352 research outputs found
The Chiastic Arrangement of the Lukan Temptation Narrative
What constitutes a chiasm is a debated area of research and more often neglected within biblical studies. In response to this, Craig Arnold Smith has produced a work that provides new insights into how to determine whether an author intentionally employs a chiasm. Working from Smith’s method, this paper argues that the Lukan temptation in the wilderness narrative is structured as a chiasm. It also demonstrates how the temptation functions to emphasize certain Lukan themes. Furthermore, it demonstrates that the chiasm of Luke 4:1–14a enhances the interpretive significance of the passage by revealing a literary function that has consequences for the reading of the entirety of Luke-Acts. These functions in turn validate the chiasm of Luke 4:1–14a, illustrating the value of Smith’s methodology
LRG-BEASTS III: Ground-based transmission spectrum of the gas giant orbiting the cool dwarf WASP-80
We have performed ground-based transmission spectroscopy of the hot Jupiter
orbiting the cool dwarf WASP-80 using the ACAM instrument on the William
Herschel Telescope (WHT) as part of the LRG-BEASTS programme. This is the third
paper of a ground-based transmission spectroscopy survey of hot Jupiters using
low-resolution grism spectrographs. We observed two transits of the planet and
have constructed transmission spectra spanning a wavelength range of
4640-8840A. Our transmission spectrum is inconsistent with a previously claimed
detection of potassium in WASP-80b's atmosphere, and is instead most consistent
with a haze. We also do not see evidence for sodium absorption at a resolution
of 100A.Comment: 11 pages, 9 figures. Accepted for publication in MNRA
Rayleigh scattering in the transmission spectrum of HAT-P-18b
We have performed ground-based transmission spectroscopy of the hot Jupiter
HAT-P-18b using the ACAM instrument on the William Herschel Telescope (WHT).
Differential spectroscopy over an entire night was carried out at a resolution
of using a nearby comparison star. We detect a bluewards slope
extending across our optical transmission spectrum which runs from 4750 to
9250\AA. The slope is consistent with Rayleigh scattering at the equilibrium
temperature of the planet (852K). We do not detect enhanced sodium absorption,
which indicates that a high-altitude haze is masking the feature and giving
rise to the Rayleigh slope. This is only the second discovery of a Rayleigh
scattering slope in a hot Jupiter atmosphere from the ground, and our study
illustrates how ground-based observations can provide transmission spectra with
precision comparable to the Hubble Space Telescope.Comment: 11 pages, 9 figures, accepted for publication in MNRA
High-energy environment of super-Earth 55 Cnc e I: Far-UV chromospheric variability as a possible tracer of planet-induced coronal rain
The irradiation of close-in planets by their star influences their evolution
and might be responsible for a population of ultra-short period planets eroded
to their bare core. In orbit around a bright, nearby G-type star, the
super-Earth 55 Cnc e offers the possibility to address these issues through UV
transit observations. We used the Hubble Space Telescope to observe the transit
in the FUV over 3 epochs in Apr. 2016, Jan. 2017, and Feb. 2017. These
observations reveal significant short- and long-term variability in 55 Cnc
chromospheric emission lines. In the last 2 epochs, we detected a larger flux
in the C III, Si III, and Si IV lines after the planet passed the approaching
quadrature, followed by a flux decrease in the Si IV doublet. In the second
epoch these variations are contemporaneous with flux decreases in the Si II and
C II doublet. All epochs show flux decreases in the N V doublet as well, albeit
at different orbital phases. These flux decreases are consistent with
absorption from optically thin clouds of gas, are mostly localized at low and
redshifted radial velocities in the star rest frame, and occur preferentially
before and during the transit. These 3 points make it unlikely that the
variations are purely stellar, yet we show that the occulting material is also
unlikely to originate from the planet. We tentatively propose that the motion
