KOBE Experiment: Korean dwarfs orbiting habitable exoplanets. Project objectives, target selection, and star characterization

Extrasolar planets have been discovered within the habitable zone of different star types. The symbol symbol is displayed in the legend and its size measures with planet radius for circle symbols and planet mass for squares and triangle symbols. Green areas show the optimistic and conservative habitable zones from Kopparapu et al. (2013) Climate Models. The kernel density estimation (KDE) on the right panel shows the distribution of planetesimals within Hz. The symbols and the black line correspond to the occurrence rates of HZ planets for different star types obtained by correlating the occurrence rates of Kunimoto & Matthews (2020) with the space of the HZ parameter. The two horizontal dotted lines include the late K-dwarf system. The difference between the observed intensity profile and the expected event clearly demonstrates the nature of the observed bias for this desert due to the lack of focus on this system.


The discovery of habitable worlds is one of humanity’s greatest endeavors. So far, astrobiological studies show that liquid water is one of the most important components for the evolution of life. Its chemical properties and ability to dissolve and thus impart other substances make this component an essential part of the evolution of life.

As a result, the search for life as we know it is directly related to the search for liquid water. For remote detection of life in distant planetary systems, this means searching for planets in the so-called habitable zone. In that sense, K-dwarf stars are the perfect hosts. Unlike G-dwarfs, the habitable zone is closer, which makes detecting the planet easier using transit or radial velocity techniques. In contrast to M-dwarfs, stellar activity is much smaller, and therefore has less impact on both the detectability and true habitability of the planet.

Also, K-dwarfs are the quietest in terms of oscillations and granulation noise. Despite this, there is a dearth of planets in the habitable zone of K-dwarfs due to the lack of monitoring programs dedicated to this space parameter. In response to a call for the Calar Alto Observatory Heritage Programs, we began the first dedicated, systematic search for habitable planets around Korean dwarfs, and Korean dwarfs orbiting exoplanets (KOBE).

This survey monitors the radial velocity of 50 carefully selected K dwarfs using the CARMENES instrument over 5 semesters with an average of 90 data points per target. Based on planet occurrence rates associated with our detection limits, we would expect to find 1.68 ± 0.25 planets per star in the KOBE sample and in half of the sample we would expect to find one of those within the habitable zone. In this paper, we describe project motivation, objectives, goal selection, and initial stellar characterization.

Lillo-Box J, Santos NC, Silva AM, Barrado D, Faria J, Castro-Gonzalez A, Balsalobre-Ruza O, Morales-Calderon M, Saavedra-A, Ivory E, Sousa SG, Adibekyan V, Berihuete A, Barros SCC , Delgado-Mena E, Huelamo N, Deleuil M, Demangeon ODS, Figueira P, Grouffal S, Olive J, Azzaro M, Bergond G, A. Fernandez-Martin, D. Galadi, E. Gallego, A. Gardini, S. Gongora, A. Guijarro, I. Hermelo, P. Martin, P. Minguez, L.M. Montoya, S. Pedraz, J. I. Vico Linares

Comments: Accepted for publication in A&A. 12 pages, 9 figures, 1 table
Topics: Earth and Planetary Astrophysics (astro-ph.EP); Solar and stellar astrophysics (astro-ph.SR)
Cited as follows: arXiv: 2209.05205 [astro-ph.EP] (or arXiv: 2209.05205v1 [astro-ph.EP] for this version)
Submission date
WHO: Jorge Lillo Box
[v1] Monday, September 12, 2022, 12:39:03 PM UTC (2,998 KB)
Whole sheet: https://arxiv.org/abs/2209.05205