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  • Simulated Impact on LSST Data of Starlink V1.5 and V2 Satellites
    The new Starlink V2 satellites incorporate improvements to the chassis brightness through dielectric mirrors, off-pointing solar arrays, and blackened exposed components. For the general case in which the reflectivities are initially unknown, we simulate Legacy Survey of Space and Time (LSST) operations and repeated photometry of every satellite in simulated model constellations. We derive a brightness model of the Starlink V2 satellite and study the simulated apparent brightness as a function of the satellite position relative to the observer and the Sun. Simulated V2 Starlink satellites appear brightest at two distinct positions in the sky: toward the Sun at low elevations where light is specularly reflected, and nearly overhead where the satellite is closest to the observer. A simulation of Starlink V2 satellites at 550 km height distributed across a series of Walker constellations with varying inclinations was analyzed to study the impact on LSST observations. For every thousand V2 Starlink satellites observed, we find only 0.93 will appear brighter than 7th magnitude. The off-pointed solar array and reduced diffuse reflection of the chassis mitigate the brightness. Finally, we simulate lowering this Walker constellation to 350 km. Only 0.56 V2 Starlink satellites per thousand brighter than 7 AB magnitude will be observed in the first hour at this height. This is a 40% reduction in number of bright satellites entering the focal plane compared to the constellation at 550 km height. We find that a combination of factors yield an apparent surface brightness of these satellites for LSST operations only 5% brighter than at 550 km orbit.

  • TESS Investigation—Demographics of Young Exoplanets (TI-DYE). IV. A Jovian-radius Planet Orbiting a 34 Myr Sun-like Star in the Vela Association
    The discovery of infant (<50 Myr), close-in (<30-day-period) planets is vital in understanding the formation mechanisms that lead to the distribution of mature transiting planets as discovered by Kepler. Despite several discoveries in this age bin, the sample is still too small for a robust statistical comparison to older planets. Here we report the validation of TOI-6448b, an 8.8 ± 0.8 R⊕ planet on a 14.8-day orbit. TOI-6448 was previously identified to be a likely member of Vela Population IV. We confirm the star’s membership and rederive the age of the cluster using isochrones, variability, and gyrochronology. We find the star, and thus planet, to be 34 ± 3 Myr. Like other young planets, TOI-6448 b lands in a region of parameter space with few older planets. While just one data point, this fits with prior findings of an excess of 5–11 R⊕ planets around young stars far beyond what can be explained by reduced sensitivity at young ages. Our ongoing searches of Vela, Taurus-Auriga, Sco-Cen, and Orion are expected to reveal dozens more <50 Myr transiting planets.

  • Discovery of 178 Open Clusters with Gaia DR3
    We present 178 new open cluster candidates identified through the application of the HDBSCAN clustering algorithm to astrometric data from the Gaia DR3 catalog. The analysis was performed over 5770 1 deg2 fields centered on OB stars, which serve as tracers of Galactic spiral arms. Using the membership probabilities provided by HDBSCAN, we derived the mean proper motions, parallaxes, and fundamental parameters for each cluster. For a subset of 84 clusters, mean radial velocities were also determined using Gaia data. The cluster parameters (distances, ages, extinctions, and metallicities) were estimated through our nonsubjective multidimensional global optimization code, which fits theoretical isochrones to Gaia photometric data. The quality of the results and their uncertainty support the reality of the clusters, which span distances from 739 to 12,000 pc. Age estimates indicate that 59 clusters are younger than 50 Myr, 20 have intermediate ages, and 99 are classified as old clusters. These results highlight that there is still work to be done on open cluster discovery and reinforce the importance of regular updates to open cluster catalogs.

  • The Gaia–Kepler–TESS-host Stellar Properties Catalog: Uniform Physical Parameters for 10022 Host Stars and 10189 Planets
    We present the first homogeneous catalog of Kepler, K2, and TESS host stars and the corresponding catalog of exoplanet properties, which contain 10022 stars and 10189 planets, respectively. We used isochrone fitting and Gaia DR3 photometry, parallaxes, and spectroscopic metallicities to compute precise, homogeneous Teff, , masses, radii, mean stellar densities, luminosities, ages, distances, and V-band extinctions for 3387, 618, 6017 Kepler, K2, and TESS host stars, respectively. We compared our stellar properties to studies using fundamental and precise constraints, such as interferometry and asteroseismology, and find residual scatters of 2.8%, 5.6%, 5.0%, and 31%, with offsets of 0.2%, 1.0%, 1.2%, and 0.7% between our Teff, radii, masses, and ages and those in the literature, respectively. In addition, we compute planet radii, semimajor axes, and incident fluxes for as many as 4285, 678, and 5226 Kepler, K2, and TESS planets, respectively, and find that the exoplanet radius gap is less prominent in the K2, TESS, and combined samples than in the Kepler sample alone. We suspect this difference is due to heterogeneous planet-to-star radius ratios, shorter time baselines of K2 and TESS, smaller sample sizes, and the different gap locations hinted at by the K2 (∼1.5 R⊕) and TESS (∼1.8 R⊕) planet radius distributions. Finally, we identify a clear radius inflation trend in thousands of hot Jupiters and find 151 hot sub-Neptunian desert planets, in addition to a population of 233 young (≲1 Gyr) host stars as potential opportunities for testing theories of planet formation and evolution.

  • On the Exoplanet Yield of Gaia Astrometry
    We reexamine 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. Our analysis combines a semianalytic model that clarifies key scaling relations with more realistic Monte Carlo simulations. We predict 7500 ± 2100 planet discoveries in the 5 yr dataset (Data Release 4 (DR4)) and 120,000 ± 22,000 over the full 10 yr mission (Data Release 5 (DR5)), with the dominant error arising from uncertainties in giant-planet occurrence. We evaluate the sensitivity of these forecasts to the detection threshold and the desired precision for measurements of planet masses and orbital parameters. Roughly 1900 ± 540 planets in DR4 and 38,000 ± 7300 planets in DR5 should have masses and orbital periods determined to better than 20%. Most detections will be super-Jupiters (3–13 MJ) on 2–5 au orbits around GKM-type stars (0.4–1.3 M⊙) within 500 pc. Unresolved binary stars will lead to spurious planet detections, but we estimate that genuine planets will outnumber them by a factor of 5 or more. An exception is planets around M dwarfs with a < 1 au, for which the false-positive rate is expected to be about 50%. To support community preparation for upcoming data releases, we provide mock catalogs of Gaia exoplanets and planet-impostor binaries.1