scholarly journals Adaptive Optics Observations of Exoplanets, Brown Dwarfs, and Binary Stars

2011 ◽  
Vol 7 (S282) ◽  
pp. 181-188
Author(s):  
Sasha Hinkley
Keyword(s):  
Adaptive Optics ◽  
Binary Stars ◽  
Imaging Techniques ◽  
Contrast Ratio ◽  
Brown Dwarfs ◽  
Formation Mechanisms ◽  
High Contrast ◽  
Contrast Imaging ◽  
High Contrast Imaging ◽  
Low Mass

AbstractThe current direct observations of brown dwarfs and exoplanets have been obtained using instruments not specifically designed for overcoming the large contrast ratio between the host star and any wide-separation faint companions. However, we are about to witness the birth of several new dedicated observing platforms specifically geared towards high contrast imaging of these objects. The Gemini Planet Imager, VLT-SPHERE, Subaru HiCIAO, and Project 1640 at the Palomar 5m telescope will return images of numerous exoplanets and brown dwarfs over hundreds of observing nights in the next five years. Along with diffraction-limited coronagraphs and high-order adaptive optics, these instruments also will return spectral and polarimetric information on any discovered targets, giving clues to their atmospheric compositions and characteristics. Such spectral characterization will be key to forming a detailed theory of comparative exoplanetary science which will be widely applicable to both exoplanets and brown dwarfs. Further, the prevalence of aperture masking interferometry in the field of high contrast imaging is also allowing observers to sense massive, young planets at solar system scales (~3–30 AU)— separations out of reach to conventional direct imaging techniques. Such observations can provide snapshots at the earliest phases of planet formation—information essential for constraining formation mechanisms as well as evolutionary models of planetary mass companions. As a demonstration of the power of this technique, I briefly review recent aperture masking observations of the HR 8799 system. Moreover, all of the aforementioned techniques are already extremely adept at detecting low-mass stellar companions to their target stars, and I present some recent highlights.

scholarly journals SPOTS: The Search for Planets Orbiting Two Stars

2018 ◽  
Vol 619 ◽  
pp. A43 ◽  
Author(s):  
R. Asensio-Torres ◽  
M. Janson ◽  
M. Bonavita ◽  
S. Desidera ◽  
C. Thalmann ◽  
...  
Keyword(s):  
Binary Stars ◽  
Imaging Techniques ◽  
Contrast Imaging ◽  
Direct Imaging ◽  
Upper Limit ◽  
High Contrast Imaging ◽  
Survey Results ◽  
Low Mass ◽  
Best Fit ◽  
Observational Program

Binary stars constitute a large percentage of the stellar population, yet relatively little is known about the planetary systems orbiting them. Most constraints on circumbinary planets (CBPs) so far come from transit observations with the Kepler telescope, which is sensitive to close-in exoplanets but does not constrain planets on wider orbits. However, with continuous developments in high-contrast imaging techniques, this population can now be addressed through direct imaging. We present the full survey results of the Search for Planets Orbiting Two Stars (SPOTS) survey, which is the first direct imaging survey targeting CBPs. The SPOTS observational program comprises 62 tight binaries that are young and nearby, and thus suitable for direct imaging studies, with VLT/NaCo and VLT/SPHERE. Results from SPOTS include the resolved circumbinary disk around AK Sco, the discovery of a low-mass stellar companion in a triple packed system, the relative astrometry of up to 9 resolved binaries, and possible indications of non-background planetary-mass candidates around HIP 77911. We did not find any CBP within 300 AU, which implies a frequency upper limit on CBPs (1–15 MJup) of 6–10% between 30–300 AU. Coupling these observations with an archival dataset for a total of 163 stellar pairs, we find a best-fit CBP frequency of 1.9% (2–15 MJup) between 1 and 300 AU with a 10.5% upper limit at a 95% confidence level. This result is consistent with the distribution of companions around single stars.

