Astrogeology, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Status Report

First Comparative Exoplanetology Within a Transiting Multi-planet System: Comparing the atmospheres of V1298 Tau b and c

by Keith CowingJuly 25, 2024July 25, 2024

Comparing the retrieved atmospheric metallicity of V1298 Tau b and c with those of mature exoplanets, with the solar system planets and with young directly imaged planets orbiting HR 8799 (30Myr old). The left panel shows these planets in the metallicity-orbital distance plane and in the right panel we compare the mass-metallicity of these planets. The atmospheric metallicity of the V1298 Tau planets have been derived from the ATMO retrievals (Table 2). The stars show metallicities for retrievals performed using 10M‘ for both planets and the squares for retrievals using 23 and 50M‘ for planet b and c respectively. The metallicities of the HR 8799 system (blue circles) have been obtained from Nasedkin et al. (2024). The grey points show metallicity constraints from pre-JWST observations (mostly driven by HST) taken from Wakeford & Dalba (2020) and the magenta points show metallicities derived from JWST observations. Table I.1 shows the data for the planets shown in magenta with corresponding references. For planets which appear both in the sample of Wakeford & Dalba (2020) and Table I.1, we plot the latter. A comparison between the measured metallicties between he V1298 Tau and HR8799 systems show that these planets have very different atmospheric metal enrichment, indicative of differences in their formation mechanism, disk properties, and location. The red dashed line in the right panel shows a mass-metallicity relation derived in Thorngren & Fortney (2019). The V1298 Tau planets have metal-poor atmospheres by an order of magnitude compared to their mature counterparts and observed mass-metallicity trend among exoplanets. -- astro-ph.EP

The V1298 Tau system (20-30Myr), is a benchmark young multi-planet system that provides the opportunity to perform comparative exoplanetology between planets orbiting the same star right after their formation.

We present the first atmospheric comparison between two planets in the same transiting system: V1298 Tau b and V1298 Tau c. We derive constraints on the mass of planet b and c (<20M_⊕ at 3σ confidence level and 17+13⁻⁶M_⊕ respectively) and atmospheric metallicity (logZ/Z_⊙=-2.040.69−0.59, -0.161.15−0.94 respectively) from atmospheric retrievals.

The V1298 Tau planets, are likely to be similar in terms of mass at the current age, implying that both planets are potential sub-Neptune/super-Earth progenitors. However, planet c is expected to lose a higher fraction of its mass compared to planet b given its close proximity to the host star.

Alternatively, the observed spectrum of planet c can be explained by atmospheric hazes, which is in contrast to planet b where efficient haze formation can be ruled out. Higher haze formation efficiency in planet c could be due to differences in atmospheric composition, temperature and higher UV flux incident compared to planet b.

Saugata Barat, Jean-Michel Désert, Jayesh M. Goyal, Allona Vazan, Yui Kawashima, Jonathan J. Fortney, Jacob L. Bean, Michael R. Line, Vatsal Panwar, Bob Jacobs, Hinna Shivkumar, James Sikora, Robin Baeyens, Antonija Oklopcić, Trevor J. David, John H. Livingston

Comments: Submitted to Astronomy ad Astrophysics
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2407.14995 [astro-ph.EP] (or arXiv:2407.14995v1 [astro-ph.EP] for this version)
Submission history
From: Saugata Barat
[v1] Sat, 20 Jul 2024 22:06:06 UTC (12,061 KB)
https://arxiv.org/abs/2407.14995
Astrobiology,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp... More by Keith Cowing