{"title":"之前发生了什么?","authors":"Per-Gunnar Valegård, L. Waters, C. Dominik","doi":"10.1051/0004-6361/202039802","DOIUrl":null,"url":null,"abstract":"We seek to find the precursors of the Herbig Ae/Be stars in the solar vicinity within 500 pc from the Sun. We do this by creating an optically selected sample of intermediate mass T-Tauri stars (IMTT stars) here defined as stars of masses $1.5 M_{\\odot}\\leq M_* \\leq 5 M_{\\odot}$ and spectral type between F and K3, from literature. We use literature optical photometry (0.4-1.25$\\mu$m) and distances determined from Gaia DR2 parallax measurements together with Kurucz stellar model spectra to place the stars in a HR-diagram. With Siess evolutionary tracks we identify intermediate mass T-Tauri stars from literature and derive masses and ages. We use Spitzer spectra to classify the disks around the stars into Meeus Group I and Group II disks based on their [F$_{30}$/F$_{13.5}$] spectral index. We also examine the 10$\\mu$m silicate dust grain emission and identify emission from Polycyclic Aromatic Hydrocarbons (PAH). From this we build a qualitative picture of the disks around the intermediate mass T-Tauri stars and compare this with available spatially resolved images at infrared and at sub-millimeter wavelengths to confirm our classification. We find 49 intermediate mass T-Tauri stars with infrared excess. The identified disks are similar to the older Herbig Ae/Be stars in disk geometries and silicate dust grain population. Spatially resolved images at infra-red and sub-mm wavelengths suggest gaps and spirals are also present around the younger precursors to the Herbig Ae/Be stars. Comparing the timescale of stellar evolution towards the main sequence and current models of protoplanetary disk evolution the similarity between Herbig Ae/Be stars and the intermediate mass T-Tauri stars points towards an evolution of Group I and Group II disks that are disconnected, and that they represent two different evolutionary paths.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"68 1","pages":""},"PeriodicalIF":27.8000,"publicationDate":"2021-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"9","resultStr":"{\"title\":\"What happened before?\",\"authors\":\"Per-Gunnar Valegård, L. Waters, C. Dominik\",\"doi\":\"10.1051/0004-6361/202039802\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"We seek to find the precursors of the Herbig Ae/Be stars in the solar vicinity within 500 pc from the Sun. We do this by creating an optically selected sample of intermediate mass T-Tauri stars (IMTT stars) here defined as stars of masses $1.5 M_{\\\\odot}\\\\leq M_* \\\\leq 5 M_{\\\\odot}$ and spectral type between F and K3, from literature. We use literature optical photometry (0.4-1.25$\\\\mu$m) and distances determined from Gaia DR2 parallax measurements together with Kurucz stellar model spectra to place the stars in a HR-diagram. With Siess evolutionary tracks we identify intermediate mass T-Tauri stars from literature and derive masses and ages. We use Spitzer spectra to classify the disks around the stars into Meeus Group I and Group II disks based on their [F$_{30}$/F$_{13.5}$] spectral index. We also examine the 10$\\\\mu$m silicate dust grain emission and identify emission from Polycyclic Aromatic Hydrocarbons (PAH). From this we build a qualitative picture of the disks around the intermediate mass T-Tauri stars and compare this with available spatially resolved images at infrared and at sub-millimeter wavelengths to confirm our classification. We find 49 intermediate mass T-Tauri stars with infrared excess. The identified disks are similar to the older Herbig Ae/Be stars in disk geometries and silicate dust grain population. Spatially resolved images at infra-red and sub-mm wavelengths suggest gaps and spirals are also present around the younger precursors to the Herbig Ae/Be stars. Comparing the timescale of stellar evolution towards the main sequence and current models of protoplanetary disk evolution the similarity between Herbig Ae/Be stars and the intermediate mass T-Tauri stars points towards an evolution of Group I and Group II disks that are disconnected, and that they represent two different evolutionary paths.\",\"PeriodicalId\":785,\"journal\":{\"name\":\"The Astronomy and Astrophysics Review\",\"volume\":\"68 1\",\"pages\":\"\"},\"PeriodicalIF\":27.8000,\"publicationDate\":\"2021-04-29\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"9\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"The Astronomy and Astrophysics Review\",\"FirstCategoryId\":\"4\",\"ListUrlMain\":\"https://doi.org/10.1051/0004-6361/202039802\",\"RegionNum\":1,\"RegionCategory\":\"物理与天体物理\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"ASTRONOMY & ASTROPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"The Astronomy and Astrophysics Review","FirstCategoryId":"4","ListUrlMain":"https://doi.org/10.1051/0004-6361/202039802","RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
We seek to find the precursors of the Herbig Ae/Be stars in the solar vicinity within 500 pc from the Sun. We do this by creating an optically selected sample of intermediate mass T-Tauri stars (IMTT stars) here defined as stars of masses $1.5 M_{\odot}\leq M_* \leq 5 M_{\odot}$ and spectral type between F and K3, from literature. We use literature optical photometry (0.4-1.25$\mu$m) and distances determined from Gaia DR2 parallax measurements together with Kurucz stellar model spectra to place the stars in a HR-diagram. With Siess evolutionary tracks we identify intermediate mass T-Tauri stars from literature and derive masses and ages. We use Spitzer spectra to classify the disks around the stars into Meeus Group I and Group II disks based on their [F$_{30}$/F$_{13.5}$] spectral index. We also examine the 10$\mu$m silicate dust grain emission and identify emission from Polycyclic Aromatic Hydrocarbons (PAH). From this we build a qualitative picture of the disks around the intermediate mass T-Tauri stars and compare this with available spatially resolved images at infrared and at sub-millimeter wavelengths to confirm our classification. We find 49 intermediate mass T-Tauri stars with infrared excess. The identified disks are similar to the older Herbig Ae/Be stars in disk geometries and silicate dust grain population. Spatially resolved images at infra-red and sub-mm wavelengths suggest gaps and spirals are also present around the younger precursors to the Herbig Ae/Be stars. Comparing the timescale of stellar evolution towards the main sequence and current models of protoplanetary disk evolution the similarity between Herbig Ae/Be stars and the intermediate mass T-Tauri stars points towards an evolution of Group I and Group II disks that are disconnected, and that they represent two different evolutionary paths.
期刊介绍:
The Astronomy and Astrophysics Review is a journal that covers all areas of astronomy and astrophysics. It includes subjects related to other fields such as laboratory or particle physics, cosmic ray physics, studies in the solar system, astrobiology, instrumentation, and computational and statistical methods with specific astronomical applications. The frequency of review articles depends on the level of activity in different areas. The journal focuses on publishing review articles that are scientifically rigorous and easily comprehensible. These articles serve as a valuable resource for scientists, students, researchers, and lecturers who want to explore new or unfamiliar fields. The journal is abstracted and indexed in various databases including the Astrophysics Data System (ADS), BFI List, CNKI, CNPIEC, Current Contents/Physical, Chemical and Earth Sciences, Dimensions, EBSCO Academic Search, EI Compendex, Japanese Science and Technology, and more.