scholarly journals ISPY – NaCo Imaging Survey for Planets around Young stars

2019 ◽  
Vol 624 ◽  
pp. A29 ◽  
Author(s):  
G. Cugno ◽  
S. P. Quanz ◽  
R. Launhardt ◽  
A. Musso Barcucci ◽  
S. S. Brems ◽  
...  
Keyword(s):  
Circular Orbit ◽  
Position Angle ◽  
Young Stars ◽  
Imaging Data ◽  
Contrast Imaging ◽  
High Contrast Imaging ◽  
Very Large Telescope ◽  
Low Mass ◽  
Background Object ◽  
One Year

Context. Within the NaCo-ISPY exoplanet imaging program, we aim at detecting and characterizing the population of low-mass companions at wide separations (≳10 AU), focusing in particular on young stars either hosting a known protoplanetary disk or a debris disk. Aims. R CrA is one of the youngest (1–3 Myr) and most promising objects in our sample because of two previous studies that suggested the presence of a close companion. Our aim is to directly image and characterize the companion for the first time. Methods. We observed R CrA twice with the NaCo instrument at the Very Large Telescope (VLT) in the L′ filter with a one year time baseline in between. The high-contrast imaging data were reduced and analyzed and the companion candidate was detected in both datasets. We used artificial negative signals to determine the position and brightness of the companion and the related uncertainties. Results. The companion is detected at a separation of 196.8 ± 4.5/196.6 ± 5.9 mas (18.7 ± 1.3/18.7 ± 1.4 AU) and position angle of 134.7 ± 0.5 ° /133.7 ± 0.7° in the first/second epoch observation. We measure a contrast of 7.29 ± 0.18/6.70 ± 0.15 mag with respect to the primary. A study of the stellar proper motion rejects the hypothesis that the signal is a background object. The companion candidate orbits in the clockwise direction and, if on a face-on circular orbit, its period is ∼43 − 47 yr. This value disagrees with the estimated orbital motion and therefore a face-on circular orbit may be excluded. Depending on the assumed age, extinction, and brightness of the primary, the stellar companion has a mass between 0.10 ± 0.02 M⊙ and 1.03−0.18+0.20 M⊙ range, if no contribution from circumsecondary material is taken into account. Conclusions. As already hypothesized by previous studies, we directly detected a low-mass stellar companion orbiting the young Herbig Ae/Be star R CrA. Depending on the age assumptions, the companion is among the youngest forming companions imaged to date, and its presence needs to be taken into account when analyzing the complex circumstellar environment of R CrA.

scholarly journals PynPoint: a modular pipeline architecture for processing and analysis of high-contrast imaging data

2019 ◽  
Vol 621 ◽  
pp. A59 ◽  
Author(s):  
T. Stolker ◽  
M. J. Bonse ◽  
S. P. Quanz ◽  
A. Amara ◽  
G. Cugno ◽  
...  
Keyword(s):  
Data Reduction ◽  
Direct Detection ◽  
Principal Component ◽  
Monte Carlo Analysis ◽  
Data Sets ◽  
High Contrast ◽  
Imaging Data ◽  
Pipeline Architecture ◽  
Contrast Imaging ◽  
High Contrast Imaging

Context. The direct detection and characterization of planetary and substellar companions at small angular separations is a rapidly advancing field. Dedicated high-contrast imaging instruments deliver unprecedented sensitivity, enabling detailed insights into the atmospheres of young low-mass companions. In addition, improvements in data reduction and point spread function (PSF)-subtraction algorithms are equally relevant for maximizing the scientific yield, both from new and archival data sets. Aims. We aim at developing a generic and modular data-reduction pipeline for processing and analysis of high-contrast imaging data obtained with pupil-stabilized observations. The package should be scalable and robust for future implementations and particularly suitable for the 3–5 μm wavelength range where typically thousands of frames have to be processed and an accurate subtraction of the thermal background emission is critical. Methods. PynPoint is written in Python 2.7 and applies various image-processing techniques, as well as statistical tools for analyzing the data, building on open-source Python packages. The current version of PynPoint has evolved from an earlier version that was developed as a PSF-subtraction tool based on principal component analysis (PCA). Results. The architecture of PynPoint has been redesigned with the core functionalities decoupled from the pipeline modules. Modules have been implemented for dedicated processing and analysis steps, including background subtraction, frame registration, PSF subtraction, photometric and astrometric measurements, and estimation of detection limits. The pipeline package enables end-to-end data reduction of pupil-stabilized data and supports classical dithering and coronagraphic data sets. As an example, we processed archival VLT/NACO L′ and M′ data of β Pic b and reassessed the brightness and position of the planet with a Markov chain Monte Carlo analysis; we also provide a derivation of the photometric error budget.