scholarly journals Direct imaging and spectroscopy of exoplanets with the ELT/HARMONI high-contrast module

2021 ◽  
Author(s):  
Mathis Houllé ◽  
Arthur Vigan ◽  
Alexis Carlotti ◽  
Élodie Choquet ◽  
Faustine Cantalloube ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Near Infrared ◽  
Direct Detection ◽  
Imaging Techniques ◽  
High Contrast ◽  
Contrast Imaging ◽  
High Contrast Imaging ◽  
Medium Resolution ◽  
Imaging And Spectroscopy ◽  
Integral Field Spectrograph

<p>Combining high-contrast imaging with medium-resolution spectroscopy has recently been shown to significantly boost the direct detection of exoplanets. In this optic, HARMONI, one of the first-light instruments to be mounted on ESO's ELT, will be equipped with a single-conjugated adaptive optics system to reach the diffraction limit of the ELT in H and K bands, a high-contrast module dedicated to exoplanet imaging, and a medium-resolution (up to R = 17 000) optical and near-infrared integral field spectrograph. When combined, these systems will provide unprecedented contrast limits at separations between 50 and 400 mas. We will present in this talk the results of extensive simulations of exoplanet observations with the HARMONI high-contrast module. We used an end-to-end model of the instrument to simulate observations based on realistic observing scenarios and conditions. We then analyzed these observations with the so-called "molecule mapping" technique, which has shown in recent studies its efficiency to disentangle planetary companions from their host star and boost their signal. Although HARMONI has not been fully designed for high-contrast imaging, we will show that it should greatly outperform the current dedicated instruments, such as SPHERE on the VLT. We detect planets above 5σ in 2 hours at contrasts up to 16 mag and separations down to 75 mas in several spectral configurations of the instrument. Simulating planets from population synthesis models, we could image in this amount of time companions as close as 1 AU from a host star at 30 pc and as light as 2 M<sub>Jup</sub>. We show that taking advantage of the combination of high-contrast imaging and medium-resolution spectroscopy through molecule mapping allows us to access much fainter planets (up to 2.5 mag) than the standard high-contrast imaging techniques. We also demonstrate that HARMONI should be available for near-critical exoplanet observations with this method during 60 to 70% of telescope time at the ELT.</p>

Enabling high-contrast imaging of binary stars with the Roman Space Telescope Coronagraph Instrument

2021 ◽  
Author(s):  
Eduardo Bendek ◽  
Ruslan Belikov ◽  
Dan Sirbu ◽  
Garreth Ruane ◽  
A. J. Eldorado Riggs ◽  
...  
Keyword(s):  
Binary Stars ◽  
High Contrast ◽  
Contrast Imaging ◽  
Space Telescope ◽  
High Contrast Imaging

scholarly journals High-fidelity photometry and astrometry of high-contrast imaged companions using LOCI processing.

2013 ◽  
Vol 8 (S299) ◽  
pp. 44-45
Author(s):  
Jérôme Maire ◽  
Jonathan Gagné ◽  
David Lafrenière ◽  
James R. Graham ◽  
René Doyon
Keyword(s):  
Contrast Ratio ◽  
Angular Separation ◽  
Speckle Noise ◽  
High Contrast ◽  
Contrast Imaging ◽  
High Contrast Imaging ◽  
Suppression Technique ◽  
Imaging And Spectroscopy ◽  
And Migration ◽  
Imaging Performance

RésuméDirect imaging and spectroscopy of exoplanets is a key element for understanding planet formation and migration. Such direct detections and characterizations remains technologically challenging, since a very high contrast ratio and small angular separation are involved, and futhermore speckle noise limits the high-contrast imaging performance. We further discuss a speckle subtraction and suppression technique that fully takes advantage of spectral and time-domain information on quasi-static speckles to measure the highest-fidelity photometry as well as accurate astrometry of detected companions.

