Astrometry Archives

Fitting of exoplanets. (a) The target star is HD 88230, with a hypothetical Earth-like planet placed at a distance of 1 AU from the star. (b) The target star is again HD 88230, with a hypothetical warm Jupiter placed at a distance of 0.1 AU. (c) The target star is HD 147513, which is known to host the detected Jovian planet HD 147513 b. The angular distance measurement accuracy is 1 µas. The black points represent the simulated planetary parameters, while the red points show the residuals after removing proper motion and parallax through fitting. The blue points depict the stellar motion orbit induced by planetary perturbations, derived from a Keplerian fit to the residuals. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Status Report, Stellar Cartography

Closeby Habitable Exoplanet Survey (CHES). V. Planetary Parameters Derived from Angular Separation Variations

by Keith CowingApril 1, 2026April 1, 2026

The Closeby Habitable Exoplanet Survey (CHES) aims to achieve microarcsecond-level astrometry of about one hundred nearby FGK-type stars within 10 parsecs to detect Earth-like planets.

TRES RV observations of HD 12800. We mark the dates of announcement (2022-06-13) and official retraction (2024-05-27) for the Gaia DR3 planet candidate. Our observations would have easily detected the RV signal expected from the Gaia DR3 orbital solution, and independently verify that the companion does not exist. While in this case the ultimate result is a non-detection, this nonetheless serves to demonstrate the value of intermediate-precision (≈10 m s−1 ) RV observations for the follow-up of Gaia astrometric exoplanet candidates. -- astro-ph.EP)

Astronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report, Stellar Cartography

A Planetary Illusion’s Funeral: Non-detection of a Gaia DR3 Exoplanet Candidate, and the Role of Intermediate-precision Radial Velocities in Gaia Exoplanet Follow-up

by Keith CowingMarch 28, 2026March 28, 2026

The detection of exoplanets using astrometry has long been an area of interest, but is fraught with challenges. The Gaia mission is fundamentally reshaping this field thanks to its unprecedentedly […]

The strength of indirect detection signals from an Earth-like exoplanet as a function of stellar effective temperature. Bands encompassing main sequence spectral classes A through M color coded by temperature are indicated at the top. Here, Earth-like is defined as a 1-Earth mass object in an orbit receiving irradiance equivalent to 1 AU from our Sun (the solar constant). Radial Velocity signals (solid blue line) are seen to exhibit a rapid rise in signal strength (given on the right-hand abscissa) for cooler, M dwarf systems where they become detectable with present submeter per second RV precision. On the other hand, astrometric deflection signals (colored diamond symbols) rise with host star temperature, and decline linearly with distance from values of up to several microarcseconds for the nearest stars. For convenience the plot also indicates the size of the temperate orbit modeled (in AU, left abscissa) and its corresponding orbital period (in years, also left abscissa). -- astro-ph.IM

Alpha Centauri, Astronomy & Telescopes, Biosignatures & Paleobiology, Cubesats and smallsats, Habitable Zones, Imaging & Spectroscopy, Missions & Hardware, Status Report

The TOLIMAN Mission: A Low-cost Space Telescope For High Precision Narrow-angle Astrometry

by Keith CowingMarch 18, 2026March 18, 2026

The TOLIMAN project is engaged with the construction, launch and operation of a low-cost space telescope of unorthodox optical design. Its primary science goal targets an exhaustive search for temperate-orbit […]

Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Gaia Mission, Imaging & Spectroscopy, Proxima Centauri, Status Report, Stellar Cartography

Astrometric Reconnaissance of Exoplanetary Systems (ARES). I. Methodology Validation With HST Point-source Images Of Proxima Centauri

by Keith CowingDecember 16, 2025December 16, 2025

We present the first results of the Astrometric Reconnaissance of Exoplanetary Systems (ARES) project, aimed at validating and characterizing candidate exoplanets around the nearest systems using multi-epoch Hubble Space Telescope […]

Image of HIP 71618 B (indicated by the arrow) taken by the Subaru Telescope. The planet’s host star has been blocked in this image. The star’s position is indicated by the star mark. The high resolution image and the image without text are available from the links. (Credit: T. Currie/Subaru Telescope, UTSA)

AI - Data - Apps - Cybernetics, Astronomy & Telescopes, Brown Dwarfs, Exoplanets, -moons, -comets, Gas Giants, Imaging & Spectroscopy, Press Release

First Results From The Subaru Telescope’s OASIS Survey: Direct Imaging Of New Worlds Around Unexplored Stars

by Keith CowingDecember 7, 2025December 7, 2025

The discovery of two remarkable substellar companions orbiting distant stars has been announced by an international team of astronomers using the Subaru Telescope’s sharp adaptive-optics imaging together with precision stellar […]

Analytical predictions for the astrometric effect of a moon with varying mass and distance to HD 206893 B. GRAVITY could in principle detect moons lower than a Neptune mass at larger periods. The fit of the GRAVITY data is shown as a green point assuming the mass and period as upper limits in our tentative detection. The orange area shows the plausible parameter space where a moon could be located, and still be potentially detectable with GRAVITY assuming an astrometric accuracy of 10 µas (see section 3.3). -- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

Exomoon Search With VLTI/GRAVITY Around The Substellar Companion HD 206893 B

by Keith CowingNovember 26, 2025June 10, 2026

Direct astrometric detection of exomoons remains unexplored. This study presents the first application of high-precision astrometry to search for exomoons around substellar companions.

