Introduction

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Ejecta Evolution Following a Planned Impact into an Asteroid: The First Five Weeks

The impact of the DART spacecraft into Dimorphos, moon of the asteroid Didymos, changed Dimorphos' orbit substantially, largely from the ejection of material. We present results from twelve Earth-based facilities involved in a world-wide campaign to monitor the brightness and morphology of the ejecta in the first 35 days after impact. After an initial brightening of ~1.4 magnitudes, we find consistent dimming rates of 0.11-0.12 magnitudes/day in the first week, and 0.08-0.09 magnitudes/day over the entire study period. The system returned to its pre-impact brightness 24.3-25.3 days after impact through the primary ejecta tail remained. The dimming paused briefly eight days after impact, near in time to the appearance of the second tail. This was likely due to a secondary release of material after re-impact of a boulder released in the initial impact, through movement of the primary ejecta through the aperture likely played a role.Comment: 16 pages, 5 Figures, accepted in the Astrophysical Journal Letters (ApJL) on October 16, 202

Ejecta Evolution Following a Planned Impact into an Asteroid: The First Five Weeks

The impact of the Double Asteroid Redirection Test spacecraft into Dimorphos, moon of the asteroid Didymos, changed Dimorphos’s orbit substantially, largely from the ejection of material. We present results from 12 Earth-based facilities involved in a world-wide campaign to monitor the brightness and morphology of the ejecta in the first 35 days after impact. After an initial brightening of ∼1.4 mag, we find consistent dimming rates of 0.11–0.12 mag day−1 in the first week, and 0.08–0.09 mag day−1 over the entire study period. The system returned to its pre-impact brightness 24.3–25.3 days after impact though the primary ejecta tail remained. The dimming paused briefly eight days after impact, near in time to the appearance of the second tail. This was likely due to a secondary release of material after re-impact of a boulder released in the initial impact, though movement of the primary ejecta through the aperture likely played a role

Realisierung optischer Filter unter Verwendung von Ringresonatoren mit integrierten Halbleiterlaserverstärker auf GaInAsP/InP

