@article{AhnenAnsoldiAntonellietal.2017,
  author    = {Ahnen, M. L. and Ansoldi, S. and Antonelli, L. A. and Antoranz, P. and Babic, A. and Banerjee, B. and Bangale, P. and de Almeida, U. Barres and Barrio, J. A. and Gonzalez, J. Becerra and Bednarek, W. and Bernardini, E. and Berti, A. and Biasuzzi, B. and Biland, A. and Blanch, O. and Bonnefoy, S. and Bonnoli, G. and Borracci, F. and Bretz, T. and Buson, S. and Carosi, A. and Chatterjee, A. and Clavero, R. and Colin, P. and Colombo, E. and Contreras, J. L. and Cortina, J. and Covino, S. and Da Vela, P. and Dazzi, F. and De Angelis, A. and De Lotto, B. and Wilhelmi, E. de Ona and Di Pierro, F. and Doert, M. and Dominguez, A. and Prester, D. Dominis and Dorner, D. and Doro, M. and Einecke, S. and Glawion, D. Eisenacher and Elsaesser, D. and Engelkemeier, M. and Ramazani, V. Fallah and Fernandez-Barral, A. and Fidalgo, D. and Fonseca, M. V. and Font, L. and Frantzen, K. and Fruck, C. and Galindo, D. and Lopez, R. J. Garcia and Garczarczyk, M. and Terrats, D. Garrido and Gaug, M. and Giammaria, P. and Godinovic, N. and Gonzalez Munoz, A. and Gora, D. and Guberman, D. and Hadasch, D. and Hahn, A. and Hanabata, Y. and Hayashida, M. and Herrera, J. and Hose, J. and Hrupec, D. and Hughes, G. and Idec, W. and Kodani, K. and Konno, Y. and Kubo, H. and Kushida, J. and La Barbera, A. and Lelas, D. and Lindfors, E. and Lombardi, S. and Longo, F. and Lopez, M. and Lopez-Coto, R. and Majumdar, P. and Makariev, M. and Mallot, K. and Maneva, G. and Manganaro, M. and Mannheim, K. and Maraschi, L. and Marcote, B. and Mariotti, M. and Martinez, M. and Mazin, D. and Menzel, U. and Miranda, J. M. and Mirzoyan, R. and Moralejo, A. and Moretti, E. and Nakajima, D. and Neustroev, V. and Niedzwiecki, A. and Rosillo, M. Nievas and Nilsson, K. and Nishijima, K. and Noda, K. and Nogues, L. and Overkemping, A. and Paiano, S. and Palacio, J. and Palatiello, M. and Paneque, D. and Paoletti, R. and Paredes, J. M. and Paredes-Fortuny, X. and Pedaletti, G. and Peresano, M. and Perri, L. and Persic, M. and Poutanen, J. and Moroni, P. G. Prada and Prandini, E. and Puljak, I. and Reichardt, I. and Rhode, W. and Ribo, M. and Rico, J. and Rodriguez Garcia, J. and Saito, T. and Satalecka, K. and Schroder, S. and Schultz, C. and Schweizer, T. and Shore, S. N. and Sillanpaa, A. and Sitarek, J. and Snidaric, I. and Sobczynska, D. and Stamerra, A. and Steinbring, T. and Strzys, M. and Suric, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Terzic, T. and Tescaro, D. and Teshima, M. and Thaele, J. and Torres, D. F. and Toyama, T. and Treves, A. and Vanzo, G. and Verguilov, V. and Vovk, I. and Ward, J. E. and Will, M. and Wu, M. H. and Zanin, R. and Abeysekara, A. U. and Archambault, S. and Archer, A. and Benbow, W. and Bird, R. and Buchovecky, M. and Buckley, J. H. and Bugaev, V. and Connolly, M. P. and Cui, W. and Dickinson, H. J. and Falcone, A. and Feng, Q. and Finley, J. P. and Fleischhack, H. and Flinders, A. and Fortson, L. and Gillanders, G. H. and Griffin, S. and Grube, J. and Huetten, M. and Hanna, D. and Holder, J. and Humensky, T. B. and Kaaret, P. and Kar, P. and Kelley-Hoskins, N. and Kertzman, M. and Kieda, D. and Krause, M. and Krennrich, F. and Lang, M. J. and Maier, G. and McCann, A. and Moriarty, P. and Mukherjee, R. and Nieto, D. and Ong, R. A. and Otte, N. and Park, N. and Perkins, J. and Pichel, A. and Pohl, M. and Popkow, A. and Pueschel, Elisa and Quinn, J. and Ragan, K. and Reynolds, P. T. and Richards, G. T. and Roache, E. and Rovero, A. C. and Rulten, C. and Sadeh, I. and Santander, M. and Sembroski, G. H. and Shahinyan, K. and Telezhinsky, Igor O. and Tucci, J. V. and Tyler, J. and Wakely, S. P. and Weinstein, A. and Wilcox, P. and Wilhelm, Alina and Williams, D. A. and Zitzer, B. and Razzaque, S. and Villata, M. and Raiteri, C. M. and Aller, H. D. and Aller, M. F. and Larionov, V. M. and Arkharov, A. A. and Blinov, D. A. and Efimova, N. V. and Grishina, T. S. and Hagen-Thorn, V. A. and Kopatskaya, E. N. and Larionova, L. V. and Larionova, E. G. and Morozova, D. A. and Troitsky, I. S. and