Exoplanets – worlds of other suns

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A compact multi-planet system transiting HIP 29442 (TOI-469) discovered by TESS and ESPRESSO. Radial velocities lead to the detection of transits with low signal-to-noise ratio
https://arxiv.org/abs/2308.13310

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New giant planet shows evidence of possible planetary collisions
https://phys.org/news/2023-08-giant-pla ... sions.html
by University of Bristol

A Neptune-sized planet denser than steel has been discovered by an international team of astronomers, who believe its composition could be the result of a giant planetary clash.

TOI-1853b's mass is almost twice that of any other similar-sized planet known and its density is incredibly high, meaning that it is made up of a larger fraction of rock than would typically be expected at that scale.

In the study, published August 30 in Nature, scientists led by Luca Naponiello of University of Rome Tor Vergata and the University of Bristol suggest that this is the result of planetary collisions. These huge impacts would have removed some of the lighter atmosphere and water leaving a multitude of rock behind.

Senior Research Associate and co author Dr. Phil Carter from Bristol's School of Physics, explained, "We have strong evidence for highly energetic collisions between planetary bodies in our solar system, such as the existence of Earth's moon, and good evidence from a small number of exoplanets.

"We know that there is a huge diversity of planets in exoplanetary systems; many have no analog in our solar system but often have masses and compositions between that of the rocky planets and Neptune/Uranus (the ice giants).

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Scientists detect and validate the longest-period exoplanets found with TESS
https://phys.org/news/2023-08-scientist ... -tess.html
by University of New Mexico

Scientists from The University of New Mexico (UNM), and Massachusetts Institute of Technology (MIT) have detected and validated two of the longest-period exoplanets found by TESS to date. These long period large exoplanets orbit a K dwarf star and belong to a class of planets known as warm Jupiters, which have orbital periods of 10–200 days and are at least six times Earth's radius. This recent discovery offers exciting research opportunities for the future of finding long-period planets that resemble those in our own solar system.

The research titled "TOI-4600 b and c: Two long-period giant planets orbiting an early K dwarf" will be published in a future issue of The Astrophysical Journal Letters. The exoplanets, TOI-4600 b and c, were detected using photometric data from the Transiting Exoplanet Survey Satellite (TESS) and followed up with observations using the telescopes on the ground since they provide better resolution.

The observing strategy adopted by NASA's TESS, which divides each hemisphere into 13 sectors that are surveyed for roughly 28 days, is producing the most comprehensive all-sky search for transiting planets. This approach has already proven its capability to detect both large and small planets around different kinds of stars. In the case of TOI-4600, the star is a K dwarf star, also known as an orange dwarf, which are stars slightly smaller and cooler than the sun.

https://phys.org/news/2023-08-scientist ... -tess.html

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Here is another article on that same topic:

Latest Look at TRAPPIST-1 Planet Raises Concerns of Star 'Contamination'
by Michele Star
September 28, 2023
Introduction:

(Science Alert) Earlier this year, the James Webb Space Telescope dashed hopes for life on one of the most Earth-like exoplanets discovered in the Milky Way.

TRAPPIST-1b, a world 1.4 times the mass and 1.1 times the radius of Earth, just 40 light-years away, has no detectable atmosphere to protect it from the scorching radiation of its host star.

That finding, made using mid-infrared photometric observations, wasn't an unexpected one, however; the research was more about making a close study of a smaller, rocky world at cooler temperatures than we usually do.

Now, new JWST near-infrared spectroscopic observations are in – and they suggest that the behavior of the exoplanet's host star may be interfering with our ability to make accurate measurements of that exoplanet.

TRAPPIST-1b is still uninhabitable to life as we know it, mind you. But the discovery, led by astronomer Olivia Lim of the University of Montreal, suggests that stellar contamination could produce false detections of molecules that aren't related to the exoplanet.

Read more here: https://www.sciencealert.com/latest-lo ... ination

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Not So Fast Kepler-1513: A Perturbing Planetary Interloper in the Exomoon Corridor
https://arxiv.org/list/astro-ph.EP/new