334 research outputs found
Metal shearing energy absorber
A metal shearing energy absorber is described. The absorber is composed of a flat thin strip of metal which is pulled through a slot in a cutter member of a metal, harder than the metal of the strip. The slot's length, in the direction perpendicular to the pull direction, is less than the strip's width so that as the strip is pulled through the slot, its edges are sheared off, thereby absorbing some of the pulling energy. In one embodiment the cutter member is a flat plate of steel, while in another embodiment the cutter member is U-shaped with the slot at its base
Metal-shearing energy absorber
Device, consisting of tongue of thin aluminum alloy strip, pull tab, slotted steel plate which serves as cutter, and steel buckle, absorbs mechanical energy when its ends are subjected to tensile loading. Device is applicable as auxiliary shock absorbing anchor for automobile and airplane safety belts
Exclusion of Stellar Companions to Exoplanet Host Stars
Given the frequency of stellar multiplicity in the solar neighborhood, it is
important to study the impacts this can have on exoplanet properties and
orbital dynamics. There have been numerous imaging survey projects established
to detect possible low-mass stellar companions to exoplanet host stars. Here we
provide the results from a systematic speckle imaging survey of known exoplanet
host stars. In total, 71 stars were observed at 692~nm and 880~nm bands using
the Differential Speckle Survey Instrument (DSSI) at the Gemini-North
Observatory. Our results show that all but 2 of the stars included in this
sample have no evidence of stellar companions with luminosities down to the
detection and projected separation limits of our instrumentation. The
mass-luminosity relationship is used to estimate the maximum mass a stellar
companion can have without being detected. These results are used to discuss
the potential for further radial velocity follow-up and interpretation of
companion signals.Comment: 11 pages, 4 figures, 3 tables, accepted for publication in A
Stellar Companions to the Exoplanet Host Stars HD 2638 and HD 164509
An important aspect of searching for exoplanets is understanding the binarity of the host stars. It is particularly important, because nearly half of the solar-like stars within our own Milky Way are part of binary or multiple systems. Moreover, the presence of two or more stars within a system can place further constraints on planetary formation, evolution, and orbital dynamics. As part of our survey of almost a hundred host stars, we obtained images at 692 and 880 nm bands using the Differential Speckle Survey Instrument (DSSI) at the Gemini-North Observatory. From our survey, we detect stellar companions to HD 2638 and HD 164509. The stellar companion to HD 2638 has been previously detected, but the companion to HD 164509 is a newly discovered companion. The angular separation for HD 2638 is 0.512 ± 0farcs002 and for HD 164509 is 0.697 ± 0farcs002. This corresponds to a projected separation of 25.6 ± 1.9 au and 36.5 ± 1.9 au, respectively. By employing stellar isochrone models, we estimate the mass of the stellar companions of HD 2638 and HD 164509 to be 0.483 ± 0.007 M_⊙ and $0.416 ± 0.007, M_⊙, respectively, and their effective temperatures to be 3570 ± 8 K and 3450 ± 7 K, respectively. These results are consistent with the detected companions being late-type M dwarfs
Stellar companions to the exoplanet host stars HD 2638 and HD 164509
An important aspect of searching for exoplanets is understanding the binarity of the host stars. It is particularly important, because nearly half of the solar-like stars within our own Milky Way are part of binary or multiple systems. Moreover, the presence of two or more stars within a system can place further constraints on planetary formation, evolution, and orbital dynamics. As part of our survey of almost a hundred host stars, we obtained images at 692 and 880 nm bands using the Differential Speckle Survey Instrument (DSSI) at the Gemini-North Observatory. From our survey, we detect stellar companions to HD-2638 and HD-164509. The stellar companion to HD-2638 has been previously detected, but the companion to HD-164509 is a newly discovered companion. The angular separation for HD-2638 is 0.512±0 002 and for HD-164509 is 0.697 0. 00 ' 2. This corresponds to a projected separation of 25.6±1.9 au and 36.5±1.9 au, respectively. By employing stellar isochrone models, we estimate the mass of the stellar companions of HD-2638 and HD-164509 to be 0.483±0.007-Me and 0.416 0.007 M, respectively, and their effective temperatures to be 3570±8K and 3450±7K, respectively. These results are consistent with the detected companions being late-type M dwarfs
Revisiting the warm sub-Saturn TOI-1710b
The Transiting Exoplanet Survey Satellite (TESS) provides a continuous suite
of new planet candidates that need confirmation and precise mass determination
from ground-based observatories. This is the case for the G-type star TOI-1710,
which is known to host a transiting sub-Saturn planet
(28.34.7) in a long-period orbit
(P=24.28\,d). Here we combine archival SOPHIE and new and archival HARPS-N
radial velocity data with newly available TESS data to refine the planetary
parameters of the system and derive a new mass measurement for the transiting
planet, taking into account the impact of the stellar activity on the mass
measurement. We report for TOI-1710b a radius of
5.150.12, a mass of
18.44.5, and a mean bulk density of
0.730.18, which are consistent at
1.2, 1.5, and 0.7, respectively, with previous
measurements. Although there is not a significant difference in the final mass
measurement, we needed to add a Gaussian process component to successfully fit
the radial velocity dataset. This work illustrates that adding more
measurements does not necessarily imply a better mass determination in terms of
precision, even though they contribute to increasing our full understanding of
the system. Furthermore, TOI-1710b joins an intriguing class of planets with
radii in the range 4-8 that have no counterparts in the
Solar System. A large gaseous envelope and a bright host star make TOI-1710b a
very suitable candidate for follow-up atmospheric characterization.Comment: Accepted for publication in A&A. 21 pages, 14 figure
BOREAS – a new MAX-DOAS profile retrieval algorithm for aerosols and trace gases
We present a new MAX-DOAS profiling algorithm for aerosols and trace gases,
BOREAS, which utilizes an iterative solution method including Tikhonov
regularization and the optimal estimation technique. The aerosol profile
retrieval is based on a novel approach in which the absorption depth of
O4 is directly used in order to retrieve extinction coefficient
profiles instead of the commonly used perturbation theory method. The
retrieval of trace gases is done with the frequently used optimal estimation
method but significant improvements are presented on how to deal with wrongly
weighted a priori constraints and for scenarios in which the a priori profile
is inaccurate.