Ligustri, R. and Calcidese, P. and Berdyugin, A. and Kurtanidze, O. M. and Nikolashvili, M. G. and Kimeridze, G. N. and Sigua, L. A. and Kurtanidze, S. O. and Chigladze, R. A. and Chen, W. P. and Koptelova, E. and Sakamoto, T. and Sadun, A. C. and Moody, J. W. and Pace, C. and Pearson, R. and Yatsu, Y. and Mori, Y. and Carraminyana, A. and Carrasco, L. and de la Fuente, E. and Norris, J. P. and Smith, P. S. and Wehrle, A. and Gurwell, M. A. and Zook, A. and Pagani, C. and Perri, M. and Capalbi, M. and Cesarini, A. and Krimm, H. A. and Kovalev, Y. Y. and Kovalev, Yu. A. and Ros, E. and Pushkarev, A. B. and Lister, M. L. and Sokolovsky, K. V. and Kadler, M. and Piner, G. and Lahteenmaki, A. and Tornikoski, M. and Angelakis, E. and Krichbaum, T. P. and Nestoras, I. and Fuhrmann, L. and Zensus, J. A. and Cassaro, P. and Orlati, A. and Maccaferri, G. and Leto, P. and Giroletti, M. and Richards, J. L. and Max-Moerbeck, W. and Readhead, A. C. S.},
  title     = {Multiband variability studies and novel broadband SED modeling of Mrk 501 in 2009},
  series = {Astronomy and astrophysics : an international weekly journal},
  volume    = {603},
  journal   = {Astronomy and astrophysics : an international weekly journal},
  publisher = {EDP Sciences},
  address   = {Les Ulis},
  organization    = {MAGIC Collaboration;VERITAS Collaboration},
  issn      = {1432-0746},
  doi       = {10.1051/0004-6361/201629540},
  pages     = {30},
  year      = {2017},
  abstract  = {Aims. We present an extensive study of the BL Lac object Mrk 501 based on a data set collected during the multi-instrument campaign spanning from 2009 March 15 to 2009 August 1, which includes, among other instruments, MAGIC, VERITAS, Whipple 10 m, and Fermi-LAT to cover the gamma-ray range from 0.1 GeV to 20 TeV; RXTE and Swift to cover wavelengths from UV to hard X-rays; and GASP-WEBT, which provides coverage of radio and optical wavelengths. Optical polarization measurements were provided for a fraction of the campaign by the Steward and St. Petersburg observatories. We evaluate the variability of the source and interband correlations, the gamma-ray flaring activity occurring in May 2009, and interpret the results within two synchrotron self-Compton (SSC) scenarios. Methods. The multiband variability observed during the full campaign is addressed in terms of the fractional variability, and the possible correlations are studied by calculating the discrete correlation function for each pair of energy bands where the significance was evaluated with dedicated Monte Carlo simulations. The space of SSC model parameters is probed following a dedicated grid-scan strategy, allowing for a wide range of models to be tested and offering a study of the degeneracy of model-to-data agreement in the individual model parameters, hence providing a less biased interpretation than the "single-curve SSC model adjustment" typically reported in the literature. Results. We find an increase in the fractional variability with energy, while no significant interband correlations of flux changes are found on the basis of the acquired data set. The SSC model grid-scan shows that the flaring activity around May 22 cannot be modeled adequately with a one-zone SSC scenario (using an electron energy distribution with two breaks), while it can be suitably described within a two (independent) zone SSC scenario. Here, one zone is responsible for the quiescent emission from the averaged 4.5-month observing period, while the other one, which is spatially separated from the first, dominates the flaring emission occurring at X-rays and very-high-energy (> 100 GeV, VHE) gamma-rays. The flaring activity from May 1, which coincides with a rotation of the electric vector polarization angle (EVPA), cannot be satisfactorily reproduced by either a one-zone or a two-independent-zone SSC model, yet this is partially affected by the lack of strictly simultaneous observations and the presence of large flux changes on sub-hour timescales (detected at VHE gamma rays). Conclusions. The higher variability in the VHE emission and lack of correlation