skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Planet Formation in AB Aurigae: Imaging of the Inner Gaseous Spirals Observed inside the Dust Cavity

Abstract

We report the results of ALMA observations of a protoplanetary disk surrounding the Herbig Ae star AB Aurigae. We obtained high-resolution (0.″1; 14 au) images in {sup 12}CO J = 2 − 1 emission and in the dust continuum at the wavelength of 1.3 mm. The continuum emission is detected at the center and at the ring with a radius ( r ) of ∼120 au. The CO emission is dominated by two prominent spirals within the dust ring. These spirals are trailing and appear to be about 4 times brighter than their surrounding medium. Their kinematics is consistent with Keplerian rotation at an inclination of 23°. The apparent two-arm-spiral pattern is best explained by tidal disturbances created by an unseen companion located at r of 60–80 au, with dust confined in the pressure bumps created outside this companion orbit. An additional companion at r of 30 au, coinciding with the peak CO brightness and a large pitch angle of the spiral, would help to explain the overall emptiness of the cavity. Alternative mechanisms to excite the spirals are discussed. The origin of the large pitch angle detected here remains puzzling.

Authors:
; ;  [1]; ; ; ;  [2];  [3];  [4];  [5];  [6];  [7];  [8];  [9];  [10];  [11]
  1. Academia Sinica, Institute of Astronomy and Astrophysics, Taipei, Taiwan (China)
  2. Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, alle Geoffroy Saint-Hilaire, F-33615 Pessac (France)
  3. Department of Physics, National Taiwan University, Taiwan (China)
  4. Division of Liberal Arts, Kogakuin University, 1-24-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo 163-8677 (Japan)
  5. Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan)
  6. College of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512 (Japan)
  7. IRAM, 300 rue de la Piscine, Domaine Universitaire, F-38406 Saint-Martin-d’Hères (France)
  8. Division of Particle and Astrophysical Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602 (Japan)
  9. National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States)
  10. Subaru Telescope, National Astronomical Observatory of Japan, 650 North Aohoku Place, Hilo, HI 96720 (United States)
  11. Astrobiology Center of NINS 2-21-1, Osawa, Mitaka, Tokyo, 181-8588 (Japan)
Publication Date:
OSTI Identifier:
22663653
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 840; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BIOMEDICAL RADIOGRAPHY; BRIGHTNESS; CARBON 12; CARBON MONOXIDE; DISTURBANCES; DUSTS; EMISSION; ORBITS; PLANETS; PROTOPLANETS; RESOLUTION; ROTATION; STARS; WAVELENGTHS

