In the first English-language history of the Berlin zoo, Gary Bruce traces the fascinating story of one of Germany's most popular cultural institutions, from its 19th century displays of "exotic" ...peoples to Nazi attempts to breed back long-extinct European cattle. As an institution with broad public reach, the zoo for more than 150 years shaped German views not only of the animal world, but of the human world far beyond Germany's borders.
Abstract
We present follow-up photometry and spectroscopy of ZTF J0328−1219, strengthening its status as a white dwarf exhibiting transiting planetary debris. Using TESS and Zwicky Transient Facility ...photometry, along with follow-up high-speed photometry from various observatories, we find evidence for two significant periods of variability at 9.937 and 11.2 hr. We interpret these as most likely the orbital periods of different debris clumps. Changes in the detailed dip structures within the light curves are observed on nightly, weekly, and monthly timescales, reminiscent of the dynamic behavior observed in the first white dwarf discovered to harbor a disintegrating asteroid, WD 1145+017. We fit previously published spectroscopy along with broadband photometry to obtain new atmospheric parameters for the white dwarf, with
M
⋆
= 0.731 ± 0.023
M
⊙
,
T
eff
= 7630 ± 140 K, and Ca/He = − 9.55 ± 0.12. With new high-resolution spectroscopy, we detect prominent and narrow Na D absorption features likely of circumstellar origin, with velocities 21.4 ± 1.0 km s
−1
blueshifted relative to atmospheric lines. We attribute the periodically modulated photometric signal to dusty effluents from small orbiting bodies such as asteroids or comets, but we are unable to identify the most likely material that is being sublimated, or otherwise ejected, as the environmental temperatures range from roughly 400 to 700 K.
WD 1145+017 is a unique white dwarf system that has a heavily polluted atmosphere, an infrared excess from a dust disk, numerous broad absorption lines from circumstellar gas, and changing transit ...features, likely from fragments of an actively disintegrating asteroid. Here, we present results from a large photometric and spectroscopic campaign with Hubble Space Telescope, Keck, Very Large Telescope (VLT), Spitzer, and many other smaller telescopes from 2015 to 2018. Somewhat surprisingly the ultraviolet (UV) transit depths are always shallower than those in the optical. We develop a model that can quantitatively explain the observed "bluing" and confirm the previous finding that: (1) the transiting objects, circumstellar gas, and white dwarf are all aligned along our line of sight; (2) the transiting object is blocking a larger fraction of the circumstellar gas than of the white dwarf itself. Because most circumstellar lines are concentrated in the UV, the UV flux appears to be less blocked compared to the optical during a transit, leading to a shallower UV transit. This scenario is further supported by the strong anticorrelation between optical transit depth and circumstellar line strength. We have yet to detect any wavelength-dependent transits caused by the transiting material around WD 1145+017.
Abstract
We report the discovery of a unique object of uncertain nature—but quite possibly a disintegrating asteroid or minor planet—orbiting one star of the widely separated binary TIC 400799224. We ...initially identified the system in data from TESS Sector 10 via an abnormally shaped fading event in the light curve (hereafter “dips”). Follow-up speckle imaging determined that TIC 400799224 is actually two stars of similar brightness at 0.″62 separation, forming a likely bound binary with projected separation of ∼300 au. We cannot yet determine which star in the binary is host to the dips in flux. ASAS-SN and Evryscope archival data show that there is a strong periodicity of the dips at ∼19.77 days, leading us to believe that an occulting object is orbiting the host star, though the duration, depth, and shape of the dips vary substantially. Statistical analysis of the ASAS-SN data shows that the dips only occur sporadically at a detectable threshold in approximately one out of every three to five transits, lending credence to the possibility that the occulter is a sporadically emitted dust cloud. The cloud is also fairly optically thick, blocking up to 37% or 75% of the light from the host star, depending on the true host. Further observations may allow for greater detail to be gleaned as to the origin and composition of the occulter, as well as to a determination of which of the two stars comprising TIC 400799224 is the true host star of the dips.
•We observed dwarf planet Ceres through the Dawn Framing Camera filters for 3years.•Albedos consistent with featureless spectrum, but values ∼10% higher than expected.•Ground-based FC color filter ...lightcurve data are consistent with HST albedo maps.•We found a correlation between 1.1-μm band depth and geometric albedo.•This suggests brighter areas on Ceres have absorption bands that are deeper.