with the X-ray emission indicate that, at least during the 4.5-month observing campaign in 2009, the highest energy (and most variable) electrons that are responsible for the VHE gamma rays do not make a dominant contribution to the similar to 1 keV emission. Alternatively, there could be a very variable component contributing to the VHE gamma-ray emission in addition to that coming from the SSC scenario. The studies with our dedicated SSC grid-scan show that there is some degeneracy in both the one-zone and the two-zone SSC scenarios probed, with several combinations of model parameters yielding a similar model-to-data agreement, and some parameters better constrained than others. The observed gamma-ray flaring activity, with the EVPA rotation coincident with the first gamma-ray flare, resembles those reported previously for low frequency peaked blazars, hence suggesting that there are many similarities in the flaring mechanisms of blazars with different jet properties.},
  language  = {en}
}
@article{AldorettaStLouisRichardsonetal.2016,
  author    = {Aldoretta, E. J. and St-Louis, N. and Richardson, N. D. and Moffat, Anthony F. J. and Eversberg, T. and Hill, G. M. and Shenar, Tomer and Artigau, E. and Gauza, B. and Knapen, J. H. and Kubat, Jiř{\´i} and Kubatova, Brankica and Maltais-Tariant, R. and Munoz, M. and Pablo, H. and Ramiaramanantsoa, T. and Richard-Laferriere, A. and Sablowski, D. P. and Simon-Diaz, S. and St-Jean, L. and Bolduan, F. and Dias, F. M. and Dubreuil, P. and Fuchs, D. and Garrel, T. and Grutzeck, G. and Hunger, T. and Kuesters, D. and Langenbrink, M. and Leadbeater, R. and Li, D. and Lopez, A. and Mauclaire, B. and Moldenhawer, T. and Potter, M. and dos Santos, E. M. and Schanne, L. and Schmidt, J. and Sieske, H. and Strachan, J. and Stinner, E. and Stinner, P. and Stober, B. and Strandbaek, K. and Syder, T. and Verilhac, D. and Waldschlaeger, U. and Weiss, D. and Wendt, A.},
  title     = {An extensive spectroscopic time series of three Wolf-Rayet stars - I. The lifetime of large-scale structures in the wind of WR 134},
  series = {Monthly notices of the Royal Astronomical Society},
  volume    = {460},
  journal   = {Monthly notices of the Royal Astronomical Society},
  publisher = {Oxford Univ. Press},
  address   = {Oxford},
  issn      = {0035-8711},
  doi       = {10.1093/mnras/stw1188},
  pages     = {3407 -- 3417},
  year      = {2016},
  abstract  = {During the summer of 2013, a 4-month spectroscopic campaign took place to observe the variabilities in three Wolf-Rayet stars. The spectroscopic data have been analysed for WR 134 (WN6b), to better understand its behaviour and long-term periodicity, which we interpret as arising from corotating interaction regions (CIRs) in the wind. By analysing the variability of the He ii lambda 5411 emission line, the previously identified period was refined to P = 2.255 +/- 0.008 (s.d.) d. The coherency time of the variability, which we associate with the lifetime of the CIRs in the wind, was deduced to be 40 +/- 6 d, or similar to 18 cycles, by cross-correlating the variability patterns as a function of time. When comparing the phased observational grey-scale difference images with theoretical grey-scales previously calculated from models including CIRs in an optically thin stellar wind, we find that two CIRs were likely present. A separation in longitude of Delta I center dot a parts per thousand integral 90A degrees was determined between the two CIRs and we suggest that the different maximum velocities that they reach indicate that they emerge from different latitudes. We have also been able to detect observational signatures of the CIRs in other spectral lines (C iv lambda lambda 5802,5812 and He i lambda 5876). Furthermore, a DAC was found to be present simultaneously with the CIR signatures detected in the He i lambda 5876 emission line which is consistent with the proposed geometry of the large-scale structures in the wind. Small-scale structures also show a presence in the wind, simultaneously with the larger scale structures, showing that they do in fact co-exist.},