Citation Formats

Tang, Ya-Wen, Gu, Pin-Gao, Ho, Paul T. P., Guilloteau, Stephane, Dutrey, Anne, Chapillon, Edwige, Folco, Emmanuel di, Muto, Takayuki, Shen, Bo-Ting, Inutsuka, Shu-ichiro, Momose, Munetake, Pietu, Vincent, Fukagawa, Misato, Corder, Stuartt, Ohashi, Nagayoshi, and Hashimoto, Jun, E-mail: ywtang@asiaa.sinica.edu.tw. Planet Formation in AB Aurigae: Imaging of the Inner Gaseous Spirals Observed inside the Dust Cavity. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA6AF7.
Tang, Ya-Wen, Gu, Pin-Gao, Ho, Paul T. P., Guilloteau, Stephane, Dutrey, Anne, Chapillon, Edwige, Folco, Emmanuel di, Muto, Takayuki, Shen, Bo-Ting, Inutsuka, Shu-ichiro, Momose, Munetake, Pietu, Vincent, Fukagawa, Misato, Corder, Stuartt, Ohashi, Nagayoshi, & Hashimoto, Jun, E-mail: ywtang@asiaa.sinica.edu.tw. Planet Formation in AB Aurigae: Imaging of the Inner Gaseous Spirals Observed inside the Dust Cavity. United States. doi:10.3847/1538-4357/AA6AF7.
Tang, Ya-Wen, Gu, Pin-Gao, Ho, Paul T. P., Guilloteau, Stephane, Dutrey, Anne, Chapillon, Edwige, Folco, Emmanuel di, Muto, Takayuki, Shen, Bo-Ting, Inutsuka, Shu-ichiro, Momose, Munetake, Pietu, Vincent, Fukagawa, Misato, Corder, Stuartt, Ohashi, Nagayoshi, and Hashimoto, Jun, E-mail: ywtang@asiaa.sinica.edu.tw. Mon . "Planet Formation in AB Aurigae: Imaging of the Inner Gaseous Spirals Observed inside the Dust Cavity". United States. doi:10.3847/1538-4357/AA6AF7.
@article{osti_22663653,
title = {Planet Formation in AB Aurigae: Imaging of the Inner Gaseous Spirals Observed inside the Dust Cavity},
author = {Tang, Ya-Wen and Gu, Pin-Gao and Ho, Paul T. P. and Guilloteau, Stephane and Dutrey, Anne and Chapillon, Edwige and Folco, Emmanuel di and Muto, Takayuki and Shen, Bo-Ting and Inutsuka, Shu-ichiro and Momose, Munetake and Pietu, Vincent and Fukagawa, Misato and Corder, Stuartt and Ohashi, Nagayoshi and Hashimoto, Jun, E-mail: ywtang@asiaa.sinica.edu.tw},
abstractNote = {We report the results of ALMA observations of a protoplanetary disk surrounding the Herbig Ae star AB Aurigae. We obtained high-resolution (0.″1; 14 au) images in {sup 12}CO J = 2 − 1 emission and in the dust continuum at the wavelength of 1.3 mm. The continuum emission is detected at the center and at the ring with a radius ( r ) of ∼120 au. The CO emission is dominated by two prominent spirals within the dust ring. These spirals are trailing and appear to be about 4 times brighter than their surrounding medium. Their kinematics is consistent with Keplerian rotation at an inclination of 23°. The apparent two-arm-spiral pattern is best explained by tidal disturbances created by an unseen companion located at r of 60–80 au, with dust confined in the pressure bumps created outside this companion orbit. An additional companion at r of 30 au, coinciding with the peak CO brightness and a large pitch angle of the spiral, would help to explain the overall emptiness of the cavity. Alternative mechanisms to excite the spirals are discussed. The origin of the large pitch angle detected here remains puzzling.},
doi = {10.3847/1538-4357/AA6AF7},
journal = {Astrophysical Journal},
number = 1,
volume = 840,
place = {United States},
year = {Mon May 01 00:00:00 EDT 2017},
month = {Mon May 01 00:00:00 EDT 2017}
}
  • We report high-resolution 1.6 {mu}m polarized intensity (PI) images of the circumstellar disk around the Herbig Ae star AB Aur at a radial distance of 22 AU (0.''15) up to 554 AU (3.''85), which have been obtained by the high-contrast instrument HiCIAO with the dual-beam polarimetry. We revealed complicated and asymmetrical structures in the inner part ({approx}<140 AU) of the disk while confirming the previously reported outer (r {approx}> 200 AU) spiral structure. We have imaged a double ring structure at {approx}40 and {approx}100 AU and a ring-like gap between the two. We found a significant discrepancy of inclination anglesmore » between two rings, which may indicate that the disk of AB Aur is warped. Furthermore, we found seven dips (the typical size is {approx}45 AU or less) within two rings, as well as three prominent PI peaks at {approx}40 AU. The observed structures, including a bumpy double ring, a ring-like gap, and a warped disk in the innermost regions, provide essential information for understanding the formation mechanism of recently detected wide-orbit (r > 20 AU) planets.« less
  • The Kepler mission has discovered more than 4000 exoplanet candidates. Many of them are in systems with tightly packed inner planets. Inside-out planet formation (IOPF) has been proposed as a scenario to explain these systems. It involves sequential in situ planet formation at the local pressure maximum of a retreating dead zone inner boundary (DZIB). Pebbles accumulate at this pressure trap, which builds up a pebble ring and then a planet. The planet is expected to grow in mass until it opens a gap, which helps to both truncate pebble accretion and also induce DZIB retreat that sets the location ofmore » formation of the next planet. This simple scenario may be modified if the planet undergoes significant migration from its formation location. Thus, planet–disk interactions play a crucial role in the IOPF scenario. Here we present numerical simulations that first assess the degree of migration for planets of various masses that are forming at the DZIB of an active accretion disk, where the effective viscosity is undergoing a rapid increase in the radially inward direction. We find that torques exerted on the planet by the disk tend to trap the planet at a location very close to the initial pressure maximum where it formed. We then study gap opening by these planets to assess at what mass a significant gap is created. Finally, we present a simple model for DZIB retreat due to penetration of X-rays from the star to the disk midplane. Overall, these simulations help to quantify both the mass scale of first (“Vulcan”) planet formation and the orbital separation to the location of second planet formation.« less