The dwarf planet Ceres is likely differentiated similar to the terrestrial planets but with a water/ice dominated mantle and an aqueously altered crust. Detailed modeling of Ceres’ phase function has never been performed to understand its surface properties. The Dawn spacecraft began orbital science operations at the dwarf planet in April 2015. We observed Ceres with flight spares of the seven Dawn Framing Camera color filters mounted on ground-based telescopes over the course of three years to model its phase function versus wavelength. Our analysis shows that the modeled geometric albedos derived from both the IAU HG model and the Hapke model are consistent with a flat and featureless spectrum of Ceres, although the values are ∼10% higher than previous measurements. Our models also suggest a wavelength dependence of Ceres’ phase function. The IAU G-parameter and the Hapke single-particle phase function parameter, g, are both consistent with decreasing (shallower) phase slope with increasing wavelength. Such a wavelength dependence of phase function is consistent with reddening of spectral slope with increasing phase angle, or phase-reddening. This phase reddening is consistent with previous spectra of Ceres obtained at various phase angles archived in the literature, and consistent with the fact that the modeled geometric albedo spectrum of Ceres is the bluest of all spectra because it represents the spectrum at 0° phase angle. Ground-based FC color filter lightcurve data are consistent with HST albedo maps confirming that Ceres’ lightcurve is dominated by albedo and not shape. We detected a positive correlation between 1.1-μm absorption band depth and geometric albedo suggesting brighter areas on Ceres have absorption bands that are deeper. We did not see the “extreme” slope values measured by Perna et al. (Perna, D., et al. 2015. Astron. Astrophys. 575 (L1-6)), which they have attributed to “resurfacing episodes” on Ceres.
Abstract
This article employs the ‘second chapter’ of the history of daily life (Alltagsgeschichte) to examine grass-roots resistance to the communist system in the former East German district of ...Gransee. It has two primary goals. First, it posits a bridge between the two solitudes of ‘resistance’ history and ‘daily life’ history. Typically, historians of daily life have not examined resistance in East Germany, nor have historians of resistance used the methodology of the history of everyday life to investigate their subject. ‘Dictatorship’ and ‘daily life’ are not, however, mutually exclusive terms. Second, the article centres ‘place’ as an organizational concept for both resistance and daily life. What was idiosyncratic to a locality informed the limits and potential of resistance. Place also becomes a useful concept for distinguishing between resistance and opposition. Colonizing a public space in order to transmit one’s oppositional views immediately conveys an act into the resistance realm. This article therefore explores the key socio-economic factors in District Gransee from which resistance could arise and the many ways that East Germans used the spaces of everyday life, such as schools, train stations and pubs, to communicate their opposition to the East German system.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We report on a V = 11.2 early K dwarf, XO-2 (GSC 03413-00005), that hosts a R sub(P) = 0.98 plus or minus super(0) sub(0) super(.) sub(.) super(0) sub(0) super(3) sub(1) R sub(J), M sub(P) = 0.57 ...plus or minus 0.06 M sub(J) transiting extrasolar planet, XO-2b, with an orbital period of 2.615837 plus or minus 0.000005 days. XO-2 has high metallicity, Fe/H = 0.45 plus or minus 0.02, high proper motion, mu sub(lot) = 157 mas yr sub(-1), and a common proper motion stellar companion with 31 degree separation. The two stars are nearly identical twins, with very similar spectra and apparent magnitudes. Due to the high metallicity, these early K dwarf stars have a mass and radius close to solar, M unk = 0.98 plus or minus 0.02 M unk and R unk = 0.97 plus or minus super(0) sub(0) super(.) sub(.) super(0) sub(0) super(2) sub(1) R unk. The high proper motion of XO-2 results from an eccentric orbit (Galactic pericenter, R sub(pot) < 4 kpc) well confined to the Galactic disk (Z sub(max) similar to 100 pc). In addition, the phase-space position of XO-2 is near the Hercules dynamical stream, which points to an origin of XO-2 in the metal-rich, inner thin disk and subsequent dynamical scattering into the solar neighborhood. We describe an efficient Markov chain Monte Carlo algorithm for calculating the Bayesian posterior probability of the system parameters from a transit light curve.
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