Masses and semi-major axes for known planets and simulated Gaia planets. In both cases, we have restricted the sample to planets with Porb and mp constrained to within 20% (i.e., P84th/P16th < 1.2 and m84th/m16th < 1.2). Blue and green points show known planets discovered with the Doppler and transit methods. Red and black points are from our mock Gaia planet catalogs for DR4 and DR5 (see Section 4). For comparison, the values of Jupiter and Saturn are highlighted with gray points labeled “J” and “S.” The Gaia planets are primarily super-Jupiters on multi-AU orbits. About 100 such planets are currently known; Gaia promises to expand this sample to thousands in DR4 and tens of thousands in DR5. -- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Gaia Mission, Imaging & Spectroscopy, Press Release, Stellar Cartography

On The Exoplanet Yield Of Gaia Astrometry

by Keith CowingNovember 18, 2025November 18, 2025

We re-examine the expected yield of Gaia astrometric planet detections using updated models for giant-planet occurrence, the local stellar population, and Gaia’s demonstrated astrometric precision.

A possible Focal Plane dedicated instrument for HWO. Upper left panel: HWO telescope configuration for Exploratory Architecture Concepts) EAC1. Upper right panel : location of the focal plane and the detectur Calibration unit in the EAC1 case. Bottom left panel : location of the focal plane and the detector Calibration unit in the EAC3 case. Bottom right panel : possible focal plane concept with 4 GigaPyx 220M detectors and a central GigaPyx 14M detector. -- astro-ph.IM

Astronomy & Telescopes, Exoplanets, -moons, -comets, Gaia Mission, Habitable Zones, Imaging & Spectroscopy, Status Report, Stellar Cartography

Very High Precision Astrometry for Exoplanets and Dark Matter with the Habitable Worlds Observatory

by Keith CowingNovember 2, 2025November 2, 2025

Astrometry, one of the oldest branches of astronomy, has been revolutionized by missions like Hipparcos and especially Gaia, which mapped billions of stars with extraordinary precision.

Alpha Centauri, Astronomy & Telescopes, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Gas Giants, Habitable Zones, Imaging & Spectroscopy, Status Report, Stellar Cartography

Seeking The Worlds Of Avatar: Prospects for Detecting Moons Orbiting a Giant Planet in Alpha Centauri A’s Habitable Zone

by Keith CowingSeptember 22, 2025September 22, 2025

Nearby giant exoplanets offer an opportunity to search for moons (exomoons) orbiting them. Here, we present a simulation framework for investigating the possibilities of detecting exomoons via their astrometric signal […]

Scientists have found thousands of exoplanets (planets outside our solar system) throughout the galaxy. Most can be studied only indirectly, but scientists know they vary widely, as depicted in this artist’s concept, from small, rocky worlds and gas giants to water-rich planets and those as hot as stars. Credit: NASA’s Goddard Space Flight Center Larger image

Astronomy & Telescopes, Exoplanets, -moons, -comets, Press Release

NASA’s Exoplanet Discovery Exceeds 6,000 Worlds

by Keith CowingSeptember 17, 2025September 17, 2025

The official number of exoplanets — planets outside our solar system — tracked by NASA has reached 6,000. Confirmed planets are added to the count on a rolling basis by […]

Astrometry

Closeby Habitable Exoplanet Survey (CHES). V. Planetary Parameters Derived from Angular Separation Variations

A Planetary Illusion’s Funeral: Non-detection of a Gaia DR3 Exoplanet Candidate, and the Role of Intermediate-precision Radial Velocities in Gaia Exoplanet Follow-up

The TOLIMAN Mission: A Low-cost Space Telescope For High Precision Narrow-angle Astrometry

Astrometric Reconnaissance of Exoplanetary Systems (ARES). I. Methodology Validation With HST Point-source Images Of Proxima Centauri

First Results From The Subaru Telescope’s OASIS Survey: Direct Imaging Of New Worlds Around Unexplored Stars

Exomoon Search With VLTI/GRAVITY Around The Substellar Companion HD 206893 B

On The Exoplanet Yield Of Gaia Astrometry

Very High Precision Astrometry for Exoplanets and Dark Matter with the Habitable Worlds Observatory

Seeking The Worlds Of Avatar: Prospects for Detecting Moons Orbiting a Giant Planet in Alpha Centauri A’s Habitable Zone

NASA’s Exoplanet Discovery Exceeds 6,000 Worlds

Tricorder Tech: New Handheld Device Maps Chemical Composition Using Infrared Light

No Statistically Significant Evidence For A Correlation Between Stellar And planetary Composition

Water Planet Recon: How Accurately Can We Measure Earth Ocean’s Deepest Point?

Webb Reveals A Stunning Panorama Of Star Formation

Deep Learning of SHERLOC Raman Spectra For Facilitating Mars Astromaterial Identification