Eine Schlüsselkomponente in einem optischen Netzwerk ist das optische Filter. Es gibt mehrere Arten von optischen Filtern, zum Beispiel Bragg - Gitter, Dünnschichtfilter, arrayed waveguide gratings (AWGs). Ein optisches Filter, dass in den letzten Jahren in der integrierten Optik hervorgetreten ist und welches in dieser Arbeit entworfen und untersucht wird auf der Basis von GaInAsP / InP, ist der Ringresonator. Filter auf der Basis von Ringresonatoren benötigen keine Spiegel oder Gitter für die optische Rückkopplung und eigenen sich deshalb hervorragend für die monolithische Integration mit anderen Komponenten wie z. B. Laser und Photodetektoren. Ein Filter mit einem benötigten bestimmten Transmissionsverhalten kann mit Hilfe mehrfach seriell oder parallel gekoppelter Ringresonatoren erreicht werden. ANFORDERUNGEN: Die Herstellung von Ringresonatoren in der integrierten Optik erfordert niedrig dämpfende, stark geführte Wellenleiter für die Realisierung kleiner Krümmungsradien (R ~ 100 µm). Abstimmbarkeit ist essenziell für die Systemanwendung von optischen Filtern. Im Fall periodischer Filter, in unserem Fall Ringresonatoren, ist es wichtig das Transmissionsverhalten des Filters an ein bestimmtes Kanalraster anzupassen (z. B. ITU - Raster). Die Filtereigenschaften passiver Ringresonatoren werden durch die internen Verluste eingeschränkt. Die Integration eines optischen Halbleiterverstärkers (SOA) ermöglicht nicht nur die Kompensation der internen Verluste, sondern auch zusätzliche Funktionalität (z. B. Schaltbarkeit). HERGESTELLTE BAUELEMENTE: Passive einfache Ringresonatoren und Doppelringresonatoren im Materialsystem GaInAsP / InP in der Form von Stadien, gekoppelt an Multimodeinterferenzkoppler (MMI) oder an Kodirektionalkoppler mit Radien von R = 100 µm - 200 µm und einem freien Spektralbereich (FSR) von 50 GHz und 100 GHz und On-Off Verhältnissen von mehr als 20 dB wurden realisiert. Einfache Ringresonatoren und Dreifachringresonatoren mit integrierten optischen Halbleiterverstärkern (Verstärkerlänge = 100 µm - 800 µm), gekoppelt an zwei Eingangs- und Ausgangswellenleiter unter der Verwendung von Kodirektionalkopplern mit Radien von R = 100 µm - 800 µm werden präsentiert. Die internen Verluste werden vollständig durch die Halbleiterverstärker ausgeglichen und On-Off Verhältnisse für den Durchgangskanal sowie für den Dropkanal von mehr als 20 dB wurden erreicht. Die Ringresonatoren besitzen einen freien Spektralbereich von 12,5 GHz, 25 GHz and 50 GHz. Die Abstimmbarkeit auf eine bestimmte Wellenlänge sowie die Resonanzanpassung der Doppel- und Dreifachringresonatoren konnte mit Hilfe von integrierten Platinwiderständen erreicht werden. Das Transmissionsverhalten hängt sehr von der stärke der Interaktion der beteiligten Ringresonatoren untereinander und mit den verwendeten Kopplern ab. Eine Designregel wird beschrieben um ein quasi rechteckiges Transmissionsverhalten durch Verwendung von Doppel- und Dreifachringresonatoren zu erreichen. Das Verhalten der hergestellten Bauelemente wird hinsichtlich ihrer Einfügedämpfung, Polarisationsabhängigkeit, Funktionalität und Einsatzmöglichkeit analysiert.A key device in all-optical networks is the optical filter. There are different types of optical filters, for example, Bragg gratings, thin film filters, arrayed waveguide gratings (AWGs). An optical filter which has emerged in the last few years in integrated optics and which is designed and investigated on the basis of GaInAsP / InP in this thesis is the ring resonator filter. Ring resonator filters do not require facets or gratings for optical feedback and are thus particularly suited for monolithic integration with other components such as lasers and photodetectors for example. A required passband shape of ring resonator filters can be custom designed by the use of multiple serial or parallel coupled resonators. REQUIREMENTS: The realization of ring resonators in integrated optics requires low loss waveguides with a strong confinement to achieve low bending radii (R ~ 100 µm). Tuneability is essential for the system application of optical filters. In the case of periodic filters, in our case ring resonators, it is important to fit the transmission curve to the defined channel spacing (e.g. ITU-grid). The performance of passive ring resonators for filter applications is limited by internal losses. The incorporation of a semiconductor optical amplifier (SOA) enables additional functionality (e. g. switchability) including the compensation of internal losses. REALIZED DEVICES: Passive single and double ring resonators in the material system GaInAsP / InP in the form of racetracks, coupled to a multimode interference (MMI) coupler or a codirectional coupler (CC) with radii of R = 100 µm - 200 µm and free spectral ranges (FSRs) of 50 GHz and 100 GHz and on-off ratios of more than 20 dB are realized. Single and triple ring resonators with integrated SOAs (length = 100 µm - 800 µm), coupled to two input/output waveguides using codirectional couplers with radii of R = 100 µm - 800 µm are demonstrated. The ring losses are compensated by the SOA and an on-off ratio for the throughput and drop port of more than 20 dB is realized. The achieved free spectral range is 12.5 GHz, 25 GHz and 50 GHz. The tuning to a specific wavelength and the resonance matching of the double and triple ring resonators is demonstrated by using integrated Pt - resistors. The passband shape depends sensitively on the relative interactions between all resonators and the used couplers. In order to achieve a box-like filter response, a general design rule is developed for engineering definite filter shapes using double and triple coupled ring resonators. The performance of the devices is analyzed with respect to insertion loss, polarization dependence, functionality and application

Integrated ring resonators: a compendium

This book describes the current state of the art in integrated ring resonators, covering more than two decades in the development of this exciting device. It discusses in depth one of the most fascinating and versatile integrated optical filters, providing readers with a panoramic view spanning from design and simulation to implementation in various material systems. Written by authors with extensive experience in both academia and industry, this second edition offers a much-needed, major update as interest in integrated ring resonators undergoes a global revival. The new edition includes a comprehensive technological update, and a timely discussion of recent advances in new application areas, such as optofluidics and microfluidics, telecom operations and biosensors. This aptly named compendium is the ideal guide for researchers and engineers looking to review the field as a whole while exploring several of its possible and exciting future trajectories.