  language  = {en}
}
@article{ArcherBarnackaBeilickeetal.2014,
  author    = {Archer, A. and Barnacka, Anna and Beilicke, M. and Benbow, W. and Berger, K. and Bird, R. and Biteau, Jonathan and Buckley, J. H. and Bugaev, V. and Byrum, K. and Cardenzana, J. V. and Cerruti, M. and Chen, W. and Chen, Xiaoming and Ciupik, L. and Connolly, M. P. and Cui, W. and Dickinson, H. J. and Dumm, J. and Eisch, J. D. and Falcone, A. and Federici, Simone and Feng, Q. and Finley, J. P. and Fleischhack, H. and Fortson, L. and Furniss, A. and Galante, N. and Griffin, S. and Griffiths, S. T. and Grube, J. and Gyuk, G. and Hakansson, Nils and Hanna, D. and Holder, J. and Hughes, G. and Johnson, C. A. and Kaaret, P. and Kar, P. and Kertzman, M. and Khassen, Y. and Kieda, D. and Krawczynski, H. and Kumar, S. and Lang, M. J. and Maier, G. and McArthur, S. and McCann, A. and Meagher, K. and Moriarty, P. and Mukherjee, R. and Nieto, D. and Ong, R. A. and Otte, A. N. and Park, N. and Perkins, J. S. and Pohl, Manuela and Popkow, A. and Prokoph, H. and Pueschel, Elisa and Quinn, J. and Ragan, K. and Rajotte, J. and Reyes, L. C. and Reynolds, P. T. and Richards, G. T. and Roache, E. and Sembroski, G. H. and Shahinyan, K. and Smith, A. W. and Staszak, D. and Telezhinsky, Igor O. and Tucci, J. V. and Tyler, J. and Varlotta, A. and Vincent, S. and Wakely, S. P. and Weinstein, A. and Welsing, R. and Wilhelm, Alina and Williams, D. A. and Zajczyk, A. and Zitzer, B.},
  title     = {Very-high energy observations of the galactic center region by veritas IN 2010-2012},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {790},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  number    = {2},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0004-637X},
  doi       = {10.1088/0004-637X/790/2/149},
  pages     = {9},
  year      = {2014},
  abstract  = {The Galactic center is an interesting region for high-energy (0.1-100 GeV) and very-high-energy (E > 100 GeV) gamma-ray observations. Potential sources of GeV/TeV gamma-ray emission have been suggested, e.g., the accretion of matter onto the supermassive black hole, cosmic rays from a nearby supernova remnant (e.g., Sgr A East), particle acceleration in a plerion, or the annihilation of dark matter particles. The Galactic center has been detected by EGRET and by Fermi/LAT in the MeV/GeV energy band. At TeV energies, the Galactic center was detected with moderate significance by the CANGAROO and Whipple 10 m telescopes and with high significance by H.E.S.S., MAGIC, and VERITAS. We present the results from three years of VERITAS observations conducted at large zenith angles resulting in a detection of the Galactic center on the level of 18 standard deviations at energies above similar to 2.5 TeV. The energy spectrum is derived and is found to be compatible with hadronic, leptonic, and hybrid emission models discussed in the literature. Future, more detailed measurements of the high-energy cutoff and better constraints on the high-energy flux variability will help to refine and/or disentangle the individual models.},
  language  = {en}
}
@article{DenkerKuckeinVermaetal.2018,
  author    = {Denker, Carsten and Kuckein, Christoph and Verma, Meetu and Manrique Gonzalez, Sergio Javier Gonzalez and Diercke, Andrea and Enke, Harry and Klar, Jochen and Balthasar, Horst and Louis, Rohan E. and Dineva, Ekaterina Ivanova},
  title     = {High-cadence Imaging and Imaging Spectroscopy at the GREGOR Solar Telescope-A Collaborative Research Environment for High-resolution Solar Physics},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Supplement series},
  volume    = {236},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Supplement series},
  number    = {1},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0067-0049},
  doi       = {10.3847/1538-4365/aab773},
  pages     = {12},
  year      = {2018},
