Year: 2018
Type: article
Abstract: We examine whether various characteristics of planet-driven spiral arms can be used to constrain the masses of unseen planets and their positions within their disks. By carrying out two-dimensional hydrodynamic simulations varying planet mass and disk gas temperature, we find that a larger number of spiral arms form with a smaller planet mass and a lower disk temperature. A planet excites two or more spiral arms interior to its orbit for a range of disk temperatures characterized by the disk aspect ratio , whereas exterior to a planet’s orbit multiple spiral arms can form only in cold disks with . Constraining the planet mass with the pitch angle of spiral arms requires accurate disk temperature measurements that might be challenging even with ALMA. However, the property that the pitch angle of planet-driven spiral arms decreases away from the planet can be a powerful diagnostic to determine whether the planet is located interior or exterior to the observed spirals. The arm-to-arm separations increase as a function of planet mass, consistent with previous studies; however, the exact slope depends on disk temperature as well as the radial location where the arm-to-arm separations are measured. We apply these diagnostics to the spiral arms seen in MWC 758 and Elias 2–27. As shown in Bae et al., planet-driven spiral arms can create concentric rings and gaps, which can produce a more dominant observable signature than spiral arms under certain circumstances. We discuss the observability of planet-driven spiral arms versus rings and gaps.
Source: The Astrophysical Journal
Authors: Jaehan Bae, Zhaohuan Zhu
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Awards: G2782160116, MRI: Acquisition of an Extreme GPU Cluster for Interdisciplinary Research, XSEDE 2.0: Integrating, Enabling and Enhancing National Cyberinfrastructure with Expanding Community Involvement, RECENT HIGH ANGULAR RESOLUTION OBSERVATIONS (E.G. ALMA VLT) OF PROTOPLANETARY DISKS HAVE BEGUN TO REVEAL COMPLICATED STRUCTURE (E.G. SPIRAL ARMS GAPS RINGS ETC.). IN PRINCIPLE SUCH OBSERVATIONS CAN PROVIDE CONSTRAINTS ON DISK DYNAMICS AND FOR THE FIRST TIME REVEAL THE PHYSICAL PROCESSES WHICH CONTROL THE PLANET FORMATION PROCESS. HOWEVER THIS REQUIRES REALISTIC THEORETICAL MODELS OF DISK DYNAMICS INCLUDING A PROPER TREATMENT OF MHD EFFECTS DUST GROWTH SETTLING AND FEEDBACK AS WELL AS ACCURATE RADIATIVE TRANSFER CALCULATIONS THAT CAN GENERATE SYNTHETIC IMAGES FOR COMPARISON TO DATA. THE GOAL OF THIS PROJECT IS TO COMPUTE SUCH MODELS. WE WILL CALCULATE THE MOST REALISTIC GLOBAL NUMERICAL MODELS OF PROTOPLANETARY DISKS AND DISK-PLANET INTERACTION TO DATE COMPUTE SYNTHETIC IMAGES OF THE MODELS BASED ON A SELF-CONSISTENT TREATMENT OF THE DUST DYNAMICS IN THE DISK AND COMPARE THESE MODELS TO INTERPRET EXISTING DATA AND TO PREDICT FUTURE OBSERVATIONS. IN PARTICULAR WE WILL COMPARE OUR MODELS WITH OBSERVATIONS FROM EXISTING NASA SPACE MISSIONS (E.G. SPITZER HERSCHEL) AND GROUND BASED TELESCOPES (E.G. ALMA EVLA