scholarly journals Direct characterization of young giant exoplanets at high spectral resolution by coupling SPHERE and CRIRES+

2021 ◽  
Vol 646 ◽  
pp. A150
Author(s):  
G. P. P. L. Otten ◽  
A. Vigan ◽  
E. Muslimov ◽  
M. N’Diaye ◽  
E. Choquet ◽  
...  
Keyword(s):  
Spectral Resolution ◽  
Extrasolar Planets ◽  
Signal To Noise Ratio ◽  
Detection Limits ◽  
Spectral Lines ◽  
High Spectral Resolution ◽  
Contrast Imaging ◽  
High Contrast Imaging ◽  
The Impact

Studies of atmospheres of directly imaged extrasolar planets with high-resolution spectrographs have shown that their characterization is predominantly limited by noise on the stellar halo at the location of the studied exoplanet. An instrumental combination of high-contrast imaging and high spectral resolution that suppresses this noise and resolves the spectral lines can therefore yield higher quality spectra. We study the performance of the proposed HiRISE fiber coupling between the direct imager SPHERE and the spectrograph CRIRES+ at the Very Large Telescope for spectral characterization of directly imaged planets. Using end-to-end simulations of HiRISE we determine the signal-to-noise ratio (S/N) of the detection of molecular species for known extrasolar planets in H and K bands, and compare them to CRIRES+. We investigate the ultimate detection limits of HiRISE as a function of stellar magnitude, and we quantify the impact of different coronagraphs and of the system transmission. We find that HiRISE largely outperforms CRIRES+ for companions around bright hosts like β Pictoris or 51 Eridani. For an H = 3.5 host, we observe a gain of a factor of up to 16 in observing time with HiRISE to reach the same S/N on a companion at 200 mas. More generally, HiRISE provides better performance than CRIRES+ in 2 h integration times between 50 and 350 mas for hosts with H < 8.5 and between 50 and 700 mas for H < 7. For fainter hosts like PDS 70 and HIP 65426, no significant improvements are observed. We find that using no coronagraph yields the best S/N when characterizing known exoplanets due to higher transmission and fiber-based starlight suppression. We demonstrate that the overall transmission of the system is in fact the main driver of performance. Finally, we show that HiRISE outperforms the best detection limits of SPHERE for bright stars, opening major possibilities for the characterization of future planetary companions detected by other techniques.

scholarly journals Searching for proto-planets with MUSE

2020 ◽  
Vol 644 ◽  
pp. A149
Author(s):  
C. Xie ◽  
S. Y. Haffert ◽  
J. de Boer ◽  
M. A. Kenworthy ◽  
J. Brinchmann ◽  
...  
Keyword(s):  
Point Source ◽  
Spectral Resolution ◽  
Protoplanetary Disks ◽  
Detection Limits ◽  
Point Sources ◽  
Young Stars ◽  
High Contrast ◽  
Line Flux ◽  
Contrast Imaging ◽  
High Contrast Imaging

Context. Protoplanetary disks contain structures such as gaps, rings, and spirals, which are thought to be produced by the interaction between the disk and embedded protoplanets. However, only a few planet candidates are found orbiting within protoplanetary disks, and most of them are being challenged as having been confused with disk features. Aims. The VLT/MUSE discovery of PDS 70 c demonstrated a powerful way of searching for still-forming protoplanets by targeting accretion signatures with medium-resolution integral field spectroscopy. We aim to discover more proto-planetary candidates with MUSE, with a secondary aim of improving the high-resolution spectral differential imaging (HRSDI) technique by analyzing the instrumental residuals of MUSE. Methods. We analyzed MUSE observations of five young stars with various apparent brightnesses and spectral types. We applied the HRSDI technique to perform high-contrast imaging. The detection limits were estimated using fake planet injections. Results. With a 30 min integration time, MUSE can reach 5σ detection limits in apparent Hα line flux down to 10−14 and 10−15 erg s−1 cm−2 at 0.075′′ and 0.25′′, respectively. In addition to PDS 70 b and c, we did not detect any clear accretion signatures in PDS 70, J1850-3147, and V1094 Sco down to 0.1′′. MUSE avoids the small sample statistics problem by measuring the noise characteristics in the spatial direction at multiple wavelengths. We detected two asymmetric atomic jets in HD 163296 with a very high spatial resolution (down to 8 au) and medium spectral resolution (R ~ 2500). Conclusions. The HRSDI technique when applied to MUSE data allows us to reach the photon noise limit at small separations (i.e., <0.5′′). With the combination of high-contrast imaging and medium spectral resolution, MUSE can achieve fainter detection limits in apparent line flux than SPHERE/ZIMPOL by a factor of ~5. MUSE has some instrumental issues that limit the contrast that appear in cases with strong point sources, which can be either a spatial point source due to high Strehl observations or a spectral point source due to a high line-to-continuum ratio. We modified the HRSDI technique to better handle the instrumental artifacts and improve the detection limits. To avoid the instrumental effects altogether, we suggest faint young stars with relatively low Hα line-to-continuum ratio to be the most suitable targets for MUSE to search for potential protoplanets.

