Stellar Cartography Archives

Expected Doppler semiamplitude imparted on a solar-mass host star by a super-Earth with orbital period P = 2 days and Rp = 1.6 R⊕ as a function of core-mass fraction superimposed on the S. S. Brems et al. (2019) relationship between stellar age and radial velocity jitter. The solid blue line is the maximum-likelihood S. S. Brems et al. (2019) relationship while the light blue polygon is the 16th to 84th interquantile range; the horizontal black lines indicate the Doppler semiamplitudes imparted by the hypothesized super-Earths. We find that while high core-mass fraction super-Earths can be detected in the presence of radial velocity jitter at all ages, low core-mass fraction super-Earths can only be detected orbiting host stars with ages in excess of 5 Gyr. This observational bias against the detection of low core-mass fraction terrestrial exoplanets orbiting young stars can easily explain the statistically significant inverse correlation identified by A. Weeks et al. (2025) between host star age and either the logarithm of planet density or iron-mass fraction. -- astro-ph.EP

Astrochemistry, Astrogeology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report, Stellar Cartography

Terrestrial Planets In Mean-motion Resonances Are Water Rich

by Keith CowingAugust 26, 2025

Exoplanet Mass And Radius Inferences Fundamentally Rely On Host Star Mass And Radius Inferences.

Snapshot of the triple transit of planet b, c, and d as seen by K2 at the end of 2016. This artistic representation has been created with the software tango (https://github.com/oscaribv/tango).

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

Discovery Of A Multi-planetary System Orbiting The Aged Sun-like Star HD 224018

by Keith CowingAugust 23, 2025August 23, 2025

In 2016, Kepler/K2 detected a system of two sub-Neptunes transiting the star HD 224018, one of them showing a mono-transit event.

Best-fitting relative brightness distribution of the Sun for each of the 23 chunks listed in Tab. 1 and shown in Fig. 1. The color scale depicts the logarithm of the relative surface brightness. All maps are shown at a solar rotation phase of 0, computed using Eq. 2, and the chunk number is indicated on top of each map. -- astro-ph.EP

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

Using Doppler Imaging To Model Stellar Activity And Search For Planets Around Sun-like Stars

by Keith CowingAugust 20, 2025August 20, 2025

Doppler Imaging (DI) is a well-established technique to map a physical field at a stellar surface from a time series of high-resolution spectra.

Cosmic Shoreline for all known planetary systems orbiting M-dwarf-type stars. The black dashed-dotted line is our newly proposed Empirical Cosmic Shoreline (ECS), same as in Figure 1. The gray points mark the systems whose atmospheres have not been studied; the orange ones mark the planets with reported strong non-detections; and the green ones mark the planets with a (tentative) atmosphere detection. -- astro-ph.EP

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

An Empirical Determination Of The Cosmic Shoreline

by Keith CowingAugust 19, 2025August 19, 2025

The Cosmic Shoreline concept was introduced as a way to separate planets with and without atmosphere, based on the relationship between the cumulative instellation and the escape velocity observed in […]

LEFT: Predicted 22Ne mass fraction as a function of metallicity for the WD remnants of stars in the Hypatia Catalog (Hinkel et al. 2014). The colors represent [N/H] for the same stars. MIDDLE and RIGHT: C and N abundances of the same stars from the Hypatia Catalog. The color bars represent the predicted neon mass fraction, X(22Ne), in their remnants. Two chemically peculiar low-metallicity objects, BD+80 245 and HD 19445, are labeled and marked as stars. -- astro-ph.SR

Astronomy & Telescopes, Habitable Zones, Imaging & Spectroscopy, Status Report, Stellar Cartography

The Fraction Of Distilled White Dwarfs With Long-Lived Habitable Zones

by Keith CowingAugust 19, 2025

After carbon and oxygen, 22Ne is the most abundant element in white dwarf interiors. As C/O white dwarfs (WDs) crystallize, they are predicted to go through a distillation process in […]

Comparison of elemental abundances from the literature and this work (filled circles) for the same stars. The y-axis shows the difference in abundance, [X/H]literature – [X/H]this work, plotted against the Tc of each element on the x-axis. Potassium (K) is excluded as it was not reported in the literature. The open squares and downward triangles show a direct comparison of abundances measured from HARPS and MIKE spectra using the same spectral lines and analysis methods applied in this study. The differences reflect both instrumental systematics and manual measurement variability between HARPS and MIKE. -- astro-ph.EP

Analog Studies, Astrochemistry, Astrogeology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report, Stellar Cartography

