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Six planets found by nearby star

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International astronomers have discovered a half-dozen planets orbiting one of our nearby bright stars. The star, called HD 110067 lives in the Coma Berenices constellation, and is around 100 light-years away from us. The planets are referred to as 'sub-Neptunes' which classifies their size as bigger than Earth, smaller than Neptune. The team says the innermost planet has an orbit that takes nine (Earth) days to complete, and the outermost takes 54. It's likely that the planets have hydrogen-rich atmospheres, they add, with the planets remaining practically unchanged for the last four billion years.

Journal/conference: Nature

Research: Paper

Organisation/s: University of Chicago, USA

Funder: For full funding information see the paper

Media release

From: Springer Nature

The discovery of six exoplanets orbiting around a nearby bright star, HD 110067 in the Coma Berenices constellation, is reported in Nature this week. The planets have radii between that of Earth and Neptune. Details of their orbits are calculated, along with estimates of their masses and densities, which offer clues about the formation of the system and compositions of the planets’ atmospheres.

Planets with radii between that of the Earth and Neptune (referred to as ‘sub-Neptunes’) are found in close-in orbits around more than half of all Sun-like stars, but details of their composition, formation and evolution are not well understood. HD 110067 is a bright star in the Coma Berenices constellation (around 100 light-years away), which is visible from Earth’s Northern Hemisphere.

Observations of HD 110067 made by NASA’s Transiting Exoplanet Survey Satellite (TESS) in 2020 and 2022 revealed several dips in the star’s brightness, and with additional observations from the ‘CHaracterising ExOPlanets Satellite’ (CHEOPS) the signals were interpreted as six planets passing in front of the star, report Rafael Luque and colleagues. By studying the three innermost planets, the authors calculated the orbits of all six planets, ranging from around 9 days for the innermost planet to around 54 days for the outermost planet. The authors calculate the masses of the planets and estimate the densities, which are relatively low; the authors suggest that the low densities could be explained by large, hydrogen-rich atmospheres. All six planets are in resonant orbits, in which the planets exert regular forces on each other as they orbit. This feature suggests that the system remains practically unchanged since its birth, at least four billion years ago.

HD 110067 is the brightest star found to host more than four transiting exoplanets to date, the authors note, and add that more planets may exist within or beyond the temperate zone, although such observations have not been made so far. They conclude that the HD 110067 system offers a chance to learn more about sub-Neptunes and how systems in this configuration might form.

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Multimedia:

  • Video 1

    To-scale animation of the orbits of the six resonant planets in the HD110067 system. The pitch of the notes played when each planet transits matches the resonant change in orbital frequencies between each subsequent planet. Annotations describe the discovery process of each planet in turn. The background image is the TESS field centred on HD 110067 from which the first hints of exoplanets orbiting the star were first seen (Credit: NASA/MIT/TESS and Ethan Kruse). The relative sizes of the planets (as shown by the key to the right) is accurate, although their true size compared to the star is much smaller.

    Attribution: Animation, composition and annotations by Dr. Hugh Osborn (University of Bern)

    Permission Category: © - Only use with this story

    Last Modified: 28 Nov 2023 11:26am

    Note: High resolution video files are only available for download here by registered journalists who are logged in.

  • Video 2

    Animation of the orbits of the six planets around HD110067. The orbits and planetary sizes are to-scale relative to each other (although not relative to the size of the star). The yellow band indicates the transit region where we are able to observe the planets passing in front of HD110067. The pitch of the notes played when each planet transits matches the resonant change in orbital frequencies between each subsequent planet.

    Attribution: Animation & music by Dr. Hugh Osborn (University of Bern)

    Permission Category: © - Only use with this story

    Last Modified: 28 Nov 2023 11:28am

    Note: High resolution video files are only available for download here by registered journalists who are logged in.

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