scholarly journals Characterization of a photon counting EMCCD for space-based high contrast imaging spectroscopy of extrasolar planets

2014 ◽  
Author(s):  
Ashlee N. Wilkins ◽  
Michael W. McElwain ◽  
Timothy J. Norton ◽  
Bernie J. Rauscher ◽  
Johannes F. Rothe ◽  
...  
Keyword(s):  
Extrasolar Planets ◽  
Imaging Spectroscopy ◽  
Photon Counting ◽  
High Contrast ◽  
Contrast Imaging ◽  
High Contrast Imaging

Measurement of Dysprosium Stark Width and the Electron Impact Width Parameter

2018 ◽  
Vol 73 (2) ◽  
pp. 203-213 ◽  
Author(s):  
Jhonatha R. dos Santos ◽  
Jonas Jakutis Neto ◽  
N. Rodrigues ◽  
M.G. Destro ◽  
José W. Neri ◽  
...  
Keyword(s):  
Electron Density ◽  
Impact Parameter ◽  
Plasma Temperature ◽  
Spectral Lines ◽  
Emission Lines ◽  
Spectroscopic Methods ◽  
Species Concentration ◽  
The Impact ◽  
Stark Width

In this work, we suggest a methodology to determine the impact parameter for neutral dysprosium emission lines from the characterization of the plasma generated by laser ablation in a sealed chamber filled with argon. The procedure is a combination of known consistent spectroscopic methods for plasma temperature determination, electron density, and species concentration. With an electron density of 3.1 × 1018 cm–3 and temperature close to 104 K, we estimated the impact electron parameter for nine spectral lines of the neutral dysprosium atom. The gaps in the impact parameter data in the literature, mainly for heavy elements, stress the importance of the proposed method.

scholarly journals precision: a fast python pipeline for high-contrast imaging – application to SPHERE observations of the red supergiant VX Sagitariae

2020 ◽  
Vol 494 (3) ◽  
pp. 3200-3211
Author(s):  
P Scicluna ◽  
F Kemper ◽  
R Siebenmorgen ◽  
R Wesson ◽  
J A D L Blommaert ◽  
...  
Keyword(s):  
Near Infrared ◽  
Extrasolar Planets ◽  
Asymmetric Structure ◽  
High Contrast ◽  
Contrast Imaging ◽  
Near Ir ◽  
High Contrast Imaging ◽  
Infrared Imager ◽  
Imaging Application ◽  
Efficient Reduction

ABSTRACT The search for extrasolar planets has driven rapid advances in instrumentation, resulting in cameras such as SPHERE at the VLT, GPI at Gemini South and SCExAO at Subaru, capable of achieving very high contrast (∼106) around bright stars with small inner working angles (${\sim}0.1\,{\rm arcsec}$). The optimal exploitation of data from these instruments depends on the availability of easy-to-use software to process and analyse their data products. We present a pure-python pipeline, precision, which provides fast, memory-efficient reduction of data from the SPHERE/IRDIS near-infrared imager, and can be readily extended to other instruments. We apply precision to observations of the extreme red supergiant VX Sgr, the inner outflow of which is revealed to host complex, asymmetric structure in the near-IR. In addition, optical polarimetric imaging reveals clear extended polarized emission on ∼0.5 arcsec scales that varies significantly with azimuth, confirming the asymmetry. While not conclusive, this could suggest that the ejecta are confined to a disc or torus, which we are viewing nearly face on, although other non-spherical or clumpy configurations remain possible. VX Sgr has no known companions, making such a geometry difficult to explain, as there is no obvious source of angular momentum in the system.

