The carbon isotope ratio of

Springer Link (Chiba Institute of Technology)

Abstract

Isotopic ratios trace the formation and evolution of planets and link their atmospheres to the chemistry of their natal protoplanetary discs. We measure 12C/13C = 58−15+18 in the atmosphere of the young super-Jupiter β Pic b from 11 nights of CRIRES+ K-band spectroscopy (ℜ ≈ 100 000) at the Very Large Telescope (VLT). We detect both 12CO and 13CO and constrain 12C/13C with a Bayesian retrieval jointly fitted with near-infrared photometry. The inferred 12C/13C is consistent with the present-day interstellar medium (ISM), is below the solar value, and is comparable to measurements in other young super-Jupiters. We also retrieve Teff = 1629−28+30 K, near-solar to mildly super-solar metallicity ([M/H] = 0.20−012+0.16), a solar-like carbon-to-oxygen ratio (C/O = 0.52 ± 0.03), and tentative evidence for thick clouds. We analyse each night independently and combine the results of the six epochs with the highest signal-to-noise ratio (S/N), propagating night-to-night scatter into the final uncertainties. This provides an isotopic benchmark for a directly-imaged planet interior to the CO snow line.

Authors 9

1. D. González Picos Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory , Leiden University , PO Box 9513 , 2300 RA Leiden , The Netherlands

2. Ignas A. G. Snellen Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory , Leiden University , PO Box 9513 , 2300 RA Leiden , The Netherlands

3. R. Landman Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory , Leiden University , PO Box 9513 , 2300 RA Leiden , The Netherlands

4. S. de Regt Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory , Leiden University , PO Box 9513 , 2300 RA Leiden , The Netherlands

5. Natalie Grasser Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory , Leiden University , PO Box 9513 , 2300 RA Leiden , The Netherlands

6. Jayne Birkby

   University of Oxford

   Affiliation as printed

   Astrophysics , University of Oxford , Denys Wilkinson Building , Keble Road , Oxford OX1 3RH , UK

7. T. Stolker Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory , Leiden University , PO Box 9513 , 2300 RA Leiden , The Netherlands

8. Ioannis Koutalios Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory , Leiden University , PO Box 9513 , 2300 RA Leiden , The Netherlands

9. Matthew A. Kenworthy Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory , Leiden University , PO Box 9513 , 2300 RA Leiden , The Netherlands