Exoplanetology: Exoplanets & Exomoons

Detecting Solar System Analogs Through Joint Radial Velocity/Astrometric Surveys

By Keith Cowing

Status Report

astro-ph.EP

February 12, 2023

Filed under astro-ph.EP, Astrometry, exoplanet, Gaia, habitability, telescope, Terra Hunting Experiment

Detecting Solar System Analogs Through Joint Radial Velocity/Astrometric Surveys — [Left] RV signal for Earth-mass, Jupiter-mass, and Saturn-mass objects on Earth-like, Jupiter-like, and Saturn-like eccentric orbits, respectively, around a Solar mass star with varying orbital periods. THE is pushing towards the 0.1 m/s detection limit for Earth-like exoplanets, with 10 years of nightly observations with target 1σ measurement error of ∼0.3 m/s per observation. [Right] Astrometric signal for Earth-mass, Jupiter-mass, and Saturn-mass objects around Solar mass stars with varying periods on circular orbits. Gaia astrometry will have a ∼60 µas 1σ measurement error per observation for bright stars. Roman astrometry has a target ∼5-20 µas 1σ measurement error per observation for bright stars. With Gaia and Roman, the astrometric observations can have a baseline of up to ∼25 years. As the radial velocity signal increases with shorter orbital periods and the astrometric signal increases with larger orbital periods, we can see how the two observing methods are complementary in period space. We emphasise that these (target) measurement errors are not a detection threshold, but rather a per observation estimated measurement error. — astro-ph.EP

Earth-mass exoplanets on year-long orbits and cool gas giants (CGG) on decade-long orbits lie at the edge of current detection limits.

In our Solar System, the two CGGs, Jupiter and Saturn, played a critical role in the formation, evolution, and habitability of Earth. The Terra Hunting Experiment (THE) will take nightly radial velocity (RV) observations on HARPS3 of at least 40 bright nearby G and K dwarfs for 10 years, with a target 1σ measurement error of ∼0.3 m/s, in search of exoplanets that are Earth-like in mass and temperature. Gaia will soon release 100-200 astrometric observations of the THE stars with a 10 year baseline and ∼60 μas 1σ measurement error.

The Nancy Grace Roman Space Telescope will be capable of precision astrometry using its wide field imager (target ∼5-20 μas 1σ measurement error for bright stars) and could extend the astrometric observational baseline of Gaia to ∼25 years. We simulate and model an observing program that combines data from these three telescopes.

We find that (1) THE RVs and Gaia astrometry can detect Earth-like and CGG-like exoplanets around bright Sun-like stars at 10 parsecs and that (2) adding Roman astrometry (subject to our observing assumptions described below) improves the detection precision for CGG masses by a factor up to ∼6 and periods by a factor up to ∼5. Such a survey could provide insight into the prevalence of Solar System analogous exoplanetary architectures for bright nearby G and K dwarfs.

Daniel A. Yahalomi, Ruth Angus, David N. Spergel, Daniel Foreman-Mackey

Comments: 19 pages, 10 figures. Submitted to AAS Journals
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2302.05064 [astro-ph.EP] (or arXiv:2302.05064v1 [astro-ph.EP] for this version)
Submission history
From: Daniel Yahalomi A
[v1] Fri, 10 Feb 2023 05:48:20 UTC (5,733 KB)
https://arxiv.org/abs/2302.05064
Astrobiology

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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