High Contrast Imaging for Python (HCIPy): an open-source adaptive optics and coronagraph simulator

2018 ◽  
Author(s):  
Emiel H. Por ◽  
Sebastiaan Y. Haffert ◽  
Vikram Mark Radhakrishnan ◽  
David S. Doelman ◽  
Maaike van Kooten ◽  
...  
Keyword(s):  
Open Source ◽  
Adaptive Optics ◽  
High Contrast ◽  
Contrast Imaging ◽  
High Contrast Imaging

scholarly journals Carina High-contrast Imaging Project for massive Stars (CHIPS)

2020 ◽  
Vol 640 ◽  
pp. A15
Author(s):  
A. Rainot ◽  
M. Reggiani ◽  
H. Sana ◽  
J. Bodensteiner ◽  
C. A. Gomez-Gonzalez ◽  
...  
Keyword(s):  
Main Sequence ◽  
Massive Stars ◽  
Imaging Techniques ◽  
Mass Function ◽  
Local Source ◽  
High Contrast ◽  
Contrast Imaging ◽  
Solar Mass ◽  
Low Mass ◽  
Spectral Channels

Context. Massive stars like company. However, low-mass companions have remained extremely difficult to detect at angular separations (ρ) smaller than 1″ (approx. 1000–3000 au, considering the typical distance to nearby massive stars) given the large brightness contrast between the companion and the central star. Constraints on the low-mass end of the companions mass-function for massive stars are needed, however, for helping, for example, to distinguish among the various scenarios that describe the formation of massive stars. Aims. With the aim of obtaining a statistically significant constraint on the presence of low-mass companions beyond the typical detection limit of current surveys (Δmag ≲ 5 at ρ ≲ 1″), we initiated a survey of O and Wolf-Rayet stars in the Carina region using the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) coronagraphic instrument on the Very Large Telescope (VLT). In this, the first paper of the series, we aim to introduce the survey, to present the methodology and to demonstrate the capability of SPHERE for massive stars using the multiple system QZ Car. Methods. We obtained VLT-SPHERE snapshot observations in the IRDIFS_EXT mode, which combines the IFS and IRDIS sub-systems and simultaneously provides us four-dimensional (4D) data cubes in two different fields-of-view: 1.73″ × 1.73″ for IFS (39 spectral channels across the YJH bands) and 12″ × 12″ for IRDIS (two spectral channels across the K band). Angular- and spectral-differential imaging techniques as well as PSF-fitting were applied to detect and measure the relative flux of the companions in each spectral channel. The latter were then flux-calibrated using theoretical SED models of the central object and compared to a grid of ATLAS9 atmosphere model and (pre-)main-sequence evolutionary tracks, providing a first estimate of the physical properties of the detected companions. Results. Detection limits of 9 mag at ρ >  200 mas for IFS, and as faint as 13 mag at ρ > 1.​″8 for IRDIS (corresponding to sub-solar masses for potential companions), can be reached in snapshot observations of only a few minutes integration times, allowing us to detect 19 sources around the QZ Car system. All but two are reported here for the first time. With near-IR magnitude contrasts in the range of 4 to 7.5 mag, the three brightest sources (Ab, Ad, and E) are most likely to be physically bound. They have masses in the range of 2 to 12 M⊙ and are potentially co-eval with QZ Car central system. The remaining sources have flux contrast of 1.5 × 105 to 9.5 × 106 (ΔK ≈ 11 to 13 mag). Their presence can be explained by the local source density and they are, thus, likely to be chance alignments. If they were members of the Carina nebula, they would be sub-solar-mass pre-main sequence stars. Conclusions. Based on this proof of concept, we show that the VLT/SPHERE allows us to reach the sub-solar mass regime of the companion mass function. It paves the way for this type of observation with a large sample of massive stars to provide novel constraints on the multiplicity of massive stars in a region of the parameter space that has remained inaccessible so far.

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