scholarly journals Characterization of Metabolic Differences between Benign and Malignant Tumors: High-Spectral-Resolution Diffuse Optical Spectroscopy

Radiology ◽  
2010 ◽  
Vol 254 (1) ◽  
pp. 277-284 ◽  
Author(s):  
Shwayta Kukreti ◽  
Albert E. Cerussi ◽  
Wendy Tanamai ◽  
David Hsiang ◽  
Bruce J. Tromberg ◽  
...  
Keyword(s):  
Optical Spectroscopy ◽  
Spectral Resolution ◽  
Malignant Tumors ◽  
High Spectral Resolution ◽  
Diffuse Optical Spectroscopy

scholarly journals Added-value of GEO-hyperspectral Infrared Radiances for Local Severe Storm Forecasts Using the Hybrid OSSE Method

2021 ◽  
Author(s):  
Pei Wang ◽  
Zhenglong Li ◽  
Jun Li ◽  
Timothy J. Schmit
Keyword(s):  
Spectral Resolution ◽  
Weather Prediction ◽  
Atmospheric Temperature ◽  
Added Value ◽  
High Spectral Resolution ◽  
Vertical Resolution ◽  
Severe Storm ◽  
Impact Studies ◽  
High Vertical Resolution ◽  
The Impact

AbstractHigh spectral resolution (or hyperspectral) infrared (IR) sounders onboard low earth orbiting satellites provide high vertical resolution atmospheric information for numerical weather prediction (NWP) models. In contrast, imagers on geostationary (GEO) satellites provide high temporal and spatial resolution which are important for monitoring the moisture associated with severe weather systems, such as rapidly developing local severe storms (LSS). A hyperspectral IR sounder onboard a geostationary satellite would provide four-dimensional atmospheric temperature, moisture, and wind profiles that have both high vertical resolution and high temporal/spatial resolutions. In this work, the added-value from a GEO-hyperspectral IR sounder is studied and discussed using a hybrid Observing System Simulation Experiment (OSSE) method. A hybrid OSSE is distinctively different from the traditional OSSE in that, (a) only future sensors are simulated from the nature run and (b) the forecasts can be evaluated using real observations. This avoids simulating the complicated observation characteristics of the current systems (but not the new proposed system) and allows the impact to be assessed against real observations. The Cross-track Infrared Sounder (CrIS) full spectral resolution (FSR) is assumed to be onboard a GEO for the impact studies, and the GEO CrIS radiances are simulated from the ECMWF Reanalysis v5 (ERA5) with the hyperspectral IR all-sky radiative transfer model (HIRTM). The simulated GEO CrIS radiances are validated and the hybrid OSSE system is verified before the impact assessment. Two LSS cases from 2018 and 2019 are selected to evaluate the value-added impacts from the GEO CrIS-FSR data. The impact studies show improved atmospheric temperature, moisture, and precipitation forecasts, along with some improvements in the wind forecasts. An added-value, consisting of an overall 5% Root Mean Square Error (RMSE) reduction, was found when a GEO CrIS-FSR is used in replacement of LEO ones indicating the potential for applications of data from a GEO hyperspectral IR sounder to improve local severe storm forecasts.

Spectroscopic and structural characterization of three silaisocyanides: exploring an elusive class of reactive molecules at high resolution

2015 ◽  
Vol 51 (56) ◽  
pp. 11305-11308 ◽  
Author(s):  
Sven Thorwirth ◽  
Ralf I. Kaiser ◽  
Kyle N. Crabtree ◽  
Michael C. McCarthy
Keyword(s):  
High Resolution ◽  
Spectral Resolution ◽  
Structural Characterization ◽  
High Spectral Resolution ◽  
First Time

The fundamental silaisocyanides HCCNSi, HC4NSi, and NCNSi have been characterized at high spectral resolution for the first time. All three chains are good candidates for radio astronomical detection.

Sign in / Sign up

Export Citation Format

Share Document