  abstract  = {In high-resolution solar physics, the volume and complexity of photometric, spectroscopic, and polarimetric ground-based data significantly increased in the last decade, reaching data acquisition rates of terabytes per hour. This is driven by the desire to capture fast processes on the Sun and the necessity for short exposure times "freezing" the atmospheric seeing, thus enabling ex post facto image restoration. Consequently, large-format and high-cadence detectors are nowadays used in solar observations to facilitate image restoration. Based on our experience during the "early science" phase with the 1.5 m GREGOR solar telescope (2014-2015) and the subsequent transition to routine observations in 2016, we describe data collection and data management tailored toward image restoration and imaging spectroscopy. We outline our approaches regarding data processing, analysis, and archiving for two of GREGOR's post-focus instruments (see http://gregor.aip.de), i.e., the GREGOR Fabry-P{\´e}rot Interferometer (GFPI) and the newly installed High-Resolution Fast Imager (HiFI). The heterogeneous and complex nature of multidimensional data arising from high-resolution solar observations provides an intriguing but also a challenging example for "big data" in astronomy. The big data challenge has two aspects: (1) establishing a workflow for publishing the data for the whole community and beyond and (2) creating a collaborative research environment (CRE), where computationally intense data and postprocessing tools are colocated and collaborative work is enabled for scientists of multiple institutes. This requires either collaboration with a data center or frameworks and databases capable of dealing with huge data sets based on virtual observatory (VO) and other community standards and procedures.},
  language  = {en}
}
@article{GonzalezManriqueKuckeinColladosetal.2018,
  author    = {Gonzalez Manrique, Sergio Javier and Kuckein, Christoph and Collados, M. and Denker, Carsten and Solanki, S. K. and Gomory, P. and Verma, Meetu and Balthasar, H. and Lagg, A. and Diercke, Andrea},
  title     = {Temporal evolution of arch filaments as seen in He I 10 830 angstrom},
  series = {Astronomy and astrophysics : an international weekly journal},
  volume    = {617},
  journal   = {Astronomy and astrophysics : an international weekly journal},
  publisher = {EDP Sciences},
  address   = {Les Ulis},
  issn      = {1432-0746},
  doi       = {10.1051/0004-6361/201832684},
  pages     = {11},
  year      = {2018},
  abstract  = {Aims. We study the evolution of an arch filament system (AFS) and of its individual arch filaments to learn about the processes occurring in them. Methods. We observed the AFS at the GREGOR solar telescope on Tenerife at high cadence with the very fast spectroscopic mode of the GREGOR Infrared Spectrograph (GRIS) in the He I 10 830 angstrom spectral range. The He I triplet profiles were fitted with analytic functions to infer line-of-sight (LOS) velocities to follow plasma motions within the AFS. Results. We tracked the temporal evolution of an individual arch filament over its entire lifetime, as seen in the He I 10 830 angstrom triplet. The arch filament expanded in height and extended in length from 13 ' to 21 '. The lifetime of this arch filament is about 30 min. About 11 min after the arch filament is seen in He I, the loop top starts to rise with an average Doppler velocity of 6 km s(-1). Only two minutes later, plasma drains down with supersonic velocities towards the footpoints reaching a peak velocity of up to 40 km s(-1) in the chromosphere. The temporal evolution of He I 10 830 angstrom profiles near the leading pore showed almost ubiquitous dual red components of the He I triplet, indicating strong downflows, along with material nearly at rest within the same resolution element during the whole observing time.},
  language  = {en}
}
@article{GonzalezManriqueKuckeinPastorYabaretal.2016,
  author    = {Gonzalez Manrique, Sergio Javier and Kuckein, Christoph and Pastor Yabar, A. and Collados Vera, M. and Denker, Carsten and Fischer, C. E. and G{\"o}m{\"o}ry, P. and Diercke, Andrea and Gonzalez, N. Bello and Schlichenmaier, R. and Balthasar, H. and Berkefeld, T. and Feller, A. and Hoch, S. and Hofmann, A. and Kneer, F. and Lagg, A. and Nicklas, H. and Orozco Suarez, D. and Schmidt, D. and Schmidt, W. and Sigwarth, M. and Sobotka, M. and Solanki, S. K. and Soltau, D. and Staude, J. and Strassmeier, Klaus G. and Verma, Meetu and Volkmer, R. and von der L{\"u}he, O. and Waldmann, T.},
