Keck Observatory Archives - Astrobiology

A New Window into Planet Formation

Astrogeology, Atmospheres, Climate, Weather, Brown Dwarfs, Exoplanets, -moons, -comets, Gas Giants, Ice Giant, Icy Worlds, Press Release, Stellar Cartography, Water/Hycean Worlds & Oceanography

A New Spin On Planet Formation

by Keith CowingMarch 21, 2026March 21, 2026

Astronomers using the W. M. Keck Observatory on Maunakea, Hawaiʻi Island, have confirmed a long-predicted relationship between planetary mass and rotation.

A] Example Keck NIRSPEC slit obtained on February 24, 2016, when 18.6◦W (labeled with the black dot) is in the morning (∼13 hours prior to local noon in Europa’s ∼85-hour day, estimated ∼103 K). [B] Example Keck NIRSPEC slit obtained on February 25, 2016, when the same region (18.5◦W; labeled with the red dot) is in the afternoon (∼16 hours after local noon in Europa’s ∼85-hour day, estimated ∼115 K). [C] Corresponding reflectance spectra for this location in the morning (in black) and in the afternoon (in red). Dashed gray lines outline the H2O2 band. Second-order polynomial continua are indicated by the dashed curves of the same color as the spectrum. Continuum-removed absorptions are included and show nearly overlapping absorptions. A ∼12 K temperature increase over 24 hours is estimated from the thermal model of Trumbo et al. (2017a). This temperature change results in a negligible -3.1% change in the integrated band areas. Leading chaos regions are outlined in black (Leonard et al. 2024). Background basemap credit: USGS (2002). -- astro-ph.EP

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Europa, Icy Worlds, Imaging & Spectroscopy, Status Report, Water/Hycean Worlds & Oceanography

Europa’s H2O2: Temperature Insensitivity and a Correlation with CO2

by Keith CowingAugust 29, 2024August 28, 2024

H2O2 is part of Europa’s water-ice radiolytic cycle and a potential source of oxidants to Europa’s subsurface ocean. However, factors controlling the concentration of this critical surface species remain unclear.

The Keck Planet Imager and Characterizer (KPIC) connects the Keck II AO system and the Keck/NIRSPEC high-resolution infrared spectrograph (https://www2.keck.hawaii.edu/inst/nirspec/) via a linear bundle of four single-mode fibers spaced by ~800 mas on the sky. Single-mode fibers provide a more stable quasi-Gaussian line spread function. Their small angular size, matched to the diffraction limit (FWHM~50 mas in K band), also provides excellent sky background rejection, as well as reduces the off-axis starlight injection into the single mode fibers. Currently, KPIC uses the Shack-Hartmann Wavefront Sensors for AO. Larger image

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

The High-contrast Performance of the Keck Planet Imager and Characterizer

by Keith CowingJune 24, 2024June 24, 2024

The Keck Planet Imager and Characterizer (KPIC), a series of upgrades to the Keck II Adaptive Optics System and Instrument Suite, aims to demonstrate high-resolution spectroscopy of faint exoplanets that […]

TIC365102760 b

Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Gas Giants, Imaging & Spectroscopy, Press Release

Weird New Planet Retained An Atmosphere Despite Its Nearby Star’s Relentless Radiation

by Keith CowingJune 6, 2024

A rare exoplanet that should have been stripped down to bare rock by its nearby host star’s intense radiation somehow grew a puffy atmosphere instead—the latest in a string of […]

The TESS-Keck Survey XX

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

The TESS-Keck Survey XX: 15 New TESS Planets and a Uniform RV Analysis of all Survey Targets

by Keith CowingMay 27, 2024May 27, 2024

The Transiting Exoplanet Survey Satellite (TESS) has discovered hundreds of new worlds, with TESS planet candidates now outnumbering the total number of confirmed planets from Kepler.

Representation of TOI-1437 b as it falls on a mass-radius diagram (large black circle). Individual solid lines are theoretical mass-radius curves for planets whose composition is specified in the figure legend. Light grey circles indicate the population of planets between 1.0-3.5 R⊕ that have measured masses. -- astro-ph.EP

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

The TESS-Keck Survey. XXII. A sub-Neptune Orbiting TOI-1437

by Keith CowingMay 22, 2024May 22, 2024

Exoplanet discoveries have revealed a dramatic diversity of planet sizes across a vast array of orbital architectures. Sub-Neptunes are of particular interest; due to their absence in our own solar […]

The mass-radius diagram for small planets. Data comes from the NASA Exoplanet Archive’s planetary systems table, as accessed on 2022-Nov-17 (NASA Exoplanet Archive 2022). Planets with mass and radius measurements to better than 50% and 15% fractional precision, respectively, are shown as the circles with 1σ error bars. The opacity of the points is proportional to mass measurement precision (i.e., a less precise mass measurement translates to a more transparent marker). Color corresponds to equilibrium temperature assuming zero Bond albedo and full day-night heat redistribution. Underlying contours come from Gaussian kernel density estimation (KDE) of the confirmed planets described above. The 11 transiting planets from this work are overplotted as the stars. Mass upper limits (98% confidence) are plotted for HD 25463 c (yellow star near the radius valley) and HIP 9618 c (labeled). A handful of composition curves are plotted for reference (Lopez & Fortney 2014; Zeng et al. 2016, 2019). The curves of H/He envelopes atop Earth-like cores come from Lopez & Fortney (2014) and are chosen for a planet receiving 10× Earth’s incident flux (i.e., Teq ≈ 500 K) orbiting a 10 Gyr-old, solar-metallicity star. The 50% water plus 50% Earth-like composition curve from Zeng et al. (2019) is calculated for a fixed temperature of 700 K at 100 bar, which determines the planetary model’s specific entropy. Note that familiar features of the planet radius distribution are now visible as two-dimensional features in the mass-radius plane. These include the radius valley (Fulton et al. 2017; Van Eylen et al. 2018), with center near 6 M⊕ and 1.8 R⊕, and the radius cliff (e.g., Kite et al. 2019), as seen by in the steep drop off in the number of planets around 3 R⊕. -- astro-ph.EP

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

The TESS-Keck Survey. XVI. Mass Measurements for 12 Planets in Eight Systems

by Keith CowingJune 29, 2023June 29, 2023

With JWST’s successful deployment and unexpectedly high fuel reserves, measuring the masses of sub-Neptunes transiting bright, nearby stars will soon become the bottleneck for characterizing the atmospheres of small exoplanets […]

mini-Neptune TOI 560.01

Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Habitable Zones, Press Release

Puffy Planets Can Lose Their Atmospheres And Become Super-Earths

by Keith CowingMarch 7, 2023March 7, 2023

If our solar system were a hobbyist kit, it would come boxed up with four rocky terrestrial planets, like Earth; and four gas giant planets like Jupiter.

Astrochemistry, Press Release

Substantial Oxygen Detected In An Ancient Star's Atmosphere

by Keith CowingJanuary 23, 2020

An international team of astronomers from the University of California San Diego, the Instituto de Astrofísica de Canarias (IAC), and the University of Cambridge have detected large amounts of oxygen […]

Habitable Zones, Press Release

Looking for Signs of Alien Life On HR 8799c

by Keith CowingNovember 20, 2018

Astronomers have gleaned some of the best data yet on the composition of a planet known as HR 8799c — a young giant gas planet about 7 times the mass […]