Planets Around Solar Twins/Analogs (PASTA) II: Chemical Abundances, Systematic Offsets, And Clues To Planet Formation

by Keith CowingAugust 14, 2025August 14, 2025

Context. Previous studies have suggested that the Sun is relatively depleted in refractory elements compared to other solar twins or analogs, potentially as a result of planet formation. However, such […]

Planet occurrence rates as a function of stellar temperature for short-period (P = 1 − 40 days) super-Earths (green squares) and sub-Neptunes (blue circles). A power law was fit to the super-Earths, and a double broken power law was fit to the sub-Neptunes, showing two breaks: TBr,1 = 3750+153 −97 K and TBr,2 = 5758+94 −145 K. The short-period sub-Neptunes peak around a host type of M0.5 V, then decrease in planet occurrence toward cooler M dwarfs. G and K-type stars have comparable rates of short-period super-Earths and sub-Neptunes. Another noticeable decrease in sub-Neptunes happens for host stars hotter than the Sun. Short-period super-Earths increase in occurrence toward cooler stars, with no discernible peak in the host star temperatures for which we have data from Kepler and K2. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Status Report, Stellar Cartography

Scaling K2 VIII: Short-Period Sub-Neptune Occurrence Rates Peak Around Early-Type M Dwarfs

by Keith CowingAugust 13, 2025August 13, 2025

We uniformly combined data from the NASA Kepler and K2 missions to compute planet occurrence rates across the entire FGK and M dwarf stellar range.

The average T Tauri (top) and VLMS (bottom) sample JWST spectra. The detected molecular species are highlighted. The C2H2 and H2O regions (yellow and blue, respectively) show the regions over which the fluxes are integrated. Most of the unlabeled lines in the T Tauri average are various H2O transitions. -- astro-ph.EP

Astrochemistry, Astronomy & Telescopes, Biosignatures & Paleobiology, Imaging & Spectroscopy, Press Release, Stellar Cartography

A Transition From H2O To C2H2 Dominated Spectra With Decreasing Stellar Luminosity

by Keith CowingAugust 7, 2025

The chemical composition of the inner regions of disks around young stars will determine the properties of planets forming there.

About a third of the 49 young isolated stars surveyed by the researchers were found to be misaligned with their protoplanetary disk. Photo Credit Lauren Biddle, The University of Texas at Austin

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

Some Young Suns Align With Their Planet-forming Disks, Others Are Born Tilted

by Keith CowingAugust 7, 2025August 7, 2025

Researchers at UC Santa Barbara, The University of Texas at Austin, Yale University and National Taiwan Normal University have found that a fair number of sun-like stars emerge with their […]

Schematic presentation of the system showing the binary star and the two planets orbiting the primary. The primary star is at the origin of the coordinate system. The indices I, O, S refer to the inner and outer planet, and the secondary star, respectively. -- astro-ph.EP

Exoplanets, -moons, -comets, Status Report, Stellar Cartography

Secular Resonances in Planet-Hosting Binary Stars. I. General Theory

by Keith CowingAugust 1, 2025August 1, 2025

Motivated by the diversity of circumstellar planets in binary stars and the strong effects of the secular resonances of Jupiter and Saturn on the formation and architecture of the inner […]

Stellar Cartography

Terrestrial Planets In Mean-motion Resonances Are Water Rich

Discovery Of A Multi-planetary System Orbiting The Aged Sun-like Star HD 224018

Using Doppler Imaging To Model Stellar Activity And Search For Planets Around Sun-like Stars

An Empirical Determination Of The Cosmic Shoreline

The Fraction Of Distilled White Dwarfs With Long-Lived Habitable Zones

Planets Around Solar Twins/Analogs (PASTA) II: Chemical Abundances, Systematic Offsets, And Clues To Planet Formation

Scaling K2 VIII: Short-Period Sub-Neptune Occurrence Rates Peak Around Early-Type M Dwarfs

A Transition From H2O To C2H2 Dominated Spectra With Decreasing Stellar Luminosity

Some Young Suns Align With Their Planet-forming Disks, Others Are Born Tilted

Secular Resonances in Planet-Hosting Binary Stars. I. General Theory

Giving NASA’s SciX A Quick Astrobiology Roadtest

An Ultraviolet Instrument On The Habitable Worlds Observatory: Considerations and Capability Trades On The Multi-Object, Integral-field, and High-resolution Modes Of A Potential UVI

The Hydrological Cycle and Circulation of Tidally-Locked Planets with A Finite Moisture Inventory

Fermentation Heterotrophy Can Reproduce Enceladus’s H2 And CH4 Under Limited Serpentinization

Perseverance Mars Rover Sets Off-World Record for Total Distance Driven