-analysis of the FORS 2 polarimetric spectra from 2018 February indicates that the previously reported field increase and the change of the spectral appearance was caused by improper spectra extraction and wavelength calibration using observations obtained at an insufficient signal-to-noise ratio. The presented properties of HD 54879 are discussed in the context of the Of?p spectral classification. [ABSTRACT FROM AUTHOR]

Published
2020
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138. First light for GRAVITY: Phase referencing optical interferometry for the Very Large Telescope Interferometer

Author

Abuter, R., Accardo, M., Amorim, A., Anugu, N., Avila, G., Azouaoui, N., Benisty, M., Berger, J. P., Blind, N., Bonnet, H., Bourget, P., Brandner, W., Brast, R., Buron, A., Burtscher, L., Cassaing, F., Chapron, F., Choquet, E., Clenet, Y., Collin, C., du Foresto, V. Coude, de Wit, W., de Zeeuw, P. T., Deen, C., Delplancke-Stroebele, F., Dembet, R., Derie, F., Dexter, J., Duvert, G., Ebert, M., Eckart, A., Eisenhauer, F., Esselborn, M., Fedou, P., Finger, G., Garcia, P., Dabo, C. E. Garcia, Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Gonte, F., Gordo, P., Grould, M., Groezinger, U., Guieu, S., Haguenauer, P., Hans, O., Haubois, X., Haug, M., Haussmann, F., Henning, Th., Hippler, S., Horrobin, M., Huber, A., Hubert, Z., Hubin, N., Hummel, C. A., Jakob, G., Janssen, A., Jochum, L., Jocou, L., Kaufer, A., Kellner, S., Kendrew, S., Kern, L., Kervella, P., Kiekebusch, M., Klein, R., Kok, Y., Kolb, J., Kulas, M., Lacour, S., Lapeyrere, V., Lazareff, B., Le Bouquin, J. -B., Lena, P., Lenzen, R., Leveque, S., Lippa, M., Magnard, Y., Mehrgan, L., Mellein, M., Merand, A., Moreno-Ventas, J., Moulin, T., Mueller, E., Mueller, F., Neumann, U., Oberti, S., Ott, T., Pallanca, L., Panduro, J., Pasquini, L., Paumard, T., Percheron, I., Perraut, K., Perrin, G., Pflueger, A., Pfuhl, O., Duc, T. Phan, Plewa, P. M., Popovic, D., Rabien, S., Ramirez, A., Ramos, J., Rau, C., Riquelme, M., Rohloff, R. -R., Rousset, G., Sanchez-Bermudez, J., Scheithauer, S., Schoeller, M., Schuhler, N., Spyromilio, J., Straubmeier, C., Sturm, E., Suarez, M., Tristram, K. R. W., Ventura, N., Vincent, F., Waisberg, I., Wank, I., Weber, J., Wieprecht, E., Wiest, M., Wiezorrek, E., Wittkowski, M., Woillez, J., Wolff, B., Yazici, S., Ziegler, D., Zins, G., Abuter, R., Accardo, M., Amorim, A., Anugu, N., Avila, G., Azouaoui, N., Benisty, M., Berger, J. P., Blind, N., Bonnet, H., Bourget, P., Brandner, W., Brast, R., Buron, A., Burtscher, L., Cassaing, F., Chapron, F., Choquet, E., Clenet, Y., Collin, C., du Foresto, V. Coude, de Wit, W., de Zeeuw, P. T., Deen, C., Delplancke-Stroebele, F., Dembet, R., Derie, F., Dexter, J., Duvert, G., Ebert, M., Eckart, A., Eisenhauer, F., Esselborn, M., Fedou, P., Finger, G., Garcia, P., Dabo, C. E. Garcia, Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Gonte, F., Gordo, P., Grould, M., Groezinger, U., Guieu, S., Haguenauer, P., Hans, O., Haubois, X., Haug, M., Haussmann, F., Henning, Th., Hippler, S., Horrobin, M., Huber, A., Hubert, Z., Hubin, N., Hummel, C. A., Jakob, G., Janssen, A., Jochum, L., Jocou, L., Kaufer, A., Kellner, S., Kendrew, S., Kern, L., Kervella, P., Kiekebusch, M., Klein, R., Kok, Y., Kolb, J., Kulas, M., Lacour, S., Lapeyrere, V., Lazareff, B., Le Bouquin, J. -B., Lena, P., Lenzen, R., Leveque, S., Lippa, M., Magnard, Y., Mehrgan, L., Mellein, M., Merand, A., Moreno-Ventas, J., Moulin, T., Mueller, E., Mueller, F., Neumann, U., Oberti, S., Ott, T., Pallanca, L., Panduro, J., Pasquini, L., Paumard, T., Percheron, I., Perraut, K., Perrin, G., Pflueger, A., Pfuhl, O., Duc, T. Phan, Plewa, P. M., Popovic, D., Rabien, S., Ramirez, A., Ramos, J., Rau, C., Riquelme, M., Rohloff, R. -R., Rousset, G., Sanchez-Bermudez, J., Scheithauer, S., Schoeller, M., Schuhler, N., Spyromilio, J., Straubmeier, C., Sturm, E., Suarez, M., Tristram, K. R. W., Ventura, N., Vincent, F., Waisberg, I., Wank, I., Weber, J., Wieprecht, E., Wiest, M., Wiezorrek, E., Wittkowski, M., Woillez, J., Wolff, B., Yazici, S., Ziegler, D., and Zins, G.

