Probing the structure of protoplanetary disks: a comparative study of DM Tau, LkCa 15, and MWC 480

By V. Pi'etu, A. Dutrey, S. Guilloteau. 2007

254 citations recorded by the source corpus.

Context. The physical structure of proto-planetary disks is not yet well constrained by current observations. Millimeter interferometry is an essential tool to investigate young disks. Aims. We study the vertical and radial temperature distribution in a few well-known disks from an observational perspective. The surface density distribution of CO and HCO + and the scale-height are also investigated. Methods. We report CO observations at sub-arcsecond resolution with the IRAM array of the disks surrounding MWC 480, LkCa 15, and DM Tau, and simultaneous measurements of HCO + J = 1 → 0. To derive the disk properties, we fit a standard disk model in which all parameters are power laws of the distance to the star to the data. Possible biases associated with the method are detailed and explained. We compare the properties of the observed disks with similar objects. Results. We find evidence for a vertical temperature gradient in the disks of MWC 480 and DM Tau, as in AB Aur, but not in LkCa 15. The disk temperatures increase with stellar effective temperature. Except for AB Aur, the bulk of the CO gas is at temperatures smaller than 17 K, below the condensation temperature on grains. We find the scale height of the CO distribution to be larger (by 50%) than the expected hydrostatic scale height. The total amount of CO and the isotopologue ratio depends globally on the star. The more UV luminous objects appear to have more CO, but there is no simple dependency. The [ 13 CO]/[HCO + ] ratio is ∼600, with substantial variations between sources, and with radius. The temperature behavior is consistent with expectations, but published chemical models have difficulty reproducing the observed CO quantities. Changes in the slope of the surface density distribution of CO, compared to the continuum emission, suggest a more complex surface density distribution than is usually assumed in models. Vertical mixing seems an important chemical agent, as does photo-dissociation by the ambient UV radiation at the disk’s outer edge.

Subfields: Astronomy and Astrophysics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/8e147dcaca30285e60b7d713880b3d5b83887087

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In Astronomy and Astrophysics

1. D. Wilner
2. S. Andrews
3. T. Birnstiel
4. A. Hughes
5. C. Dullemond
6. C. Qi
7. Jonathan P. Williams
8. Matthew R. Bate

