Search for cool extrasolar giant planets combining coronagraphy, spectral and angular differential imaging

AbstractSpectral differential imaging (SDI) is part of the observing strategy of current and on-going high-contrast imaging instruments on ground-based telescopes. Although it improves the star light rejection, SDI attenuates the signature of off-axis companions to the star, just like angular differential imaging (ADI). However, the attenuation due to SDI has the peculiarity of being dependent on the spectral properties of the companions. To date, no study has investigated these effects. Our team is addressing this problem based on data from a direct imaging survey of 16 stars combining the phase-mask coronagraph, the SDI and the ADI modes of VLT/NaCo. The objective of the survey is to search for cool (Teff<1000-1300 K) giant planets at separations of 5-10 AU orbiting young, nearby stars (<200 Myr, <25 pc). The data analysis did not yield any detections. As for the estimation of the sensivity limits of SDI-processed images, we show that it requires a different analysis than that used in ADI-based surveys. Based on a method using the flux predictions of evolutionary models and avoiding the estimation of contrast, we determine directly the mass sensivity limits of the survey for the ADI processing alone and with the combination of SDI and ADI. We show that SDI does not systematically improve the sensitivity due to the spectral properties and self-subtraction of point sources.

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In-lab testing of six-level phase mask coronagraphs onto the high-contrast imaging THD2 bench

Adaptive Optics Systems VI ◽

10.1117/12.2314152 ◽

2018 ◽

Author(s):

Fabien Patru ◽

Pierre Baudoz ◽

Raphaël Galicher ◽

Qing Cao ◽

Kai Wang ◽

...

Keyword(s):

Phase Mask ◽

High Contrast ◽

Contrast Imaging ◽

High Contrast Imaging

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High-contrast Imaging with a Small, Well-corrected Subaperture and a Phase-mask Coronagraph

10.1063/1.3215878 ◽

2009 ◽

Author(s):

D. Mawet ◽

E. Serabyn ◽

Tomonori Usuda ◽

Motohide Tamura ◽

Miki Ishii

Keyword(s):

Phase Mask ◽

High Contrast ◽

Contrast Imaging ◽

High Contrast Imaging

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Searching for proto-planets with MUSE

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038242 ◽

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.

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VLT/SPHERE Multiwavelength High-contrast Imaging of the HD 115600 Debris Disk: New Constraints on the Dust Geometry and the Presence of Young Giant Planets

The Astronomical Journal ◽

10.3847/1538-3881/aaf1bd ◽

2019 ◽

Vol 157 (1) ◽

pp. 39 ◽

Cited By ~ 5

Author(s):

Aidan Gibbs ◽

Kevin Wagner ◽

Daniel Apai ◽

Attila Moór ◽

Thayne Currie ◽

...

Keyword(s):

Giant Planets ◽

High Contrast ◽

Contrast Imaging ◽

High Contrast Imaging ◽

Debris Disk

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Laboratory validation of the dual-zone phase mask coronagraph in broadband light at the high-contrast imaging THD testbed

Astronomy and Astrophysics ◽

10.1051/0004-6361/201628587 ◽

2016 ◽

Vol 592 ◽

pp. A119 ◽

Cited By ~ 14

Author(s):

J. R. Delorme ◽

M. N’Diaye ◽

R. Galicher ◽

K. Dohlen ◽

P. Baudoz ◽

...

Keyword(s):

Phase Mask ◽

High Contrast ◽

Contrast Imaging ◽

High Contrast Imaging

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Medium-resolution integral-field spectroscopy for high-contrast exoplanet imaging

Astronomy and Astrophysics ◽

10.1051/0004-6361/201832902 ◽

2018 ◽

Vol 617 ◽

pp. A144 ◽

Cited By ~ 20

Author(s):

H. J. Hoeijmakers ◽

H. Schwarz ◽

I. A. G. Snellen ◽

R. J. de Kok ◽

M. Bonnefoy ◽

...