Abstract

GRAVITY is a new instrument to coherently combine the light of the European Southern Observatory Very Large Telescope Interferometer to form a telescope with an equivalent 130m diameter angular resolution and a collecting area of 200 m(2). The instrument comprises fiber fed integrated optics beam combination, high resolution spectroscopy, built-in beam analysis and control, near-infrared wavefront sensing, phase-tracking, dual-beam operation, and laser metrology. GRAVITY opens up to optical/infrared interferometry the techniques of phase referenced imaging and narrow angle astrometry, in many aspects following the concepts of radio interferometry. This article gives an overview of GRAVITY and reports on the performance and the first astronomical observations during commissioning in 2015/16. We demonstrate phase-tracking on stars as faint as m(K) approximate to 10 mag, phase-referenced interferometry of objects fainter than m(K) approximate to 15 mag with a limiting magnitude of m(K) approximate to 17 mag, minute long coherent integrations, a visibility accuracy of better than 0.25%, and spectro-differential phase and closure phase accuracy better than 0.5 degrees, corresponding to a differential astrometric precision of better than ten microarcseconds (as). The dual-beam astrometry, measuring the phase difference of two objects with laser metrology, is still under commissioning. First observations show residuals as low as 50 mu as when following objects over several months. We illustrate the instrument performance with the observations of archetypical objects for the different instrument modes. Examples include the Galactic center supermassive black hole and its fast orbiting star S2 for phase referenced dual-beam observations and infrared wavefront sensing, the high mass X-ray binary BP Cru and the active galactic nucleus of PDS 456 for a few mu as spectro-differential astrometry, the T Tauri star S CrA for a spectro-differential visibility analysis, xi Tel and 24

Published
2017

139. Orbital Elements and Stellar Parameters of the Active Binary UX Arietis

Author

Hummel, C. A., Monnier, J. D., Roettenbacher, Rachael M., Torres, G., Henry, G. W., Korhonen, H., Beasley, A., Schaefer, G. H., Turner, N. H., Ten Brummelaar, T., Farrington, C. D., Sturmann, J., Sturmann, L., Baron, F., Kraus, S., Hummel, C. A., Monnier, J. D., Roettenbacher, Rachael M., Torres, G., Henry, G. W., Korhonen, H., Beasley, A., Schaefer, G. H., Turner, N. H., Ten Brummelaar, T., Farrington, C. D., Sturmann, J., Sturmann, L., Baron, F., and Kraus, S.

Abstract

Stellar activity observed as large surface spots, radio flares, or emission lines is often found in binary systems. UX Arietis exhibits these signs of activity, originating on the K0 subgiant primary component. Our aim is to resolve the binary, measure the orbital motion, and provide accurate stellar parameters such as masses and luminosities to aid in the interpretation of the observed phenomena. Using the CHARA six-telescope optical long-baseline array on Mount Wilson, California, we obtained amplitudes and phases of the interferometric visibility on baselines up to 330 m in length, resolving the two components of the binary. We reanalyzed archival Center for Astrophysics spectra to disentangle the binary component spectra and the spectrum of the third component, which was resolved by speckle interferometry. We also obtained new spectra with the Nordic Optical Telescope, and we present new photometric data that we use to model stellar surface spot locations. Both interferometric visibilities and spectroscopic radial velocities are modeled with a spotted primary stellar surface using the Wilson-Devinney code. We fit the orbital elements to the apparent orbit and radial velocity data to derive the distance (52.1 +/- 0.8 pc) and stellar masses (M-P = 1.30 +/- 0.06 M-circle dot, M-S = 1.14 +/- 0.06 M-circle dot). The radius of the primary can be determined to be R-P = 5.6 +/- 0.1 R-circle dot and that of the secondary to be R-S = 1.6 +/- 0.2 R-circle dot. The equivalent spot coverage of the primary component was found to be 62% with an effective temperature 20% below that of the unspotted surface.

