Issue |
A&A
Volume 678, October 2023
|
|
---|---|---|
Article Number | A121 | |
Number of page(s) | 18 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361/202346109 | |
Published online | 13 October 2023 |
How much large dust could be present in hot exozodiacal dust systems?
1
Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel,
Leibnizstr. 15,
24118
Kiel, Germany
e-mail: tstuber@astrophysik.uni-kiel.de
2
Sterrenkundig Observatorium, Ghent University,
Krijgslaan 281-S9,
9000
Gent, Belgium
3
Astrophysikalisches Institut und Universitätssternwarte, Friedrich-Schiller-Universität Jena,
Schillergässchen 2–3,
07745
Jena, Germany
4
Department of Astronomy and Steward Observatory, The University of Arizona,
933 North Cherry Ave,
Tucson, AZ
85721, USA
5
Large Binocular Telescope Observatory, The University of Arizona,
933 North Cherry Ave,
Tucson, AZ
85721, USA
Received:
9
February
2023
Accepted:
19
July
2023
Context. An infrared excess over the stellar photospheric emission of main-sequence stars has been found in interferometric surveys, commonly attributed to the presence of hot exozodiacal dust (HEZD). While submicrometer-sized grains in close vicinity to their host star have been inferred to be responsible for the found near-infrared excesses, the presence and amount of larger grains as part of the dust distributions are weakly constrained.
Aims. We quantify how many larger grains (above-micrometer-sized) could be present in addition to submicrometer-sized grains, while being consistent with observational constraints. This is important in order to distinguish between various scenarios for the origin of HEZD and to better estimate its observational appearance when observed with future instruments.
Methods. We extended a model suitable to reproduce current observations of HEZD to investigate a bimodal size distribution. By deriving the characteristics of dust distributions whose observables are consistent with observational limits from interferometric measurements in the K and N bands we constrained the radii of sub- and above-micrometer-sized grains as well as their mass, number, and flux density ratios.
Results. In the most extreme cases of some of the investigated systems, large grains ≳10 µm might dominate the mass budget of HEZD while contributing up to 25 % of the total flux density originating from the dust at a wavelength of 2.13 µm and up to 50 % at a wavelength of 4.1 µm; at a wavelength of 11.1 µm their emission might clearly dominate over the emission of small grains. While it is not possible to detect such hot-dust distributions using ALMA, the ngVLA might allow us to detect HEZD at millimeter wavelengths.
Conclusions. Large dust grains (above-micrometer-sized) might have a more important impact on the observational appearance of HEZD than previously assumed, especially at longer wavelengths.
Key words: circumstellar matter / interplanetary medium / infrared: planetary systems / submillimeter: planetary systems / methods: numerical
© The Authors 2023
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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