A dichotomy in group II Herbig disks: ALMA gas disk height measurements show both shadowed large vertically extended disks and compact flat disks
arXiv:2211.12532 · doi:10.1051/0004-6361/202245137
Abstract
Herbig stars can be classified into group I and group II depending on the shape of the far-IR excess from the spectral energy distribution. This separation may be evolutionary and related to the vertical structure of these disks. We aim to determine the emission height of Herbig disks and compare the resulting vertical extent of both groups. ALMA Band 6 observations of 12CO emission lines at sufficient velocity and spatial resolution of eight Herbig disks (four group I and four group II sources) are used to determine the emission heights from the channel maps via geometrical methods developed in other works. We find that all group I disks are vertically extended with a height to radius ratio of at least 0.25, and for three of the disks the gas emission profile can be traced out to 200-500 au. The group II disks are divided between MWC 480 and HD 163296 which have similar emission height profiles as the group I disks, and AK Sco and HD 142666 which are very flat (not exceeding a height of 10 au) and more compact (<200 au in size). The brightness temperatures show no differences between the disks when the luminosity of the host star is accounted for. Our findings agree with previous work suggesting that group I disks are vertically extended and that group II disks are either large and self-shadowed or compact. Both MWC 480 and HD 163296 could be precursors of group I disks, which we see now before a cavity has formed that would allow irradiation of the outer parts of the disk. The very flat disks AK Sco and HD 142666 could be due to significant settling because of the advanced age of these disks (~20 instead of <10 Myr). These large differences in vertical structures are not reflected in the spectral energy distributions of these disks. More and deeper observations at higher spatial and velocity resolution are necessary to further characterize the Herbig sub-groups.
arXiv commentAccepted for publication in Astronomy and Astrophysics. 8 pages, 4 figures, plus appendices
References in corpus (46)
- SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
- Array Programming with NumPy
- Astropy: A Community Python Package for Astronomy
- Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
- The Disk Substructures at High Angular Resolution Project (DSHARP): I. Motivation, Sample, Calibration, and Overview
- The Mass Dependence Between Protoplanetary Disks and their Stellar Hosts
- Dust coagulation in protoplanetary disks: a rapid depletion of small grains
- The AKARI/IRC Mid-Infrared All-Sky Survey
- ISO spectroscopy of circumstellar dust in 14 Herbig Ae/Be systems: towards an understanding of dust processing
- Flaring vs. self-shadowed disks: the SEDs of Herbig Ae/Be stars
- The Disk Substructures at High Angular Resolution Project (DSHARP): II. Characteristics of Annular Substructures
- The effect of dust settling on the appearance of protoplanetary disks
- A Kinematical Detection of Two Embedded Jupiter Mass Planets in HD 163296
- A New Planet Around an M Dwarf: Revealing a Correlation Between Exoplanets and Stellar Mass
- Kinematic evidence for an embedded protoplanet in a circumstellar disc
- Molecules with ALMA at Planet-forming Scales (MAPS) I: Program Overview and Highlights
- Observations of edge-on protoplanetary disks with ALMA I. Results from continuum data
- The Connection between Submillimeter Continuum Flux and Binary Separation in Young Binaries: Evidence of Interaction between Stars and Disks
- Identifying gaps in flaring Herbig Ae/Be disks using spatially resolved mid-infrared imaging. Are all group I disks transitional?
- Molecules with ALMA at Planet-forming Scales (MAPS) IV: Emission Surfaces and Vertical Distribution of Molecules
- A stellar mass dependence of structured disks: a possible link with exoplanet demographics
- Mid-IR imaging of the transitional disk of HD169142: Measuring the size of the gap
- The structure of disks around intermediate-mass young stars from mid-infrared interferometry. Evidence for a population of group II disks with gaps
- Correlation between grain growth and disk geometry in Herbig Ae/Be systems
- Consistent dust and gas models for protoplanetary disks III. Models for selected objects from the FP7 DIANA project
- Spiral arms in the proto-planetary disc HD100453 detected with ALMA: evidence for binary-disc interaction and a vertical temperature gradient
- Homogeneous study of Herbig Ae/Be stars from spectral energy distributions and Gaia EDR3
- High-Resolution ALMA Observations of HD100546: Asymmetric Circumstellar Ring, and Circumplanetary Disk Upper Limits
- Spiral Arms and a Massive Dust Disk with non-Keplerian Kinematics: Possible Evidence for Gravitational Instability in the Disk of Elias 2-27
- A new planet candidate detected in a dust gap of the disc around HD 163296 through localised kinematic signatures. An observational validation of the Discminer
- Evolution of protoplanetary disks from their taxonomy in scattered light: Group I vs. Group II
- ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT) II: Vertical stratification of CO, CS, CN, HCO, and CHOH in a Class I disk
- Shadows and cavities in protoplanetary disks: HD163296, HD141569A, and HD150193A in polarized light
- ALMA reveals the anatomy of the mm-sized dust and molecular gas in the HD 97048 disk
- The structure of disks around Herbig Ae/Be stars as traced by CO ro-vibrational emission
- Directly tracing the vertical stratification of molecules in protoplanetary disks
- New millimeter CO observations of the gas-rich debris disks 49 Cet and HD 32297
- On the interplay between flaring and shadowing in disks around Herbig Ae/Be stars
- The mass and size of Herbig disks as seen by ALMA
- Gas temperature structure across transition disk cavities
- A 80 au cavity in the disk around HD 34282
- Probing the 2D temperature structure of protoplanetary disks with Herschel observations of high-J CO lines
- Investigating the Relative Gas and Small Dust Grain Surface Heights in Protoplanetary Disks
- Large dust gaps in the transitional disks of HD 100453 and HD 34282
- Vertically extended and asymmetric CN emission in the Elias 2-27 protoplanetary disk
- The California Legacy Survey II. Occurrence of Giant Planets Beyond the Ice line