Imaging Low-mass Planets Within The Habitable Zone Of α Centauri


Simulated planet brightness and basic properties of the α Centauri system. a N-band (10–12.5 μm) contrast vs. angular separation of planets around α Centauri A (blue) and B (green), assuming face-on circular orbits, a Bond albedo of 0.3 and internal heating that provides an additional 10% of the planets’ equilibrium temperatures. The curves correspond from bottom to top to planetary radii equivalent to that of Earth, a Super-Earth (1.7×Earth’s radius, R⊕), Neptune, and Jupiter. The blue and green shaded regions show the location of the classical habitable zones around α Centauri A and B, respectively (13). b Diagram of the orbital properties and approximate habitable zones of the α Centauri AB system. Note that this diagram does not show the 79º inclination of the orbit as seen from Earth, or the tertiary dwarf star, Proxima Centauri, at ~104 au.

Giant exoplanets on wide orbits have been directly imaged around young stars. If the thermal background in the mid-infrared can be mitigated, then exoplanets with lower masses can also be imaged.

Here we present a ground-based mid-infrared observing approach that enables imaging low-mass temperate exoplanets around nearby stars, and in particular within the closest stellar system, alpha Centauri. Based on 75-80% of the best quality images from 100 hours of cumulative observations, we demonstrate sensitivity to warm sub-Neptune-sized planets throughout much of the habitable zone of alpha Centauri A.

This is an order of magnitude more sensitive than state-of-the-art exoplanet imaging mass detection limits. We also discuss a possible exoplanet or exozodiacal disk detection around alpha Centauri A. However, an instrumental artifact of unknown origin cannot be ruled out. These results demonstrate the feasibility of imaging rocky habitable-zone exoplanets with current and upcoming telescopes.

K. Wagner, A. Boehle, P. Pathak, M. Kasper, R. Arsenault, G. Jakob, U. Kaufl, S. Leveratto, A.-L. Maire, E. Pantin, R. Siebenmorgen, G. Zins, O. Absil, N. Ageorges, D. Apai, A. Carlotti, É. Choquet, C. Delacroix, K. Dohlen, P. Duhoux, P. Forsberg, E. Fuenteseca, S. Gutruf, O. Guyon, E. Huby, D. Kampf, M. Karlsson, P. Kervella, J.-P. Kirchbauer, P. Klupar, J. Kolb, D. Mawet, M. N'Diaye, G. Orban de Xivry, S. P. Quanz, A. Reutlinger, G. Ruane, M. Riquelme, C. Soenke, M. Sterzik, A. Vigan, T. de Zeeuw

Comments: 29 pages, 11 figures, published in Nature Communications
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2102.05159 [astro-ph.EP] (or arXiv:2102.05159v1 [astro-ph.EP] for this version)
Submission history
From: Kevin Wagner
[v1] Tue, 9 Feb 2021 22:32:58 UTC (7,925 KB)
https://arxiv.org/abs/2102.05159
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