transit Archives - Astrobiology

Measured effective height of Earth’s atmosphere over the SPIRou wavelength range. The surface area, S , is derived from astrometry.

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report

Earth As A Transiting Exoplanet

by Keith CowingJune 9, 2026June 10, 2026

Context. Detecting and characterizing the atmosphere of rocky planets in the habitable zone is a key objective of exoplanet research in the era of JWST and the upcoming E-ELT. Spectroscopy […]

Top – the total planetary flux as measured in flux units for cloud-free planetary atmospheres. Bottom – the percent contribution of reflected light to the total flux as a function of wavelength (R = 300). Colored bands in the top panel show the photometric (hashed) and spectroscopic (solid) coverage from current and future facilities over this wavelength range. Figure updated from Mayorga + (2019) and included with permission of L. C. Mayorga. -- astro-ph.IM

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

Transiting Exoplanets As The Immediate Future For Population-level Atmospheric Science

by Keith CowingJanuary 17, 2026January 17, 2026

The transit method, during which a planet’s presence is inferred by measuring the reduction in flux as it passes in front of its parent star, is a highly successful exoplanet […]

The transit of Venus across the sun on 5 June 2012 observed in 5 SDO channels. The black dots represent the path of Venus and do not depict the actual planet size or the cadence at which it was observed. Top row shows the images obtained in 6173Å and 1700Å channels; bottom row shows the images obtained in 304Å, 171Å, and 94Å channels respectively. -- astro-ph.EP

Analog Studies, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report, Venus

Venus As An Exoplanet Analog: Extended UV Transit Signatures And Coronal Occultations

by Keith CowingDecember 10, 2025December 10, 2025

Stellar activity manifests differently across wavelengths, causing flux variability that can obscure planetary transits. While transit observations are typically performed in the visible and infrared bands, where stellar flux is […]

Synthetic, monochromatic light curves of a comet with narrow tail, plotted for the three selected grain size distributions, labelled as a ∼ 2 µm (top row), 650 nm (middle row) and 200 nm (bottom row), for an A star. Columns denote the materials used in the simulations: carbon (left), graphite (second from the left), pyroxene (second from the right), and olivine (right). Note the change in the scale of the y axis from row to row. -- astro-ph.EP

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

Exocomet Models in Transit: Light Curve Morphology in the Optical — Near Infrared Wavelength Range

by Keith CowingMay 24, 2024

Following the widespread practice of exoplanetary transit simulations, various presumed components of an extrasolar system can be examined in numerically simulated transits, including exomoons, rings around planets, and the deformation […]

CO2 transit spectra for aquaplanets from Group C with varying pN2 (purple), Group A (black), and Group B with 0.1 bar CO2. Although the Group B simulation has two orders of magnitude more CO2, its transit amplitude is smaller than those of the Group C simulations due to the geometries of the systems. However, note that our GCM simulations only include a troposphere; if CO2 is well-mixed on a real planet, spectral features could extend much higher. -- astro-ph.EP

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

Water Vapour Transit Ambiguities for Habitable M-Earths

by Keith CowingFebruary 21, 2024February 20, 2024

We have shown in a recent study, using 3D climate simulations, that dayside land cover has a substantial impact on the climate of a synchronously rotating temperate rocky planet such […]

Rate of true positives for the 4000 simulated light curves. The color scale represents the fraction of true positives, white if all injected transits are recovered in a given portion of the (τ, δ) parameter space, black if none are recovered. -- astro-ph.EP

AI - Data - Apps - Cybernetics, Astronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

nuance: Efficient Detection Of Planets Transiting Active Stars

by Keith CowingFebruary 14, 2024February 14, 2024

The detection of planetary transits in the light curves of active stars, featuring correlated noise in the form of stellar variability, remains a challenge. Depending on the noise characteristics, we […]

Idealized Doppler and transit surveys. The top panel shows the results of a Doppler survey in which 100 Sun-like stars are each observed 50 times over one year with 1 m s−1 precision. The bottom panel shows the results of a transit survey in which 104 stars are observed continuously for a year with a photometric precision corresponding to 3×10−5 per 6 hours of data. Each star is assumed to have one planet on a randomly-oriented circular orbit, with random properties drawn from log-uniform distributions between the plotted limits. Colored points are planets detected with a signal-to-noise ratio (SNR) exceeding 10. Gray points are undetected planets. In the Doppler survey, the threshold mass scales as P 1/3 for periods shorter than the survey duration. For longer periods, the threshold mass increases more rapidly, with an exponent depending on the desired false-alarm probability (Cumming 2004). The transit survey includes more stars, because they can be monitored simultaneously, but detects a smaller fraction of the planets and is more strongly biased toward short periods. For periods shorter than survey duration, the threshold radius varies as P 1/6 (Pepper et al. 2003). For longer periods it is impossible to observe more than one transit, making any detections more ambiguous. -- astro-ph.EP

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

Planet Occurrence From Doppler And Transit Surveys

by Keith CowingFebruary 1, 2024February 1, 2024

Prior to the 1990s, speculations about the occurrence of planets around other stars were based only on planet formation theory, observations of circumstellar disks, and the knowledge that at least […]

Left: HAT-P-33b observational and theoretical light curves using TESS sector 45 data; Right: The observational light curve of HAT-P-32b from this study in the 𝑉 filter and the theoretical light curve. -- astro-ph.EP

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

Ephemeris Updates For Seven Selected HATNet Survey Transiting Exoplanets

by Keith CowingJune 2, 2023June 2, 2023

We refined the ephemeris of seven transiting exoplanets HAT-P-6b, HAT-P-12b, HAT-P-18b, HAT-P-22b, HAT-P-32b, HAT-P-33b, and HAT-P-52b. We observed 11 transits from eight observatories in different filters for HAT-P-6b and HAT-P-32b.

Black crosses: TESS lightcurve around the transits of planet b, after phasing by the planet’s period against the adopted ephemeris and the correction against gradients in the off-eclipse sections (indicated by the orange vertical dashed lines) as described in Sect. 2. Green crosses: The same curve, after a boxcar smoothing over 100 phased data points and posterior binning over 50 points. We note that the average time-increment between the binned points is 126 seconds, which is very similar to the 120 s temporal resolution of TESS lightcurves. The red curve is the transit model generated with UTM/UFIT, described in Appendix C. -- astro-ph.EP

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

TOI-1416: A Ssystem With A Super-Earth Planet With A 1.07d Period

by Keith CowingMay 31, 2023May 31, 2023

TOI 1416 (BD+42 2504, HIP 70705) is a V=10 late G or early K-type dwarf star with transits detected by TESS. Radial velocities verify the presence of the transiting planet […]

TESS objects of interest

Astronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report, TRAPPIST-1

EDEN Survey: Small Transiting Planet Detection Limits and Constraints on the Occurrence Rates for Late M Dwarfs within 15 pc

by Keith CowingFebruary 8, 2023February 8, 2023

Earth-sized exoplanets that transit nearby, late spectral type red dwarfs will be prime targets for atmospheric characterization in the coming decade.