scholarly journals Constraining the properties of HD 206893 B

2019 ◽  
Vol 627 ◽  
pp. L9 ◽  
Author(s):  
A. Grandjean ◽  
A.-M. Lagrange ◽  
H. Beust ◽  
L. Rodet ◽  
J. Milli ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Semimajor Axis ◽  
High Contrast ◽  
Brown Dwarf ◽  
Contrast Imaging ◽  
Dynamical Mass ◽  
Orbital Parameters ◽  
High Contrast Imaging ◽  
Very Large Telescope ◽  
Astrometric Data

Context. High contrast imaging enables the determination of orbital parameters for substellar companions (planets, brown dwarfs) from the observed relative astrometry and the estimation of model and age-dependent masses from their observed magnitudes or spectra. Combining astrometric positions with radial velocity gives direct constraints on the orbit and on the dynamical masses of companions. A brown dwarf was discovered with the VLT/SPHERE instrument at the Very Large Telescope (VLT) in 2017, which orbits at ∼11 au around HD 206893. Its mass was estimated between 12 and 50 MJ from evolutionary models and its photometry. However, given the significant uncertainty on the age of the system and the peculiar spectrophotometric properties of the companion, this mass is not well constrained. Aims. We aim at constraining the orbit and dynamical mass of HD 206893 B. Methods. We combined radial velocity data obtained with HARPS spectra and astrometric data obtained with the high contrast imaging VLT/SPHERE and VLT/NaCo instruments, with a time baseline less than three years. We then combined those data with astrometry data obtained by HIPPARCOS and Gaia with a time baseline of 24 yr. We used a Markov chain Monte Carlo approach to estimate the orbital parameters and dynamical mass of the brown dwarf from those data. Results. We infer a period between 21 and 33 yr and an inclination in the range 20−41° from pole-on from HD 206893 B relative astrometry. The RV data show a significant RV drift over 1.6 yr. We show that HD 206893 B cannot be the source of this observed RV drift as it would lead to a dynamical mass inconsistent with its photometry and spectra and with HIPPARCOS and Gaia data. An additional inner (semimajor axis in the range 1.4–2.6 au) and massive (∼15 MJ) companion is needed to explain the RV drift, which is compatible with the available astrometric data of the star, as well as with the VLT/SPHERE and VLT/NaCo nondetection.

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.

Multiplicity study of T Tauri starsin the Lupus star forming region

2018 ◽  
Vol 14 (S345) ◽  
pp. 318-319
Author(s):  
M. Mugrauer ◽  
C. Ginski ◽  
N. Vogt ◽  
R. Neuhäuser
Keyword(s):  
Main Sequence ◽  
Average Distance ◽  
High Contrast ◽  
Imaging Data ◽  
Main Sequence Stars ◽  
Contrast Imaging ◽  
Star Forming ◽  
High Contrast Imaging ◽  
T Tauri ◽  
Triple Star

AbstractWe carried out a high contrast imaging search for (sub)stellar companions of young pre-main sequence stars in the Lupus star forming region. For this project we utilized NACO/ESO-VLT, operated at the Paranal observatory. On this poster, we presented the results of this survey. In several observing campaigns we could obtain diffraction limited deep IR imaging data and detected faint co-moving companions around our targets, whose astro- and photometry was determined in all observing epochs. The co-moving companions found in our survey exhibit angular separations in the range between about 0.1 and a few arcsecs, i.e. projected separations between about 10 and a few hundreds of au, at the average distance of our targets of about 140 pc. Beside several new binary and triple star systems, whose multiplicity was revealed in this survey, also faint co-moving companions in the substellar mass regime could be identified close to some of our targets.

scholarly journals The SOPHIE search for northern extrasolar planets

2019 ◽  
Vol 625 ◽  
pp. A17 ◽  
Author(s):  
R. F. Díaz ◽  
X. Delfosse ◽  
M. J. Hobson ◽  
I. Boisse ◽  
N. Astudillo-Defru ◽  
...  
Keyword(s):  
Extrasolar Planets ◽  
Equilibrium Temperature ◽  
Current Data ◽  
Velocity Variation ◽  
High Dispersion ◽  
Correlated Noise ◽  
Contrast Imaging ◽  
High Contrast Imaging ◽  
Independent Analysis ◽  
Low Mass