  • Recent coronagraphic imaging of the AB Aurigae disk has revealed a region of low polarized scattered light suggestive of perturbations from a planet at a radius of {approx}100 AU. We model this darkened region using our fully non-plane-parallel radiative-transfer code combined with a simple hydrostatic equilibrium approximation to self-consistently solve for the structure of the disk surface as seen in scattered light. By comparing the observations to our models, we find that the observations are consistent with the absence of a planet, with an upper limit of 1 M {sub J}.
  • We present the highest-resolution study to date of the interstellar medium (ISM) in galaxies undergoing ram pressure stripping, using Hubble Space Telescope BVI imaging of NGC 4522 and NGC 4402, Virgo Cluster spirals that are well known to be experiencing intracluster medium (ICM) ram pressure. We find that throughout most of both galaxies, the main dust lane has a fairly well-defined edge, with a population of giant molecular cloud (GMC) sized (tens- to hundreds-of-pc scale), isolated, highly extincting dust clouds located up to ∼1.5 kpc radially beyond it. Outside of these dense clouds, the area has little or no diffusemore » dust extinction, indicating that the clouds have decoupled from the lower-density ISM material that has already been stripped. Several of the dust clouds have elongated morphologies that indicate active ram pressure, including two large (kpc scale) filaments in NGC 4402 that are elongated in the projected ICM wind direction. We calculate a lower limit on the H I + H{sub 2} masses of these clouds based on their dust extinctions and find that a correction factor of ∼10 gives cloud masses consistent with those measured in CO for clouds of similar diameters, probably due to the complicating factors of foreground light, cloud substructure, and resolution limitations. Assuming that the clouds' actual masses are consistent with those of GMCs of similar diameters (∼10{sup 4}-10{sup 5} M {sub ☉}), we estimate that only a small fraction (∼1%-10%) of the original H I + H{sub 2} remains in the parts of the disks with decoupled clouds. Based on Hα images, a similar fraction of star formation persists in these regions, 2%-3% of the estimated pre-stripping star formation rate. We find that the decoupled cloud lifetimes may be up to 150-200 Myr.« less
  • We describe and constrain the origins of interstellar medium (ISM) structures likely created by ongoing intracluster medium (ICM) ram pressure stripping in two Virgo Cluster spirals, NGC 4522 and NGC 4402, using Hubble Space Telescope (HST) BVI images of dust extinction and stars, as well as supplementary H i, H α , and radio continuum images. With a spatial resolution of ∼10 pc in the HST images, this is the highest-resolution study to date of the physical processes that occur during an ICM–ISM ram pressure stripping interaction, ram pressure stripping's effects on the multi-phase, multi-density ISM, and the formation andmore » evolution of ram-pressure-stripped tails. In dust extinction, we view the leading side of NGC 4402 and the trailing side of NGC 4522, and so we see distinct types of features in both. In both galaxies, we identify some regions where dense clouds are decoupling or have decoupled and others where it appears that kiloparsec-sized sections of the ISM are moving coherently. NGC 4522 has experienced stronger, more recent pressure and has the “jellyfish” morphology characteristic of some ram-pressure-stripped galaxies. Its stripped tail extends up from the disk plane in continuous upturns of dust and stars curving up to ∼2 kpc above the disk plane. On the other side of the galaxy, there is a kinematically and morphologically distinct extraplanar arm of young, blue stars and ISM above a mostly stripped portion of the disk, and between it and the disk plane are decoupled dust clouds that have not been completely stripped. The leading side of NGC 4402 contains two kiloparsec-scale linear dust filaments with complex substructure that have partially decoupled from the surrounding ISM. NGC 4402 also contains long dust ridges, suggesting that large parts of the ISM are being pushed out at once. Both galaxies contain long ridges of polarized radio continuum emission indicating the presence of large-scale, ordered magnetic fields. We propose that magnetic fields could bind together gas of different densities, causing nearby gas of different densities to be stripped at the same rate and creating the large, coherent dust ridges and upturns. A number of factors likely play roles in determining what types of structures form as a result of ram pressure, including ram pressure strength and history, the location within the galaxy relative to the leading side, and pre-existing substructure in the ISM that may be bound together by magnetic fields during stripping.« less