VLT SUBARU GEMINI) AND WE WILL MAKE PREDICTIONS FOR FUTURE OBSERVATIONS. OVER YEARS OUR TEAM HAS BEEN BUILDING TOOLS TO ACHIEVE SUCH GOALS. WE HAVE STUDIED NON-IDEAL MHD EFFECTS ON DISK TURBULENCE DUST PARTICLE DYNAMICS IN GASEOUS DISKS PLANET-DISK INTERACTION AND OTHER ASTROPHYSICAL DISK RELATED PROBLEMS. NOW ADOPTING NOVEL NUMERICAL TECHNIQUES IN OUR NEWLY DEVELOPED 3-D MAGNETOHYDRODYNAMIC (MHD) CODE ATHENA++ WE CAN FINALLY PUT ALL THESE PIECES TOGETHER AND CONSTRUCT FIRST-PRINCIPLE GLOBAL SIMULATIONS TO BE DIRECTLY COMPARED WITH OBSERVATIONS. WE PLAN TO USE THIS NEW CODE TO (1) STUDY HOW PROTOPLANETARY DISKS ACCRETE BY CARRYING OUT GLOBAL 3-D MHD SIMULATIONS INCLUDING ALL IMPORTANT NON-IDEAL MHD EFFECTS. (2) INCLUDE DUST PARTICLES AND YOUNG PLANETS IN OUR SIMULATIONS TO STUDY DUST DYNAMICS PLANETESIMAL FORMATION AND THE OBSERVATIONAL SIGNATURES OF YOUNG PLANETS IN PROTOPLANETARY DISKS. SINCE MOST DISK EMISSION COMES FROM DUST THIS STEP IS ESSENTIAL FOR CONNECTING SIMULATIONS WITH OBSERVATIONS. (3) POST PROCESS OUR GLOBAL 3-D SIMULATIONS WITH 3-D MONTE CARLO RADIATIVE TRANSFER CODES TO GENERATE OBSERVATIONAL SIGNATURES OF DISK TURBULENCE AND YOUNG PLANETS IN DISKS. COMPARISONS WITH CURRENT OBSERVATIONS AND PREDICTIONS FOR FUTURE OBSERVATIONS WILL BE MADE. THESE FIRST-PRINCIPLE CALCULATIONS (INCLUDING MHD EFFECTS DUST-GAS DYNAMICS AND RADIATIVE TRANSFER) WILL ADDRESS FUNDAMENTAL QUESTIONS ON PROTOPLANETARY DISKS AND ALLOW US TO STUDY PLANET FORMATION PROCESSES IN DETAIL. THE PREDICTIONS FROM THESE SIMULATIONS WILL NOT ONLY BE COMPARED WITH OBSERVATIONS (E.G. ALMA) DIRECTLY BUT ALSO SERVE AS A FOUNDATION FOR UNDERSTANDING PLANET FORMATION AND EXOPLANET PROPERTIES FOR FUTURE SPACE MISSIONS (E.G. JWST WFIRST TESS)., THIS PROJECT WILL INVESTIGATE THE STABILITY OF PROPAGATING SPIRAL WAVES IN PROTOPLANETARY DISKS BY CARRYING OUT THREE-DIMENSIONAL NUMERICAL SIMULATIONS. SPIRAL WAVES IN PROTOPLANETARY DISKS ARE SUBJECT TO RESONANT INTERACTIONS WITH INERTIAL MODES. THIS CAN LEAD TO THE DESTABILIZATION OF THE SPIRAL WAVES INTO SMALL TURBULENT EDDIES BY TRANSFERRING WAVE ENERGY TO INERTIAL MODES -- SPIRAL WAVE INSTABILITY. IMPROVING UPON OUR PRIOR WORK THE PROPOSED PROJECT WILL AIM TO STUDY STABILITY OF THE SPIRAL WAVES EXCITED BY A PLANETARY COMPANION AND TO EXAMINE THE EFFECTS OF DISK THERMODYNAMICS TO THE INSTABILITY. THE NECESSARY CODE ELEMENTS HAVE BEEN IMPLEMENTED IN AND TESTED WITH ASTROPHYSICAL (MAGNETO-)HYDRODYNAMIC CODES FARGO3D ATHENA AND PLUTO BY THE TEAM MEMBERS. USING THE PROPOSED SIMULATIONS WE WILL ASSESS (1) HOW EFFICIENTLY SPIRAL WAVES ARE DESTABILIZED BY THE INSTABILITY; (2) HOW MASS AND ANGULAR MOMENTUM TRANSPORT VIA SPIRAL WAVES CHANGE IN RESPONSE TO THE INSTABILITY; AND (3) HOW DUST DIFFUSES/COLLECTS WITHIN THE TURBULENCE PRODUCED BY THE INSTABILITY. THE RESULTS WILL HAVE POTENTIAL IMPACT IN UNDERSTANDING THE MASS TRANSPORT AND THE FORMATION OF PLANETESIMALS/PLANETS IN THE PROTO-SOLAR NEBULA AS WELL AS IN EXTRASOLAR PROTOPLANETARY SYSTEMS., G7770318571
OpenAlex ID: W2769552660