Periodic radial velocity variations in the nearby M-dwarf star Gl 411 are reported, based on measurements with the SOPHIE spectrograph. Current data do not allow us to distinguish between a 12.95-day period and its one-day alias at 1.08 days, but favour the former slightly. The velocity variation has an amplitude of 1.6 m s−1, making this the lowest-amplitude signal detected with SOPHIE up to now. We have performed a detailed analysis of the significance of the signal and its origin, including extensive simulations with both uncorrelated and correlated noise, representing the signal induced by stellar activity. The signal is significantly detected, and the results from all tests point to its planetary origin. Additionally, the presence of an additional acceleration in the velocity time series is suggested by the current data. On the other hand, a previously reported signal with a period of 9.9 days, detected in HIRES velocities of this star, is not recovered in the SOPHIE data. An independent analysis of the HIRES dataset also fails to unveil the 9.9-day signal. If the 12.95-day period is the real one, the amplitude of the signal detected with SOPHIE implies the presence of a planet, called Gl 411 b, with a minimum mass of around three Earth masses, orbiting its star at a distance of 0.079 AU. The planet receives about 3.5 times the insolation received by Earth, which implies an equilibrium temperature between 256 and 350 K, and makes it too hot to be in the habitable zone. At a distance of only 2.5 pc, Gl 411 b, is the third closest low-mass planet detected to date. Its proximity to Earth will permit probing its atmosphere with a combination of high-contrast imaging and high-dispersion spectroscopy in the next decade.

scholarly journals A temperate exo-Earth around a quiet M dwarf at 3.4 parsec

2018 ◽  
Vol 613 ◽  
pp. A25 ◽  
Author(s):  
X. Bonfils ◽  
N. Astudillo-Defru ◽  
R. Díaz ◽  
J.-M. Almenara ◽  
T. Forveille ◽  
...  
Keyword(s):  
Giant Planet ◽  
Angular Separation ◽  
Magnetic Activity ◽  
High Dispersion ◽  
Contrast Imaging ◽  
M Dwarfs ◽  
High Contrast Imaging ◽  
Habitable Zones ◽  
Low Mass ◽  
Large Telescopes

The combination of high-contrast imaging and high-dispersion spectroscopy, which has successfully been use to detect the atmosphere of a giant planet, is one of the most promising potential probes of the atmosphere of Earth-size worlds. The forthcoming generation of extremely large telescopes (ELTs) may obtain sufficient contrast with this technique to detect O2 in the atmosphere of those worlds that orbit low-mass M dwarfs. This is strong motivation to carry out a census of planets around cool stars for which habitable zones can be resolved by ELTs, i.e. for M dwarfs within ~5 parsec. Our HARPS survey has been a major contributor to that sample of nearby planets. Here we report on our radial velocity observations of Ross 128 (Proxima Virginis, GJ447, HIP 57548), an M4 dwarf just 3.4 parsec away from our Sun. This source hosts an exo-Earth with a projected mass m sini = 1.35 M⊕ and an orbital period of 9.9 days. Ross 128 b receives less than 1.5 times as much flux as Earth from the Sun and its equilibrium ranges in temperature between 269 K for an Earth-like albedo and 213 K for a Venus-like albedo. Recent studies place it close to the inner edge of the conventional habitable zone. An 80-day long light curve from K2 campaign C01 demonstrates that Ross 128 b does not transit. Together with the All Sky Automated Survey (ASAS) photometry and spectroscopic activity indices, the K2 photometry shows that Ross 128 rotates slowly and has weak magnetic activity. In a habitability context, this makes survival of its atmosphere against erosion more likely. Ross 128 b is the second closest known exo-Earth, after Proxima Centauri b (1.3 parsec), and the closest temperate planet known around a quiet star. The 15 mas planet-star angular separation at maximum elongation will be resolved by ELTs (>3λ∕D) in the optical bands of O2.

scholarly journals HST/STIS imaging of Fomalhaut: New main belt structure and confirmation of Fomalhaut b's eccentric orbit

2013 ◽  
Vol 8 (S299) ◽  
pp. 204-207 ◽  
Author(s):  
P. Kalas ◽  
J. R. Graham ◽  
M. P. Fitzgerald ◽  
M. Clampin
Keyword(s):  
Hubble Space Telescope ◽  
Main Belt ◽  
Contrast Imaging ◽  
Nearby Star ◽  
High Contrast Imaging ◽  
Reflected Light ◽  
New Findings ◽  
Low Mass ◽  
Dust Ring ◽  
Made In