  title     = {Fitting peculiar spectral profiles in He I 10830 angstrom absorption features},
  series = {Astronomische Nachrichten = Astronomical notes},
  volume    = {337},
  journal   = {Astronomische Nachrichten = Astronomical notes},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {0004-6337},
  doi       = {10.1002/asna.201512433},
  pages     = {1057 -- 1063},
  year      = {2016},
  abstract  = {The new generation of solar instruments provides better spectral, spatial, and temporal resolution for a better understanding of the physical processes that take place on the Sun. Multiple-component profiles are more commonly observed with these instruments. Particularly, the He i 10830 triplet presents such peculiar spectral profiles, which give information on the velocity and magnetic fine structure of the upper chromosphere. The purpose of this investigation is to describe a technique to efficiently fit the two blended components of the He i 10830 triplet, which are commonly observed when two atmospheric components are located within the same resolution element. The observations used in this study were taken on 2015 April 17 with the very fast spectroscopic mode of the GREGOR Infrared Spectrograph (GRIS) attached to the 1.5-m GREGOR solar telescope, located at the Observatorio del Teide, Tenerife, Spain. We apply a double-Lorentzian fitting technique using Levenberg-Marquardt least-squares minimization. This technique is very simple and much faster than inversion codes. Line-of-sight Doppler velocities can be inferred for a whole map of pixels within just a few minutes. Our results show sub-and supersonic downflow velocities of up to 32 km s(-1) for the fast component in the vicinity of footpoints of filamentary structures. The slow component presents velocities close to rest. (C) 2016 WILEY-VCH Verlag GmbH\& Co. KGaA, Weinheim},
  language  = {en}
}
@article{HammPelivanGrottetal.2020,
  author    = {Hamm, Maximilian and Pelivan, Ivanka and Grott, Matthias and de Wiljes, Jana},
  title     = {Thermophysical modelling and parameter estimation of small solar system bodies via data assimilation},
  series = {Monthly notices of the Royal Astronomical Society},
  volume    = {496},
  journal   = {Monthly notices of the Royal Astronomical Society},
  number    = {3},
  publisher = {Oxford Univ. Press},
  address   = {Oxford},
  issn      = {0035-8711},
  doi       = {10.1093/mnras/staa1755},
  pages     = {2776 -- 2785},
  year      = {2020},
  abstract  = {Deriving thermophysical properties such as thermal inertia from thermal infrared observations provides useful insights into the structure of the surface material on planetary bodies. The estimation of these properties is usually done by fitting temperature variations calculated by thermophysical models to infrared observations. For multiple free model parameters, traditional methods such as least-squares fitting or Markov chain Monte Carlo methods become computationally too expensive. Consequently, the simultaneous estimation of several thermophysical parameters, together with their corresponding uncertainties and correlations, is often not computationally feasible and the analysis is usually reduced to fitting one or two parameters. Data assimilation (DA) methods have been shown to be robust while sufficiently accurate and computationally affordable even for a large number of parameters. This paper will introduce a standard sequential DA method, the ensemble square root filter, for thermophysical modelling of asteroid surfaces. This method is used to re-analyse infrared observations of the MARA instrument, which measured the diurnal temperature variation of a single boulder on the surface of near-Earth asteroid (162173) Ryugu. The thermal inertia is estimated to be 295 +/- 18 Jm(-2) K-1 s(-1/2), while all five free parameters of the initial analysis are varied and estimated simultaneously. Based on this thermal inertia estimate the thermal conductivity of the boulder is estimated to be between 0.07 and 0.12,Wm(-1) K-1 and the porosity to be between 0.30 and 0.52. For the first time in thermophysical parameter derivation, correlations and uncertainties of all free model parameters are incorporated in the estimation procedure that is more than 5000 times more efficient than a comparable parameter sweep.},
