THE EFFECTS OF SNOWLINES ON C/O IN PLANETARY ATMOSPHERES

By K. Oberg, R. Murray-Clay, E. Bergin. 2011

482 citations recorded by the source corpus.

The C/O ratio is predicted to regulate the atmospheric chemistry in hot Jupiters. Recent observations suggest that some exoplanets, e.g., Wasp 12-b, have atmospheric C/O ratios substantially different from the solar value of 0.54. In this Letter, we present a mechanism that can produce such atmospheric deviations from the stellar C/O ratio. In protoplanetary disks, different snowlines of oxygen- and carbon-rich ices, especially water and carbon monoxide, will result in systematic variations in the C/O ratio both in the gas and in the condensed phases. In particular, between the H2O and CO snowlines most oxygen is present in icy grains—the building blocks of planetary cores in the core accretion model—while most carbon remains in the gas phase. This region is coincidental with the giant-planet-forming zone for a range of observed protoplanetary disks. Based on standard core accretion models of planet formation, gas giants that sweep up most of their atmospheres from disk gas outside of the water snowline will have a C/O ∼ 1, while atmospheres significantly contaminated by evaporating planetesimals will have a stellar or substellar C/O when formed at the same disk radius. The overall metallicity will also depend on the atmosphere formation mechanism, and exoplanetary atmospheric compositions may therefore provide constraints on where and how a specific planet formed.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/9155b5660aaa323a911a4b9209c9627af598a34b

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. N. Madhusudhan
2. Jon Fortney
3. A. Showman
4. M. Line
5. Sara Seager
6. D. Deming
7. T. Birnstiel
8. H. Knutson