of 55 Cnc e at the fringes of the stellar corona leads to the formation of a
cool coronal rain. The inhomogeneity and temporal evolution of the stellar
corona would be responsible for the differences between the visits. Additional
variations are detected in the C II doublet in the first epoch and in the O I
triplet in all epochs with a different behavior that points toward intrinsic
stellar variability. Further observations at FUV wavelengths are required to
disentangle between star-planet interactions and the activity of the starComment: 22 pages, 20 figures, accepted for publication in A&
The Iliad’s big swoon: a case of innovation within the epic tradition
In book 5 of the Iliad Sarpedon suffers so greatly from a wound that his ‘‘ψυχή leaves him’. Rather than dying, however, Sarpedon lives to fight another day. This paper investigates the phrase τὸν δὲ λίπε ψυχή in extant archaic Greek poetry to gain a sense of its traditional referentiality and better assess the meaning of Sarpedon’s swoon. Finding that all other instances of the ψυχή leaving the body signify death, it suggests that the Iliad exploits a traditional unit of utterance to flag up the importance of Sarpedon to this version of the Troy story
LRG-BEASTS: Evidence for clouds in the transmission spectrum of HATS-46 b
We have performed low-resolution ground-based spectroscopy of HATS-46 b in
transmission, using the EFOSC2 instrument on the ESO New Technology Telescope
(NTT). HATS-46 b is a highly-inflated exoplanet that is a prime target for
transmission spectroscopy, having a Jupiter-like radius (0.95 R)
but a much lower mass (0.16 M). It orbits a G-type star with a
4.7 d period, giving an equilibrium temperature of 1100 K. We observed one
transit of HATS-46 b with the NTT, with the time-series spectra covering a
wavelength range of 3900 - 9000 Angstrom at a resolution of . We
achieved a remarkably precise transmission spectrum of 1.03 photon
noise, with a median uncertainty of ppm for Angstrom wide
bins, despite the relative faintness of the host star with . The transmission spectrum does not show strong absorption features and
retrievals favour a cloudy model, ruling out a clear atmosphere with
confidence. We also place a conservative upper limit on the sodium
abundance under the alternative scenario of a clear atmosphere. This is the
eighth planet in the LRG-BEASTS survey, which uses 4m-class telescopes such as
the NTT to obtain low-resolution transmission spectra of hot Jupiters with
precisions of around one atmospheric scale height.Comment: 10 pages, 7 figures, 4 tables, accepted for publication in MNRA
LRG-BEASTS: sodium absorption and Rayleigh scattering in the atmosphere of WASP-94A b using NTT/EFOSC2
Stars and planetary system
LRG-BEASTS: Ground-based Detection of Sodium and a Steep Optical Slope in the Atmosphere of the Highly Inflated Hot-Saturn WASP-21b
We present the optical transmission spectrum of the highly inflated
Saturn-mass exoplanet WASP-21b, using three transits obtained with the ACAM
instrument on the William Herschel Telescope through the LRG-BEASTS survey (Low
Resolution Ground-Based Exoplanet Atmosphere Survey using Transmission
Spectroscopy). Our transmission spectrum covers a wavelength range of 4635-9000
Angstrom, achieving an average transit depth precision of 197ppm compared to
one atmospheric scale height at 246ppm. We detect Na I absorption in a bin
width of 30 Angstrom, at >4 confidence, which extends over 100
Angstrom. We see no evidence of absorption from K I. Atmospheric retrieval
analysis of the scattering slope indicates it is too steep for Rayleigh
scattering from H, but is very similar to that of HD 189733b. The features
observed in our transmission spectrum cannot be caused by stellar activity
alone, with photometric monitoring of WASP-21 showing it to be an inactive
star. We therefore conclude that aerosols in the atmosphere of WASP-21b are
giving rise to the steep slope that we observe, and that WASP-21b is an
excellent target for infra-red observations to constrain its atmospheric
metallicity.Comment: Accepted for publication in MNRAS. 21 pages, 10 tables, 16 figure
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