Integrated Ring Resonators A Compendium

his book describes the current state of the art in integrated ring resonators, covering more than two decades in the development of this exciting device. It discusses in depth one of the most fascinating and versatile integrated optical filters, providing readers with a panoramic view spanning from design and simulation to implementation in various material systems. Written by authors with extensive experience in both academia and industry, this second edition offers a much-needed, major update as interest in integrated ring resonators undergoes a global revival. The new edition includes a comprehensive technological update, and a timely discussion of recent advances in new application areas, such as optofluidics and microfluidics, telecom operations and biosensors. This aptly named compendium is the ideal guide for researchers and engineers looking to review the field as a whole while exploring several of its possible and exciting future trajectories

High-precision photometry by telescope defocusing - VII. The ultrashort period planet WASP-103

We present 17 transit light curves of the ultrashort period planetary system WASP-103, a strong candidate for the detection of tidally-induced orbital decay. We use these to establish a high-precision reference epoch for transit timing studies. The time of the reference transit mid-point is now measured to an accuracy of 4.8 s, versus 67.4 s in the discovery paper, aiding future searches for orbital decay. With the help of published spectroscopic measurements and theoretical stellar models, we determine the physical properties of the system to high precision and present a detailed error budget for these calculations. The planet has a Roche lobe filling factor of 0.58, leading to a significant asphericity; we correct its measured mass and mean density for this phenomenon. A high-resolution Lucky Imaging observation shows no evidence for faint stars close enough to contaminate the point spread function of WASP-103. Our data were obtained in the Bessell RI and the SDSS griz passbands and yield a larger planet radius at bluer optical wavelengths, to a confidence level of 7.3σ. Interpreting this as an effect of Rayleigh scattering in the planetary atmosphere leads to a measurement of the planetary mass which is too small by a factor of 5, implying that Rayleigh scattering is not the main cause of the variation of radius with wavelength.Publisher PDFPeer reviewe

A detailed census of variable stars in the globular cluster NGC 6333 (M9) from CCD differential photometry

We report CCD V and I time series photometry of the globular cluster NGC 6333 (M9). The technique of difference image analysis has been used, which enables photometric precision better than 0.05 mag for stars brighter than V ∼ 19.0 mag, even in the crowded central regions of the cluster. The high photometric precision has resulted in the discovery of two new RRc stars, three eclipsing binaries, seven long-term variables and one field RRab star behind the cluster. A detailed identification chart and equatorial coordinates are given for all the variable stars in the field of our images of the cluster. Our data together with the literature V-data obtained in 1994 and 1995 allowed us to refine considerably the periods for all RR Lyrae stars. The nature of the new variables is discussed. We argue that variable V12 is a cluster member and an Anomalous Cepheid. Secular period variations, double-mode pulsations and/or the Blazhko-like modulations in some RRc variables are addressed. Through the light-curve Fourier decomposition of 12 RR Lyrae stars we have calculated a mean metallicity of [Fe/H]ZW = −1.70 ± 0.01(statistical) ± 0.14(systematic) or [Fe/H]UVES = -1.67± 0.01(statistical) ± 0.19(systematic). Absolute magnitudes, radii and masses are also estimated for the RR Lyrae stars. A detailed search for SX Phe stars in the Blue Straggler region was conducted but none were discovered. If SX Phe exist in the cluster then their amplitudes must be smaller than the detection limit of our photometry. The colour–magnitude diagram has been corrected for heavy differential reddening using the detailed extinction map of the cluster of Alonso-García et al. This has allowed us to set the mean cluster distance from two independent estimates; from the RRab and RRc absolute magnitudes, we find 8.04 ± 0.19 and 7.88 ± 0.30 kpc, respectively.</p

Estimating the parameters of globular cluster M 30 (NGC 7099) from time-series photometry

Aims. We present the analysis of 26 nights of V and I time-series observations from 2011 and 2012 of the globular cluster M 30 (NGC 7099). We used our data to search for variable stars in this cluster and refine the periods of known variables; we then used our variable star light curves to derive values for the cluster's parameters. Methods. We used difference image analysis to reduce our data to obtain high-precision light curves of variable stars. We then estimated the cluster parameters by performing a Fourier decomposition of the light curves of RR Lyrae stars for which a good period estimate was possible. We also derive an estimate for the age of the cluster by fitting theoretical isochrones to our colour-magnitude diagram (CMD). Results. Out of 13 stars previously catalogued as variables, we find that only 4 are bona fide variables. We detect two new RR Lyrae variables, and confirm two additional RR Lyrae candidates from the literature. We also detect four other new variables, including an eclipsing blue straggler system, and an SX Phoenicis star. This amounts to a total number of confirmed variable stars in M 30 of 12. We perform Fourier decomposition of the light curves of the RR Lyrae stars to derive cluster parameters using empirical relations. We find a cluster metallicity [Fe/H]ZW = −2.01 ± 0.04, or [Fe/H]UVES = −2.11 ± 0.06, and a distance of 8.32 ± 0.20 kpc (using RR0 variables), 8.10 kpc (using one RR1 variable), and 8.35 ± 0.42 kpc (using our SX Phoenicis star detection in M 30). Fitting isochrones to the CMD, we estimate an age of 13.0 ± 1.0 Gyr for M 30.</p