In Instrumentation

1. N. Madhusudhan
2. Jon Fortney
3. M. Line
4. A. Showman
5. H. Knutson
6. D. Charbonneau
7. D. Deming
8. J. D'esert

Citations in the corpus

• A SYSTEMATIC RETRIEVAL ANALYSIS OF SECONDARY ECLIPSE SPECTRA. II. A UNIFORM ANALYSIS OF NINE PLANETS AND THEIR C TO O RATIOS (2013, background): “Öberg et al. (2011) have suggested that gas giant planets could form with different C to O ratios depending on their location in the protoplanetary disk, suggesting that C to O ratios for hot Jupiters could provide constraints on their formation locations.”
• MAKE SUPER-EARTHS, NOT JUPITERS: ACCRETING NEBULAR GAS ONTO SOLID CORES AT 0.1 AU AND BEYOND (2014, background): “Furthermore, the disk’s solid surface density is enhanced outside the “ice line” (water condensation front) at ∼2–3 AU (Lecar et al. 2006; see also Öberg et al. 2011).”
• THE MASS–METALLICITY RELATION FOR GIANT PLANETS (2015, background): “The gas need not share the exact composition of the parent star, due to condensation and migration of solids within the disk (Lodders 2009; Öberg et al. 2011).”
• A PRECISE WATER ABUNDANCE MEASUREMENT FOR THE HOT JUPITER WASP-43b (2014, background): “…can therefore help constrain the disk chemistry, location, and surface density of solids where it formed (e.g. Lodders 2004; Mousis et al. 2009; Öberg et al. 2011; Madhusudhan et al. 2011; Mousis E-mail: laura.kreidberg@uchicago.edu 1 Department of Astronomy and Astrophysics, University of…”
• C/O RATIO AS A DIMENSION FOR CHARACTERIZING EXOPLANETARY ATMOSPHERES (2012, background): “Equally drastic are the protoplanetary conditions required to form CRPs, such as a naturally carbon-rich gas in the disk (Oberg et al. 2011), or a sink of oxygen in the disk (Madhusudhan et al. 2011b), or the predominance of planetesimals rich in carbonaceous material like tar, instead of water-ice…”
• HD 209458b in new light: evidence of nitrogen chemistry, patchy clouds and sub-solar water (2017, background): “Such constraints are just beginning to provide tantalising clues to planetary formation and migration pathways (e.g. Öberg et al. 2011; Madhusudhan et al. 2014c; Mordasini et al. 2016).”
• Exoplanetary Atmospheres: Key Insights, Challenges, and Prospects (2019, methodology): “H2O, CO, CO2) were adopted based on observations of protoplanetary environments and the interstellar medium, or on theoretical models (197, 190, 164).”
• A DETECTION OF WATER IN THE TRANSMISSION SPECTRUM OF THE HOT JUPITER WASP-12b AND IMPLICATIONS FOR ITS ATMOSPHERIC COMPOSITION (2015, background): “…formation site, the relative accretion rates of gas and solids, and possible migration pathways (e.g. Atreya et al. 1999; Owen et al. 1999; Gautier et al. 2001; Atreya et al. 2003; Hersant et al. 2004; Lodders 2004; DodsonRobinson et al. 2009; Öberg et al. 2011; Madhusudhan et al. 2011a, 2014a).”
• Volatile carbon locking and release in protoplanetary disks. A study of TW Hya and HD 100546 (2016, background): “A-9027. the freeze out of CO and other carrier molecules (Öberg et al. 2011); the transformation of this icy reservoir into complex organic molecules in cold regions (van Dishoeck 2008; Walsh et al. 2014b); and the vertical transport and oxidation of carbonaceous solids in warm gas (Lee et al.…”
• SIMULTANEOUS DETECTION OF WATER, METHANE, AND CARBON MONOXIDE IN THE ATMOSPHERE OF EXOPLANET HR 8799 b (2015, methodology): “On the other hand, if giant planets form primarily by the multi-step coreaccretion (CA) process, a range of element abundances are possible (Öberg et al. 2011).”
• EVIDENCE OF FAST PEBBLE GROWTH NEAR CONDENSATION FRONTS IN THE HL TAU PROTOPLANETARY DISK (2015, background): “Because volatility is highly species specific, it is the condensation fronts of the principal solid-vapor reservoirs in the mid-plane of protoplanetary disks that set the rough boundaries of planetesimals with different compositions (Öberg et al. 2011).”
• CHARACTERIZING TRANSITING EXOPLANET ATMOSPHERES WITH JWST (2015, background): “E P] 1 7 N 2 et al. 2011) which can potentially help diagnose where a planet formed relative to the H2O and CO ice lines in its protoplanetary disk (Öberg et al. 2011).”
• Detection of water absorption in the day side atmosphere of HD 189733 b using ground-based high-resolution spectroscopy at 3.2 μm (2013, background): “…to provide constraints on the relative abundances of these molecules in planetary atmospheres, and hence an estimate of the carbon-to-oxygen ratio (C/O), which is thought to have strong implications for the formation and migration history of the planets (see e.g. Lodders 2004; Öberg et al. 2011).”
• H2O abundances and cloud properties in ten hot giant exoplanets (2018, background): “…estimates of individual objects as well as populations with the derived statistical uncertainties would be valuable inputs for studies investigating planet formation and migration (Öberg et al. 2011; Mousis et al. 2012; Madhusudhan et al. 2014b; Mordasini et al. 2016; Madhusudhan et al. 2017).”
• Chemical enrichment of giant planets and discs due to pebble drift (2017, methodology): “With the robust detection of molecular species such as H2O, CH4, CO, and CO2 becoming possible in the atmospheres of hot Jupiters, the idea of testing planet formation using planet composition is very appealing (Lodders & Fegley 2002; Madhusudhan 2012; Moses et al. 2013; Tsai et al. 2016).”
• 2018 Census of Interstellar, Circumstellar, Extragalactic, Protoplanetary Disk, and Exoplanetary Molecules (2018, background): “…crucial roles in a wide range of applications, from broadening our understanding of interstellar chemical evolution (Herbst & van Dishoeck 2009) and the formation of planets (Öberg et al. 2011) to providing exceptional astrophysical probes of physical conditions and processes (Friesen et al. 2013).”
• Global Simulations of the Inner Regions of Protoplanetary Disks with Comprehensive Disk Microphysics (2017, background): “Furthermore, astrochemistry has emerged to provide more refined information about the physical environments of PPDs with implications for planetary composition (e.g., Öberg et al. 2011; Henning & Semenov 2013; Qi et al. 2013; Cleeves et al. 2016).”