AbstractHigh contrast imaging observations with the Hubble Space Telescope show that the nearby star Fomalhaut is surrounded by a dusty debris belt and a candidate planet, Fomalhaut b, located just inside the edge of the belt. Fomalhaut b has unexpected characteristics, such as a relatively blue spectrum, leading to the hypothesis that the detected object is a low-mass planet hosting a giant planetary dust ring or cloud seen in reflected light. Here we present new HST/STIS observations made in 2010 and 2012 that authenticate the existence of Fomalhaut b. Our MCMC analysis of four epochs of astrometry spread over eight years indicate that the orbit has a~170 AU and e~0.85. Fomalhaut b's orbit is apsidally aligned with the main belt, and periapse is located approximately ~30 AU south of the star. We also show the existence of a ~50 AU wide azimuthal dust depletion in the dust belt. These new findings provide a revised picture of Fomalhaut as a dynamically complex system, where the orbit of Fomalhaut b and the belt structure signify the presence of additional massive planets orbiting the star.

scholarly journals Unveiling the β Pictoris system, coupling high contrast imaging, interferometric, and radial velocity data

2020 ◽  
Vol 642 ◽  
pp. A18
Author(s):  
A. M. Lagrange ◽  
P. Rubini ◽  
M. Nowak ◽  
S. Lacour ◽  
A. Grandjean ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Gravity Data ◽  
Giant Planet ◽  
Base Line ◽  
High Contrast ◽  
Imaging Data ◽  
Contrast Imaging ◽  
Orbital Parameters ◽  
High Contrast Imaging ◽  
The Impact

Context. The nearby and young β Pictoris system hosts a well resolved disk, a directly imaged massive giant planet orbiting at ≃9 au, as well as an inner planet orbiting at ≃2.7 au, which was recently detected through radial velocity (RV). As such, it offers several unique opportunities for detailed studies of planetary system formation and early evolution. Aims. We aim to further constrain the orbital and physical properties of β Pictoris b and c using a combination of high contrast imaging, long base-line interferometry, and RV data. We also predict the closest approaches or the transit times of both planets, and we constrain the presence of additional planets in the system. Methods. We obtained six additional epochs of SPHERE data, six additional epochs of GRAVITY data, and five additional epochs of RV data. We combined these various types of data in a single Markov-chain Monte Carlo analysis to constrain the orbital parameters and masses of the two planets simultaneously. The analysis takes into account the gravitational influence of both planets on the star and hence their relative astrometry. Secondly, we used the RV and high contrast imaging data to derive the probabilities of presence of additional planets throughout the disk, and we tested the impact of absolute astrometry. Results. The orbital properties of both planets are constrained with a semi-major axis of 9.8 ± 0.4 au and 2.7 ± 0.02 au for b and c, respectively, and eccentricities of 0.09 ± 0.1 and 0.27 ± 0.07, assuming the HIPPARCOS distance. We note that despite these low fitting error bars, the eccentricity of β Pictoris c might still be over-estimated. If no prior is provided on the mass of β Pictoris b, we obtain a very low value that is inconsistent with what is derived from brightness-mass models. When we set an evolutionary model motivated prior to the mass of β Pictoris b, we find a solution in the 10–11 MJup range. Conversely, β Pictoris c’s mass is well constrained, at 7.8 ± 0.4 MJup, assuming both planets are on coplanar orbits. These values depend on the assumptions on the distance of the β Pictoris system. The absolute astrometry HIPPARCOS-Gaia data are consistent with the solutions presented here at the 2σ level, but these solutions are fully driven by the relative astrometry plus RV data. Finally, we derive unprecedented limits on the presence of additional planets in the disk. We can now exclude the presence of planets that are more massive than about 2.5 MJup closer than 3 au, and more massive than 3.5 MJup between 3 and 7.5 au. Beyond 7.5 au, we exclude the presence of planets that are more massive than 1–2 MJup. Conclusions. Combining relative astrometry and RVs allows one to precisely constrain the orbital parameters of both planets and to give lower limits to potential additional planets throughout the disk. The mass of β Pictoris c is also well constrained, while additional RV data with appropriate observing strategies are required to properly constrain the mass of β Pictoris b.

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.

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