TRIDENT: an infrared camera optimized for the detection of methanated substellar companions of nearby stars

We present results of the first large (> 100 stars) infrared coronographic search for substellar companions to nearby stars. The search consisted of two surveys of stars chosen for their youth and proximity to Earth: 1.) a 178 star infrared survey at Steward and Lick Observatories, with optical followup from Keck Observatory, capable of detecting companions with masses greater than 30MJ, orbiting between about 75 and 300 AU, 2.) a 102 star survey using the Keck telescope, capable of detecting extrasolar brown dwarfs and planets typically more massive than 10 MJ, orbiting between about 75 and 300 AU.This research resulted in the discovery of one brown dwarf companion, zero planets and 23 double stars. The frequency of brown dwarf companions (of any mass) to G, K and M stars orbiting between 75 and 300 AU is measured to be 1 ± 1 %. The frequency of massive (> 30 MJ) brown dwarf companions is found to be 0.6 ± 0.6 %. The frequency of giant planets with masses larger than 10 MJ, between 75 and 300 AU, is measured here for the first time to be no more than about 3 %.

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Differential Simultaneous Imaging and Faint Companions: TRIDENT First Results from CFHT

Symposium - International Astronomical Union ◽

10.1017/s0074180900210735 ◽

2003 ◽

Vol 211 ◽

pp. 275-278 ◽

Cited By ~ 2

Author(s):

Christian Marois ◽

Daniel Nadeau ◽

René Doyon ◽

René Racine ◽

Gordon A. H. Walker

Keyword(s):

Infrared Camera ◽

Primary Star ◽

Methane Absorption ◽

Simultaneous Imaging ◽

First Results ◽

Nearby Stars ◽

Differential Imaging

We present the first results obtained at CFHT with the TRIDENT infrared camera, dedicated to the detection of faint companions close to bright nearby stars. Its main feature is the acquisition of three simultaneous images in three wavelengths (simultaneous differential imaging) across the methane absorption bandhead at 1.6μm, that enables a precise subtraction of the primary star PSF while keeping the companion signal. Thirty-five stars have been observed in two observing missions, with no detection so far. It is shown that a faint companion with a ΔH of 10 magnitudes would be detected at 0.5″ from the primary.

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Stellar and substellar companions of nearby stars from Gaia DR2

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834371 ◽

2019 ◽

Vol 623 ◽

pp. A72 ◽

Cited By ~ 52

Author(s):

Pierre Kervella ◽

Frédéric Arenou ◽

François Mignard ◽

Frédéric Thévenin

Keyword(s):

Proper Motion ◽

Motion Vector ◽

Tangential Velocity ◽

Long Period ◽

Nearby Stars ◽

Low Mass ◽

Substellar Companions ◽

Orbital Periods ◽

The Masses

Context. The census of stellar and substellar companions of nearby stars is largely incomplete, in particular toward the low-mass brown dwarf and long-period exoplanets. It is, however, fundamentally important in the understanding of the stellar and planetary formation and evolution mechanisms. Nearby stars are particularly favorable targets for high precision astrometry. Aims. We aim to characterize the presence of physical companions of stellar and substellar mass in orbit around nearby stars. Methods. Orbiting secondary bodies influence the proper motion of their parent star through their gravitational reflex motion. Using the HIPPARCOS and Gaia’s second data release (GDR2) catalogs, we determined the long-term proper motion of the stars common to these two catalogs. We then searched for a proper motion anomaly (PMa) between the long-term proper motion vector and the GDR2 (or HIPPARCOS) measurements, indicative of the presence of a perturbing secondary object. We focussed our analysis on the 6741 nearby stars located within 50 pc, and we also present a catalog of the PMa for ≳99% of the HIPPARCOS catalog (≈117 000 stars). Results. 30% of the stars studied present a PMa greater than 3σ. The PMa allows us to detect orbiting companions, or set stringent limits on their presence. We present a few illustrations of the PMa analysis to interesting targets. We set upper limits of 0.1−0.3 MJ to potential planets orbiting Proxima between 1 and 10 au (Porb = 3 to 100 years). We confirm that Proxima is gravitationally bound to α Cen. We recover the masses of the known companions of ϵ Eri, ϵ Ind, Ross 614 and β Pic. We also detect the signature of a possible planet of a few Jovian masses orbiting τ Ceti. Conclusions. Based on only 22 months of data, the GDR2 has limitations. But its combination with the HIPPARCOS catalog results in very high accuracy PMa vectors, that already enable us to set valuable constraints on the binarity of nearby objects. The detection of tangential velocity anomalies at a median accuracy of σ(ΔvT) = 1.0 m s−1 per parsec of distance is already possible with the GDR2. This type of analysis opens the possibility to identify long period orbital companions otherwise inaccessible. For long orbital periods, Gaia’s complementarity to radial velocity and transit techniques (that are more sensitive to short orbital periods) already appears to be remarkably powerful.

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Combining high-contrast imaging and radial velocities to constrain the planetary architectures of nearby stars

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935733 ◽

2019 ◽

Vol 630 ◽

pp. A50 ◽

Cited By ~ 2

Author(s):

A. Boehle ◽

S. P. Quanz ◽

C. Lovis ◽

D. Ségransan ◽

S. Udry ◽

...

Keyword(s):

Parameter Space ◽

Major Axis ◽

Solar Neighborhood ◽

High Contrast ◽

Contrast Imaging ◽

Semi Major Axis ◽

Detection Techniques ◽

High Contrast Imaging ◽

Nearby Stars ◽

Substellar Companions

Context. Nearby stars are prime targets for exoplanet searches and characterization using a variety of detection techniques. Combining constraints from the complementary detection methods of high-contrast imaging (HCI) and radial velocity (RV) can further constrain the planetary architectures of these systems because these methods place limits at different regions of the companion mass and semi-major axis parameter space. Compiling a census of the planet population in the solar neighborhood is important to inform target lists for future space missions that will specifically target nearby stars to search for Earth analogs. Aims. We aim to constrain the planetary architectures from the combination of HCI and RV data for six nearby stars within 6 pc: τ Ceti, Kapteyn’s star, AX Mic, 40 Eri, HD 36395, and HD 42581. We explored where HCI adds information to constraints from the long-term RV monitoring data for these stars. Methods. We compiled the sample from stars with available archival VLT/NACO HCI data at L′ band (3.8 μm), where we expect substellar companions to be brighter for the typically older ages of nearby field stars (>1 Gyr). The NACO data were fully reanalyzed using the state-of-the-art direct imaging pipeline PynPoint and combined with RV data from HARPS, Keck/HIRES, and CORALIE. A Monte Carlo approach was used to assess the completeness in the companion mass and semi-major axis parameter space from the combination of the HCI and RV data sets. Results. We find that the HCI data add significant information to the RV constraints, increasing the completeness for certain companions masses and semi-major axes by up to 68–99% for four of the six stars in our sample, and by up to 1–13% for the remaining stars. The improvements are strongest for intermediate semi-major axes (15–40 AU), corresponding to the semi-major axes of the ice giants in our own solar system. The HCI mass limits reach 5–20 MJup in the background-limited regime, depending on the age of the star. Conclusions. Through the combination of HCI and RV data, we find that stringent constraints can be placed on the possible substellar companions in these systems. Applying these methods systematically to nearby stars will quantify our current knowledge of the planet population in the solar neighborhood and inform future observations.

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