  language  = {en}
}
@phdthesis{Hildebrandt2015,
  author    = {Hildebrandt, Dominik},
  title     = {The HI Lyman-alpha opacity at redshift 2.7 < z < 3.6},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-78355},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xiv, 292},
  year      = {2015},
  abstract  = {Most of the baryonic matter in the Universe resides in a diffuse gaseous phase in-between galaxies consisting mostly of hydrogen and helium. This intergalactic medium (IGM) is distributed in large-scale filaments as part of the overall cosmic web. The luminous extragalactic objects that we can observe today, such as galaxies and quasars, are surrounded by the IGM in the most dense regions within the cosmic web. The radiation of these objects contributes to the so-called ultraviolet background (UVB) which keeps the IGM highly ionized ever since the epoch of reionization. Measuring the amount of absorption due to intergalactic neutral hydrogen (HI) against extragalactic background sources is a very useful tool to constrain the energy input of ionizing sources into the IGM. Observations suggest that the HI Lyman-alpha effective optical depth, τ_eff, decreases with decreasing redshift, which is primarily due to the expansion of the Universe. However, some studies find a smaller value of the effective optical depth than expected at the specific redshift z~3.2, possibly related to the complete reionization of helium in the IGM and a hardening of the UVB. The detection and possible cause of a decrease in τ_eff at z~3.2 is controversially debated in the literature and the observed features need further explanation. To better understand the properties of the mean absorption at high redshift and to provide an answer for whether the detection of a τ_eff feature is real we study 13 high-resolution, high signal-to-noise ratio quasar spectra observed with the Ultraviolet and Visual Echelle Spectrograph (UVES) at the Very Large Telescope (VLT). The redshift evolution of the effective optical depth, τ_eff(z), is measured in the redshift range 2.7≤z≤3.6. The influence of metal absorption features is removed by performing a comprehensive absorption-line-fitting procedure. In the first part of the thesis, a line-parameter analysis of the column density, N, and Doppler parameter, b, of ≈7500 individually fitted absorption lines is performed. The results are in good agreement with findings from previous surveys. The second (main) part of this thesis deals with the analysis of the redshift evolution of the effective optical depth. The τ_eff measurements vary around the empirical power law τ_eff(z)~(1+z)^(γ+1) with γ=2.09±0.52. The same analysis as for the observed spectra is performed on synthetic absorption spectra. From a comparison between observed and synthetic spectral data it can be inferred that the uncertainties of the τ_eff values are likely underestimated and that the scatter is probably caused by high-column-density absorbers with column densities in the range 15≤logN≤17. In the real Universe, such absorbers are rarely observed, however. Hence, the difference in τ_eff from different observational data sets and absorption studies is most likely caused by cosmic variance. If, alternatively, the disagreement between such data is a result of an too optimistic estimate of the (systematic) errors, it is also possible that all τ_eff measurements agree with a smooth evolution within the investigated redshift range. To explore in detail the different analysis techniques of previous studies an extensive literature comparison to the results of this work is presented in this thesis. Although a final explanation for the occurrence of the τ_eff deviation in different studies at z~3.2 cannot be given here, our study, which represents the most detailed line-fitting analysis of its kind performed at the investigated redshifts so far, represents another important benchmark for the characterization of the HI Ly-alpha effective optical depth at high redshift and its indicated unusual behavior at z~3.2.},