Keyword(s):

Adaptive Optics ◽

Cross Correlation ◽

High Contrast ◽

Contrast Imaging ◽

Data Set ◽

Stellar Spectrum ◽

High Contrast Imaging ◽

Medium Resolution ◽

Differential Imaging ◽

Integral Field

Context. Angular differential imaging (ADI) and spectral differential imaging (SDI) are well-established high-contrast imaging techniques, but their application is challenging for companions at small angular separations from their host stars. Aims. The aim of this paper is to investigate to what extent adaptive-optics assisted, medium-resolution (R ~ 5000) integral field spectrographs (IFS) can be used to directly detect the absorption of molecular species in the spectra of planets and substellar companions when these are not present in the spectrum of the star. Methods. We analysed archival data of the β Pictoris system taken with the SINFONI integral field spectrograph located at ESO’s Very Large Telescope, originally taken to image β Pictoris b using ADI techniques. At each spatial position in the field, a scaled instance of the stellar spectrum is subtracted from the data after which the residuals are cross-correlated with model spectra. The cross-correlation co-adds the individual absorption lines of the planet emission spectrum constructively, while this is not the case for (residual) telluric and stellar features. Results. Cross-correlation with CO and H2O models results in significant detections of β Pictoris b with signal-to-noise ratios (S/Ns) of 13.7 and 16.4 respectively. Correlation with a T = 1700 K BT-Settl model provides a detection with an S/N of 22.8. This in contrast to application of ADI, which barely reveals the planet. While the adaptive optics system only achieved modest Strehl ratios of 19–27% leading to a raw contrast of 1:240 at the planet position, cross-correlation achieves a 3σ contrast limit of 2.7 × 10−5 in this 2.5 hr data set, a factor ~40 below the raw noise level at an angular distance of 0.36′′ from the star. Conclusions. Adaptive-optics assisted, medium-resolution IFS, such as SINFONI on the VLT and OSIRIS on the Keck Telescope, can be used for high-contrast imaging utilizing cross-correlation techniques for planets that are close to their star and embedded in speckle noise. We refer to this method as molecule mapping, and advocate its application to observations with future medium resolution instruments, in particular ERIS on the VLT, HARMONI on the ELT and NIRSpec, and MIRI on the JWST.

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A UNIFORM ANALYSIS OF 118 STARS WITH HIGH-CONTRAST IMAGING: LONG-PERIOD EXTRASOLAR GIANT PLANETS ARE RARE AROUND SUN-LIKE STARS

The Astrophysical Journal ◽

10.1088/0004-637x/717/2/878 ◽

2010 ◽

Vol 717 (2) ◽

pp. 878-896 ◽

Cited By ~ 92

Author(s):

Eric L. Nielsen ◽

Laird M. Close

Keyword(s):

Giant Planets ◽

High Contrast ◽

Contrast Imaging ◽

Long Period ◽

High Contrast Imaging

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The Gemini NICI Planet-Finding Campaign: The Frequency of Giant Planets around Young B and A Stars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313007874 ◽

2013 ◽

Vol 8 (S299) ◽

pp. 60-61

Author(s):

Eric L. Nielsen ◽

Michael C. Liu ◽

Zahed Wahhaj ◽

Beth A. Biller ◽

Thomas L. Hayward ◽

...

Keyword(s):

Brown Dwarfs ◽

Giant Planets ◽

High Mass ◽

High Contrast ◽

Brown Dwarf ◽

Contrast Imaging ◽

High Contrast Imaging ◽

Null Result ◽

Upper Limits

AbstractWe have carried out high contrast imaging of 70 young, nearby B and A stars to search for brown dwarf and planetary companions as part of the Gemini NICI Planet-Finding Campaign. Our survey represents the largest, deepest survey for planets around high-mass stars (≈1.5–2.5 M⊙) conducted to date and includes the planet hosts β Pic and Fomalhaut. Despite detecting two new brown dwarfs, our observations did not detect new planets around our target stars, and we present upper limits on the fraction of high-mass stars that can host giant planets that are consistent with our null result.

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