In Spectroscopy

1. D. Wilner
2. S. Andrews
3. A. Hughes
4. T. Birnstiel
5. C. Qi
6. C. Dullemond
7. Matthew R. Bate
8. E. Bergin

Citations in the corpus

• Gaps, Rings, and Non-Axisymmetric Structures in Protoplanetary Disks - From Simulations to ALMA Observations (2014, background): “It is assumed that the absolute value of this velocity component is on the order of 100 ms−1 (e.g., Dartois et al. 2003; Piétu et al. 2007; Hughes et al. 2011).”
• On the diversity and statistical properties of protostellar discs (2018, background): “…objects where both the gas and dust are observed it is common for the radius of the gas disc to be larger than that of the (sub-)mm dust disc (e.g. Piétu et al. 2007, 2014; Isella et al. 2007; Panić et al. 2009; Andrews et al. 2012; Rosenfeld et al. 2013; de Gregorio-Monsalvo et al. 2013; Walsh…”
• STRUCTURE AND EVOLUTION OF PRE-MAIN-SEQUENCE CIRCUMSTELLAR DISKS (2009, background): “…pre-main sequence circumstellar disks such as LkHα 330 (Brown et al. 2008), HD 163296 (Isella et al. 2007), AB Aur, MWC 480, DM Tau and LkCa 15 (Piétu et al. 2005, 2006, 2007), CQ Tau (Testi et al. 2003), DL Tau, UZ Tau, BP Tau and GM Aur (Simon et al. 2000), TW Hya (Wilner et al. 2000)…”
• PROTOPLANETARY DISK STRUCTURES IN OPHIUCHUS (2009, background): “While these are only qualitative estimates of the uncertainties on γ, they are in reasonable agreement with more statistically robust error estimates for similar studies (e.g., Piétu et al. 2007; Isella et al. 2009).”
• A dual-frequency sub-arcsecond study of proto-planetary disks at mm wavelengths: first evidence for radial variations of the dust properties (2011, methodology): “This is confirmed through CO isotopologue studies in several sources, such as AB Aur (Piétu et al. 2005), DM Tau, LkCa 15, and MWC 480 (Piétu et al. 2007).”
• RESOLVED IMAGES OF LARGE CAVITIES IN PROTOPLANETARY TRANSITION DISKS (2011, methodology): “In most cases, the viewing geometry was fixed based on models of CO spectral images in the literature (Dutrey et al. 1998; Piétu et al. 2007; Isella et al. 2010b; Lyo et al. 2011) or the new J=3−2 data from the SMA (for LkHα 330, UX Tau A, and RX J1615-3255; details will be presented elsewhere).”
• EMPIRICAL CONSTRAINTS ON TURBULENCE IN PROTOPLANETARY ACCRETION DISKS (2010, background): “However, this interpretation is uncertain: it is important to exercise caution when deriving information about velocity fluctuations on scales smaller than the spectral resolution of the data (as noted by, e.g., Piétu et al. 2007).”
• CHEMICAL PROCESSES IN PROTOPLANETARY DISKS (2010, background): “…2006, 2008), DM Tauri (Dutrey et al. 1997; Ceccarelli et al. 2004, 2005; Guilloteau et al. 2006; catherine.walsh@qub.ac.uk Dutrey et al. 2007; Piétu et al. 2007) and LkCa 15 (van Zadelhoff et al. 2001; Aikawa et al. 2003; Qi et al. 2003; Thi et al. 2004; Dutrey et al. 2007; Piétu et al. 2007).”
• THE MASS DEPENDENCE BETWEEN PROTOPLANETARY DISKS AND THEIR STELLAR HOSTS (2013, background): “…(Mdyn) are available for ∼20 sources in this sample, derived either from gas disk rotation curves (Simon et al. 2000; Dutrey et al. 2003, 2008; Piétu et al. 2007; Schaefer et al. 2009; Tang et al. 2012), radial velocity monitoring of spectroscopic binaries (plus some external inclination…”
• Turbulence in the TW Hya Disk (2018, background): “While observational evidence in the sub-mm/mm confirms the presence of a temperature gradient in the outer disk (e.g. Piétu et al. 2007; Panić et al. 2008, 2010; Rosenfeld et al. 2013; Dutrey et al. 2017), analysis of prior observations have not yet constrained the exact shape of this gradient.”
• Complex organic molecules in protoplanetary disks (2013, background): “Analysis of CO line observations also identified the lack of a vertical temprature gradient in this disk (see, e.g., Piétu et al. 2007).”
• A SPATIALLY RESOLVED VERTICAL TEMPERATURE GRADIENT IN THE HD 163296 DISK (2013, background): “Determining the structure of a disk using optically thick CO lines is difficult, and so previous studies have leveraged observations of multiple lines to break the model degeneracies (Dartois et al. 2003; Piétu et al. 2007).”
• Accretion disks in luminous young stellar objects (2015, methodology): “Spatially resolved line emission and chemical analysis have therefore been achieved mostly by making use of simple molecules (e.g., Pietu et al., 2007; Dutrey et al., 2014).”
• Measuring turbulence in TW Hydrae with ALMA: methods and limitations (2016, methodology): “In the following we give a brief description of the parametric model but refer the reader to Dartois et al. (2003) and Piétu et al. (2007) for a thorough model description and fitting methodology.”
• A SPATIALLY RESOLVED INNER HOLE IN THE DISK AROUND GM AURIGAE (2009, background): “Sev- eral recent millimeter studies have resolved inner emission cavities for disks with infrared SED deficits through direct imaging observations, e.g. TW Hya (Calvet et al. 2002; Hughes et al. 2007), LkHα 330 (Brown et al. 2007, 2008), and LkCa 15 (Piétu et al. 2007; Espaillat et al. 2008).”
• PROTOPLANETARY DISK STRUCTURES IN OPHIUCHUS. II. EXTENSION TO FAINTER SOURCES (2010, background): “…2007a; Hughes et al. 2008; Isella et al. 2009), clearly established the presence of vertical temperature and density gradients (Dartois et al. 2003; Piétu et al. 2007), and even identified disks with large central cavities that exhibit very little dust emission (Piétu et al. 2006; Hughes et al.…”
• Chemistry in Disks. IV. Benchmarking gas-grain chemical models with surface reactions (2010, background): “The disk has a radius of 800 AU, an accretion ratėM = 10−8 M⊙ yr−1, a viscosity parameterα = 0.01, and a massM ≃ 0.07M⊙ (Dutrey et al., 1997; Piétu et al., 2007).”
• Molecules with ALMA at Planet-forming Scales (MAPS). I. Program Overview and Highlights (2021, methodology): “…Teague et al. 2020; Podio et al. 2020; van’t Hoff et al. 2020), but vertical chemical structures are also accessible in moderately inclined disks (Piétu et al. 2007; Semenov et al. 2008; Rosenfeld et al. 2013; Pinte et al. 2018a; Paneque-Carreno et al. 2021; Rich et al. 2021), such as the ones…”
• Gas density drops inside dust cavities of transitional disks around young stars observed with ALMA (2015, unknown): “They were modeled as axisymmetric dust disks with inner cavities (e.g. Strom et al. 1989; Brown et al. 2007; Espaillat etal.”