  language  = {en}
}
@article{HusserKamannDreizleretal.2016,
  author    = {Husser, Tim-Oliver and Kamann, Sebastian and Dreizler, Stefan and Wendt, Martin and Wulff, Nina and Bacon, Roland and Wisotzki, Lutz and Brinchmann, Jarle and Weilbacher, Peter Michael and Roth, Martin M. and Monreal-Ibero, Ana},
  title     = {MUSE crowded field 3D spectroscopy of over 12 000 stars in the globular cluster NGC 6397 I. The first comprehensive HRD of a globular cluster},
  series = {Nucleic acids research},
  volume    = {588},
  journal   = {Nucleic acids research},
  publisher = {EDP Sciences},
  address   = {Les Ulis},
  issn      = {1432-0746},
  doi       = {10.1051/0004-6361/201526949},
  pages     = {14},
  year      = {2016},
  abstract  = {Aims. We demonstrate the high multiplex advantage of crowded field 3D spectroscopy with the new integral field spectrograph MUSE by means of a spectroscopic analysis of more than 12 000 individual stars in the globular cluster NGC 6397. Methods. The stars are deblended with a point spread function fitting technique, using a photometric reference catalogue from HST as prior, including relative positions and brightnesses. This catalogue is also used for a first analysis of the extracted spectra, followed by an automatic in-depth analysis via a full-spectrum fitting method based on a large grid of PHOENIX spectra. Results. We analysed the largest sample so far available for a single globular cluster of 18 932 spectra from 12 307 stars in NGC 6397. We derived a mean radial velocity of v(rad) = 17.84 +/- 0.07 km s(-1) and a mean metallicity of [Fe/H] = -2.120 +/- 0.002, with the latter seemingly varying with temperature for stars on the red giant branch (RGB). We determine Teff and [Fe/H] from the spectra, and log g from HST photometry. This is the first very comprehensive Hertzsprung-Russell diagram (HRD) for a globular cluster based on the analysis of several thousands of stellar spectra, ranging from the main sequence to the tip of the RGB. Furthermore, two interesting objects were identified; one is a post-AGB star and the other is a possible millisecond-pulsar companion.},
  language  = {en}
}
@article{MorettiClementiniMarconietal.2016,
  author    = {Moretti, M. I. and Clementini, Gisella and Marconi, V. Ripepi M. and Rubele, S. and Cioni, Maria-Rosa L. and Muraveva, T. and Groenewegen, M. A. T. and Cross, N. J. G. and Ivanov, V. D. and Piatti, A. E. and de Grijs, Richard},
  title     = {The VMC survey - XX. Identification of new Cepheids in the Small Magellanic Cloud},
  series = {Monthly notices of the Royal Astronomical Society},
  volume    = {459},
  journal   = {Monthly notices of the Royal Astronomical Society},
  publisher = {Oxford Univ. Press},
  address   = {Oxford},
  issn      = {0035-8711},
  doi       = {10.1093/mnras/stw716},
  pages     = {1687 -- 1697},
  year      = {2016},
  abstract  = {We present K-s-band light curves for 299 Cepheids in the Small Magellanic Cloud (SMC) of which 288 are new discoveries that we have identified using multi-epoch near-infrared photometry obtained by the VISTA survey of the Magellanic Clouds system (VMC). The new Cepheids have periods in the range from 0.34 to 9.1 d and cover the magnitude interval 12.9 <= currency sign < K-s > <= currency sign 17.6 mag. Our method was developed using variable stars previously identified by the optical microlensing survey OGLE. We focus on searching new Cepheids in external regions of the SMC for which complete VMC K-s-band observations are available and no comprehensive identification of different types of variable stars from other surveys exists yet.},
  language  = {en}
}