The ESO SupJup Survey IV. Unveiling the carbon isotope ratio of GQ Lup B and its host star
| Autor: | Picos, D. González, Snellen, I. A. G., de Regt, S., Landman, R., Zhang, Y., Gandhi, S., Sánchez-López, A. |
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| Rok vydání: | 2025 |
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| Druh dokumentu: | Working Paper |
| DOI: | 10.1051/0004-6361/202451936 |
| Popis: | The carbon isotope ratio ($^{12}\mathrm{C}/^{13}\mathrm{C}$) is a potential tracer of giant planet and brown dwarf formation. The GQ Lup system, hosting the K7 T Tauri star GQ Lup A and its substellar companion GQ Lup B, offers a unique opportunity to investigate this ratio in a young system. We aim to characterise the atmosphere of GQ Lup B, determining its temperature, chemical composition, spin, surface gravity, and $^{12}\mathrm{C}/^{13}\mathrm{C}$, while also measuring the same ratio for its host star, GQ Lup A. High-resolution K-band spectra of GQ Lup were obtained using CRIRES+ at the VLT. We modelled the starlight contribution from GQ Lup A and fitted GQ Lup B\'s spectrum with atmospheric models from petitRADTRANS. The $^{12}\mathrm{C}/^{13}\mathrm{C}$ ratio for GQ Lup A was derived using isotope-sensitive PHOENIX models. Atmospheric analysis of GQ Lup B revealed abundances of H$_2$O, $^{12}$CO, $^{13}$CO, HF, Na, Ca, and Ti, along with a C/O ratio of $0.50 \pm 0.01$, consistent with the solar value. The carbon isotope ratio was measured as $^{12}\mathrm{C}/^{13}\mathrm{C} = 53^{+7}_{-6}$ for GQ Lup B and $^{12}\mathrm{C}/^{13}\mathrm{C} = 51^{+10}_{-8}$ for GQ Lup A. Strong veiling of the photospheric lines of GQ Lup A was identified and accounted for. The similar $^{12}\mathrm{C}/^{13}\mathrm{C}$ values in GQ Lup A and B suggest a common origin from a shared material reservoir, supporting formation via disc fragmentation or gravitational collapse. Comment: Accepted for publication in A&A, 20 pages, 14 figures |
| Databáze: | arXiv |
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