Performance tests are separated into two parts. First, we address the general
sensitivity of the retrieval to the example of synthetic data calculated with
the radiative transfer model SCIATRAN. In the second part of the study, we
demonstrate BOREAS profiling accuracy by validating the results with the help of
ancillary measurements carried out during the CINDI-2 campaign in Cabauw, the
Netherlands, in 2016.
The synthetic sensitivity tests indicate that the regularization between
measurement and a priori constraints is insufficient when knowledge of the
true state of the atmosphere is poor. We demonstrate a priori pre-scaling and
extensive regularization tests as a tool for the optimization of retrieved
profiles. The comparison of retrieval results with in situ, ceilometer,
NO2 lidar, sonde and long-path DOAS measurements during the CINDI-2
campaign always shows high correlations with coefficients greater than 0.75.
The largest differences can be found in the morning hours, when the planetary
boundary layer is not yet fully developed and the concentration of trace
gases and aerosol, as a result of a low night-time boundary layer having
formed, is focused in a shallow, near-surface layer.</p
TESS Delivers Five New Hot Giant Planets Orbiting Bright Stars From The Full-Frame Images
We present the discovery and characterization of five hot and warm Jupiters—TOI-628 b (TIC 281408474; HD 288842), TOI-640 b (TIC 147977348), TOI-1333 b (TIC 395171208, BD+47 3521A), TOI-1478 b (TIC 409794137), and TOI-1601 b (TIC 139375960)—based on data from NASA\u27s Transiting Exoplanet Survey Satellite (TESS). The five planets were identified from the full-frame images and were confirmed through a series of photometric and spectroscopic follow-up observations by the TESS Follow-up Observing Program Working Group. The planets are all Jovian size (RP = 1.01–1.77 RJ) and have masses that range from 0.85 to 6.33 MJ. The host stars of these systems have F and G spectral types (5595 ≤ Teff ≤ 6460 K) and are all relatively bright (9.5 \u3c V \u3c 10.8, 8.2 \u3c K \u3c 9.3), making them well suited for future detailed characterization efforts. Three of the systems in our sample (TOI-640 b, TOI-1333 b, and TOI-1601 b) orbit subgiant host stars ( g \u3c 4.1). TOI-640 b is one of only three known hot Jupiters to have a highly inflated radius (RP \u3e 1.7 RJ, possibly a result of its host star\u27s evolution) and resides on an orbit with a period longer than 5 days. TOI-628 b is the most massive, hot Jupiter discovered to date by TESS with a measured mass of MJ and a statistically significant, nonzero orbital eccentricity of e = . This planet would not have had enough time to circularize through tidal forces from our analysis, suggesting that it might be remnant eccentricity from its migration. The longest-period planet in this sample, TOI-1478 b (P = 10.18 days), is a warm Jupiter in a circular orbit around a near-solar analog. NASA\u27s TESS mission is continuing to increase the sample of well-characterized hot and warm Jupiters, complementing its primary mission goals
OSIRIS – The scientific camera system onboard Rosetta
The Optical, Spectroscopic, and Infrared Remote Imaging System OSIRIS is the scientific camera system onboard the Rosetta spacecraft (Figure 1). The advanced high performance imaging system will be pivotal for the success of the Rosetta mission. OSIRIS will detect 67P/Churyumov-Gerasimenko from a distance of more than 106 km, characterise the comet shape and volume, its rotational state and find a suitable landing spot for Philae, the Rosetta lander. OSIRIS will observe the nucleus, its activity and surroundings down to a scale of ~2 cm px−1. The observations will begin well before the onset of cometary activity and will extend over months until the comet reaches perihelion. During the rendezvous episode of the Rosetta mission, OSIRIS will provide key information about the nature of cometary nuclei and reveal the physics of cometary activity that leads to the gas and dust coma.
OSIRIS comprises a high resolution Narrow Angle Camera (NAC) unit and a Wide Angle Camera (WAC) unit accompanied by three electronics boxes. The NAC is designed to obtain high resolution images of the surface of comet 7P/Churyumov-Gerasimenko through 12 discrete filters over the wavelength range 250–1000 nm at an angular resolution of 18.6 μrad px−1. The WAC is optimised to provide images of the near-nucleus environment in 14 discrete filters at an angular resolution of 101 μrad px−1. The two units use identical shutter, filter wheel, front door, and detector systems. They are operated by a common Data Processing Unit. The OSIRIS instrument has a total mass of 35 kg and is provided by institutes from six European countrie
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