scholarly journals Characterization of material around the centaur (2060) Chiron from a visible and near-infrared stellar occultation in 2011

2019 ◽  
Vol 491 (3) ◽  
pp. 3643-3654
Author(s):  
A A Sickafoose ◽  
A S Bosh ◽  
J P Emery ◽  
M J Person ◽  
C A Zuluaga ◽  
...  
Keyword(s):  
Near Infrared ◽  
Detailed Examination ◽  
Optical Data ◽  
Infrared Telescope ◽  
Nir Light ◽  
Spherical Diameter ◽  
Telescope Facility ◽  
Nasa Infrared Telescope Facility ◽  
Scattering Material

ABSTRACT The centaur (2060) Chiron exhibits outgassing behaviour and possibly hosts a ring system. On 2011 November 29, Chiron occulted a fairly bright star (R ∼ 15 mag) as observed from the 3-m NASA Infrared Telescope Facility (IRTF) on Mauna Kea and the 2-m Faulkes Telescope North (FTN) at Haleakala. Data were taken as visible wavelength images and simultaneous, low-resolution, near-infrared (NIR) spectra. Here, we present a detailed examination of the light-curve features in the optical data and an analysis of the NIR spectra. We place a lower limit on the spherical diameter of Chiron's nucleus of 160.2 ± 1.3 km. Sharp, narrow dips were observed between 280 and 360 km from the centre (depending on event geometry). For a central chord and assumed ring plane, the separated features are 298.5–302 and 308–310.5 km from the nucleus, with normal optical depth ∼0.5–0.9, and a gap of 9.1 ± 1.3 km. These features are similar in equivalent depth to Chariklo's inner ring. The absence of absorbing/scattering material near the nucleus suggests that these sharp dips are more likely to be planar rings than a shell of material. The region of relatively increased transmission is within the 1:2 spin-orbit resonance, consistent with the proposed clearing pattern for a non-axisymmetric nucleus. Characteristics of possible azimuthally incomplete features are presented, which could be transient, as well as a possible shell from ∼900–1500 km: future observations are needed for confirmation. There are no significant features in the NIR light curves, nor any correlation between optical features and NIR spectral slope.

scholarly journals The H 3 + ionosphere of Uranus: decades-long cooling and local-time morphology

2019 ◽  
Vol 377 (2154) ◽  
pp. 20180408 ◽  
Author(s):  
Henrik Melin ◽  
L. N. Fletcher ◽  
T. S. Stallard ◽  
S. Miller ◽  
L. M. Trafton ◽  
...  
Keyword(s):  
Local Time ◽  
Near Infrared ◽  
Molecular Ions ◽  
Upper Atmosphere ◽  
Infrared Observations ◽  
Infrared Telescope ◽  
Telescope Facility ◽  
Nasa Infrared Telescope Facility ◽  
Cooling Trend

The upper atmosphere of Uranus has been observed to be slowly cooling between 1993 and 2011. New analysis of near-infrared observations of emission from H 3 + obtained between 2012 and 2018 reveals that this cooling trend has continued, showing that the upper atmosphere has cooled for 27 years, longer than the length of a nominal season of 21 years. The new observations have offered greater spatial resolution and higher sensitivity than previous ones, enabling the characterization of the H 3 + intensity as a function of local time. These profiles peak between 13 and 15 h local time, later than models suggest. The NASA Infrared Telescope Facility iSHELL instrument also provides the detection of a bright H 3 + signal on 16 October 2016, rotating into view from the dawn sector. This feature is consistent with an auroral signal, but is the only of its kind present in this comprehensive dataset. This article is part of a discussion meeting issue ‘Advances in hydrogen molecular ions: H 3 + , H 5 + and beyond’.

scholarly journals Precise Near-Infrared Radial Velocities

2015 ◽  
Vol 10 (S314) ◽  
pp. 286-287
Author(s):  
Peter Plavchan ◽  
Peter Gao ◽  
Jonathan Gagne ◽  
Elise Furlan ◽  
Carolyn Brinkworth ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Near Infrared ◽  
M Dwarfs ◽  
Gas Cell ◽  
Methane Absorption ◽  
Infrared Telescope ◽  
Telescope Facility ◽  
Nasa Infrared Telescope Facility ◽  
Modeling Code

AbstractWe present the results of two 2.3 μm near-infrared (NIR) radial velocity (RV) surveys to detect exoplanets around 36 nearby and young M dwarfs. We use the CSHELL spectrograph (R ~ 46,000) at the NASA InfraRed Telescope Facility (IRTF), combined with an isotopic methane absorption gas cell for common optical path relative wavelength calibration. We have developed a sophisticated RV forward modeling code that accounts for fringing and other instrumental artifacts present in the spectra. With a spectral grasp of only 5 nm, we are able to reach long-term radial velocity dispersions of ~20–30 m s−1 on our survey targets.