Published
2017
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141. Ecosystem services in European protected areas: Ambiguity in the views of scientists and managers?

Author

Hummel, C., Provenzale, A., Van der Meer, J., Wijnhoven, S., Nolte, A., Poursanidis, D., Janss, G., Jurek, M., Andresen, M., Poulin, B., Kobler, J., Beierkuhnlein, C., Honrado, J., Razinkovas, A., Stritih, A., Bargmann, T., Ziemba, A., Bonet-García, F., Adamescu, M.C., Janssen, G., Hummel, H., Hummel, C., Provenzale, A., Van der Meer, J., Wijnhoven, S., Nolte, A., Poursanidis, D., Janss, G., Jurek, M., Andresen, M., Poulin, B., Kobler, J., Beierkuhnlein, C., Honrado, J., Razinkovas, A., Stritih, A., Bargmann, T., Ziemba, A., Bonet-García, F., Adamescu, M.C., Janssen, G., and Hummel, H.

Abstract

Protected Areas are a key component of nature conservation. They can play an important role in counterbalancing the impacts of ecosystem degradation. For an optimal protection of a Protected Area it is essential to account for the variables underlying the major Ecosystem Services an area delivers, and the threats upon them. Here we show that the perception of these important variables differs markedly between scientists and managers of Protected Areas in mountains and transitional waters. Scientists emphasise variables of abiotic and biotic nature, whereas managers highlight socio-economic, cultural and anthropogenic variables. This indicates fundamental differences in perception. To be able to better protect an area it would be advisable to bring the perception of scientists and managers closer together. Intensified and harmonised communication across disciplinary and professional boundaries will be needed to implement and improve Ecosystem Service oriented management strategies in current and future Protected Areas

Published
2017

145. Orbital Elements and Stellar Parameters of the Active Binary UX Arietis

Author

Hummel, C. A., primary, Monnier, J. D., additional, Roettenbacher, R. M., additional, Torres, G., additional, Henry, G. W., additional, Korhonen, H., additional, Beasley, A., additional, Schaefer, G. H., additional, Turner, N. H., additional, Brummelaar, T. Ten, additional, Farrington, C. D., additional, Sturmann, J., additional, Sturmann, L., additional, Baron, F., additional, and Kraus, S., additional

Published
2017
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148. ORBITS, DISTANCE, AND STELLAR MASSES OF THE MASSIVE TRIPLE STARσORIONIS

Author

Schaefer, G. H., primary, Hummel, C. A., additional, Gies, D. R., additional, Zavala, R. T., additional, Monnier, J. D., additional, Walter, F. M., additional, Turner, N. H., additional, Baron, F., additional, Brummelaar, T. ten, additional, Che, X., additional, Farrington, C. D., additional, Kraus, S., additional, Sturmann, J., additional, and Sturmann, L., additional

Published
2016
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150. Making FORS2 fit for exoplanet observations (again)

Author

Boffin, H., Blanchard, G., Gonzalez, O., Moehler, S., Sedaghati, E., Gibson, N., Mario van den Ancker, Smoker, J., Anderson, J., Hummel, C., Dobrzycka, D., Smette, A., and Rupprecht, G.

Subjects
Physics - Instrumentation and Detectors, Astrophysics - Solar and Stellar Astrophysics, FOS: Physical sciences, Instrumentation and Detectors (physics.ins-det), Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

For about three years, it was known that precision spectrophotometry with FORS2 suffered from systematic errors that made quantitative observations of planetary transits impossible. We identified the Longitudinal Atmospheric Dispersion Compensator (LADC) as the most likely culprit, and therefore engaged in a project to exchange the LADC prisms with the uncoated ones from FORS1. This led to a significant improvement in the depth of FORS2 zero points, a reduction in the systematic noise, and should make FORS2 again competitive for transmission spectroscopy of exoplanets., Comment: To appear in the March issue of the ESO Messenger

Published
2015
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