Periodic Reporting for period 1 - WANDA (Winds ANd Disk structures near and Afar)
Periodo di rendicontazione: 2022-05-01 al 2024-10-31
We live in the era when planets around stars other than our Sun, i.e. exo-planets, have been detected in large numbers, and yet one of the biggest question in science, to understand when and how they form, is still open. This question is key to shed light on the origin of our own planet, and to understand where other planets like our own formed, to further comprehend whether we are a unique case in the Universe or not. The answer to this question is strongly intertwined with a deep knowledge of the morphology of protoplanetary disks, the birthplace of planets, and of the physical processes shaping these morphologies.
Protoplanetary disks made of gas and dust are routinely detected around young stellar objects and they are being extensively studied in nearby (distance ca. 100 – 400 pc) star-forming regions. We have studied their properties, such as mass, size, and how the mass is distributed within the disk, key to determine what kind of planets would form. Each of these properties is regulated by several processes affecting the evolution of the disk, divided into internal processes, such as the accretion of material from the disk onto the central star or the ejection of material through winds, and external processes, such as external photoevaporation and dynamical interactions.
In the last decade new astonishing images of disks have been obtained especially using the Atacama Large Millimeter/submillimeter Array (ALMA) and near-infrared high spatial resolution instruments, e.g. SPHERE on the Very Large Telescope (VLT). These images are causing a shift of paradigm: protoplanetary disks are not smooth, rather highly structured. Are these structures the signposts of planets? What other mechanisms can give origin to these structures? These questions are key to understand planet formation, yet they are still matter of debate.
More open questions arise when one considers that the impact of the environment dramatically increases in more distant (more than 400 – 1000 pc) and more massive star-forming regions, environments that best resemble the typical star-forming regions of when the currently known exo-planet hosting stars formed ca. 4–10 Gyrs ago. The external processes acting in these regions reduce the typical sizes of disks, strongly impacting the possibility of structures to form, and possibly modifying what kind of planetary systems can form in them. However, how exactly these processes impact the disks and the subsequent formation of planets is definitely not understood.
The goal of this program is to explore the relations between disk structures and a number of disk processes able to explain the presence and morphology of these structures, including but not limited to the disk winds, binaries, or to the presence of planets. In turn, in this program these key relations will be used as basis to study the ability to form planets in disks located in more massive and more distant star-forming regions than studied to date, where most stars and planets form.
Protoplanetary disks made of gas and dust are routinely detected around young stellar objects and they are being extensively studied in nearby (distance ca. 100 – 400 pc) star-forming regions. We have studied their properties, such as mass, size, and how the mass is distributed within the disk, key to determine what kind of planets would form. Each of these properties is regulated by several processes affecting the evolution of the disk, divided into internal processes, such as the accretion of material from the disk onto the central star or the ejection of material through winds, and external processes, such as external photoevaporation and dynamical interactions.
In the last decade new astonishing images of disks have been obtained especially using the Atacama Large Millimeter/submillimeter Array (ALMA) and near-infrared high spatial resolution instruments, e.g. SPHERE on the Very Large Telescope (VLT). These images are causing a shift of paradigm: protoplanetary disks are not smooth, rather highly structured. Are these structures the signposts of planets? What other mechanisms can give origin to these structures? These questions are key to understand planet formation, yet they are still matter of debate.
More open questions arise when one considers that the impact of the environment dramatically increases in more distant (more than 400 – 1000 pc) and more massive star-forming regions, environments that best resemble the typical star-forming regions of when the currently known exo-planet hosting stars formed ca. 4–10 Gyrs ago. The external processes acting in these regions reduce the typical sizes of disks, strongly impacting the possibility of structures to form, and possibly modifying what kind of planetary systems can form in them. However, how exactly these processes impact the disks and the subsequent formation of planets is definitely not understood.
The goal of this program is to explore the relations between disk structures and a number of disk processes able to explain the presence and morphology of these structures, including but not limited to the disk winds, binaries, or to the presence of planets. In turn, in this program these key relations will be used as basis to study the ability to form planets in disks located in more massive and more distant star-forming regions than studied to date, where most stars and planets form.
In the first two years of the project, the WANDA team has started several projects with the following goals:
- studying the relation between observed disk substructures and disk wind properties
- understanding whether substructures in disks are related to changes in the accretion properties
- exploring the possibility that spectroscopic binaries can be the cause of the large cavities observed in disks
- understanding the effects of external photoevaporation on disks and finding the best tracers of internal and externally-driven winds
- exploring combining ALMA and spectroscopy the effect of massive stars on disk evolution.
During these projects, several techniques are being improved, in particular on fitting the spectra of young stars to derive stellar and accretion properties, fitting the high-resolution spectra to study emission lines, and fitting ALMA data to find structures and disk radii.
On top of these projects, the team members have written several successful proposals to follow-up on spectroscopic studies of accretion and wind properties in disks with structures, as well as ALMA proposals to detect substructures in disks. Other proposals were submitted to JWST and VLT to follow-up on externally photoevaporated disks.
Among the main result, we have detected disk winds in the inner part of the best known planet-hosting disk, PDS70, shown new spectacular images of externally photoevaporated disks and measured their physical sizes, expanded the grid of templates to study accretion rates, and shown where external photoevaporation leaves a significant imprint on disks.
- studying the relation between observed disk substructures and disk wind properties
- understanding whether substructures in disks are related to changes in the accretion properties
- exploring the possibility that spectroscopic binaries can be the cause of the large cavities observed in disks
- understanding the effects of external photoevaporation on disks and finding the best tracers of internal and externally-driven winds
- exploring combining ALMA and spectroscopy the effect of massive stars on disk evolution.
During these projects, several techniques are being improved, in particular on fitting the spectra of young stars to derive stellar and accretion properties, fitting the high-resolution spectra to study emission lines, and fitting ALMA data to find structures and disk radii.
On top of these projects, the team members have written several successful proposals to follow-up on spectroscopic studies of accretion and wind properties in disks with structures, as well as ALMA proposals to detect substructures in disks. Other proposals were submitted to JWST and VLT to follow-up on externally photoevaporated disks.
Among the main result, we have detected disk winds in the inner part of the best known planet-hosting disk, PDS70, shown new spectacular images of externally photoevaporated disks and measured their physical sizes, expanded the grid of templates to study accretion rates, and shown where external photoevaporation leaves a significant imprint on disks.
The new studies of winds and accretion properties we are performing stresses how the inner and outer disk properties are connected, and possibly show that planets are seen in disks when winds are the strongest.
Our results are showing how much disks are shaped by massive stars, and hint to new ways to study the effect of external photoevaporation, which must be followed up with more data and detailed analyses.
Our results are showing how much disks are shaped by massive stars, and hint to new ways to study the effect of external photoevaporation, which must be followed up with more data and detailed analyses.