Tuning the Electrochemical and Photophysical Properties of Osmium-Based Photoredox Catalysts

Synlett ◽  
2022 ◽  
Author(s):  
Eva Bednářová ◽  
Logan R. Beck ◽  
Tomislav Rovis ◽  
Samantha L. Goldschmid ◽  
Katherine Xie ◽  
...  
Keyword(s):  
Ground State ◽  
Emission Spectroscopy ◽  
Near Infrared ◽  
Photophysical Properties ◽  
Low Energy ◽  
Redox Potentials ◽  
Nir Light ◽  
Osmium Complexes ◽  
Absorption And Emission Spectroscopy

AbstractThe use of low-energy deep-red (DR) and near-infrared (NIR) light to excite chromophores enables catalysis to ensue across barriers such as materials and tissues. Herein, we report the detailed photophysical characterization of a library of OsII polypyridyl photosensitizers that absorb low-energy light. By tuning ligand scaffold and electron density, we access a range of synthetically useful excited state energies and redox potentials.1 Introduction1.1 Scope1.2 Measuring Ground-State Redox Potentials1.3 Measuring Photophysical Properties1.4 Synthesis of Osmium Complexes2 Properties of Osmium Complexes2.1 Redox Potentials of Os(L)2-Type Complexes2.2 Redox Potentials of Os(L)3-Type Complexes2.3 UV/Vis Absorption and Emission Spectroscopy3 Conclusions

A powerful new infrared array camera for the NASA Infrared Telescope Facility

1994 ◽  
Vol 3 (1-4) ◽  
pp. 239-242 ◽  
Author(s):  
Mark Shure ◽  
D. W. Toomey ◽  
John Rayner ◽  
P. Onaka ◽  
A. Denault ◽  
...  
Keyword(s):  
Infrared Telescope ◽  
Telescope Facility ◽  
Nasa Infrared Telescope Facility ◽  
Array Camera ◽  
Infrared Array ◽  
Infrared Telescope Facility

The NASA Infrared Telescope Facility Comet Halley monitoring program. II - Postperihelion results

1988 ◽  
Vol 96 ◽  
pp. 1971 ◽  
Author(s):  
A. T. Tokunaga ◽  
W. F. Golisch ◽  
D. M. Griep ◽  
C. D. Kaminski ◽  
M. S. Hanner
Keyword(s):  
Monitoring Program ◽  
Infrared Telescope ◽  
Telescope Facility ◽  
Nasa Infrared Telescope Facility ◽  
Comet Halley ◽  
Infrared Telescope Facility

NSFCAM: a new infrared array camera for the NASA Infrared Telescope Facility

1994 ◽  
Author(s):  
Mark A. Shure ◽  
Douglas W. Toomey ◽  
John T. Rayner ◽  
Peter M. Onaka ◽  
Anthony J. Denault
Keyword(s):  
Infrared Telescope ◽  
Telescope Facility ◽  
Nasa Infrared Telescope Facility ◽  
Array Camera ◽  
Infrared Array ◽  
Infrared Telescope Facility

scholarly journals SpeX: A Medium‐Resolution 0.8–5.5 Micron Spectrograph and Imager for the NASA Infrared Telescope Facility

2003 ◽  
Vol 115 (805) ◽  
pp. 362-382 ◽  
Author(s):  
J. T. Rayner ◽  
D. W. Toomey ◽  
P. M. Onaka ◽  
A. J. Denault ◽  
W. E. Stahlberger ◽  
...  
Keyword(s):  
Infrared Telescope ◽  
Medium Resolution ◽  
Telescope Facility ◽  
Nasa Infrared Telescope Facility ◽  
Infrared Telescope Facility

scholarly journals The NASA Infrared Telescope Facility (IRTF) 2023-2032

2021 ◽  
Vol 53 (4) ◽  
Author(s):  
John Rayner ◽  
Vishnu Reddy ◽  
Participants at the IRTF Future Directions Workshop
Keyword(s):  
Infrared Telescope ◽  
Telescope Facility ◽  
Nasa Infrared Telescope Facility ◽  
Infrared Telescope Facility

scholarly journals Variability of Jovian ion winds: an upper limit for enhanced Joule heating

2007 ◽  
Vol 25 (4) ◽  
pp. 847-853 ◽  
Author(s):  
M. B. Lystrup ◽  
S. Miller ◽  
T. Stallard ◽  
C. G. A. Smith ◽  
A. Aylward
Keyword(s):  
Joule Heating ◽  
Spatial Scales ◽  
Emission Spectra ◽  
Infrared Emission ◽  
Data Set ◽  
Infrared Telescope ◽  
Energy Inputs ◽  
Upper Limits ◽  
Telescope Facility ◽  
Nasa Infrared Telescope Facility

Abstract. It has been proposed that short-timescale fluctuations about the mean electric field can significantly increase the upper atmospheric energy inputs at Jupiter, which may help to explain the high observed thermospheric temperatures. We present data from the first attempt to detect such variations in the Jovian ionosphere. Line-of-sight ionospheric velocity profiles in the Southern Jovian auroral/polar region are shown, derived from the Doppler shifting of H3+ infrared emission spectra. These data were recently obtained from the high-resolution CSHELL spectrometer at the NASA Infrared Telescope Facility. We find that there is no variability within this data set on timescales of the order of one minute and spatial scales of 640 km, putting upper limits on the timescales of fluctuations that would be needed to enhance Joule heating.

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