On the Mass Accretion Rates of Herbig Ae/Be Stars. Magnetospheric Accretion or Boundary Layer?
Understanding how young stars gain their masses through disk-to-star accretion is of paramount importance in astrophysics. It affects our knowledge about the early stellar evolution, the disk lifetime and dissipation processes, the way the planets form on the smallest scales, or the connection to ma...
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| Format: | Article |
| Language: | English |
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MDPI AG
2020-05-01
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| Series: | Galaxies |
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| Online Access: | https://www.mdpi.com/2075-4434/8/2/39 |
| _version_ | 1797568733087006720 |
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| author | Ignacio Mendigutía |
| author_facet | Ignacio Mendigutía |
| author_sort | Ignacio Mendigutía |
| collection | DOAJ |
| description | Understanding how young stars gain their masses through disk-to-star accretion is of paramount importance in astrophysics. It affects our knowledge about the early stellar evolution, the disk lifetime and dissipation processes, the way the planets form on the smallest scales, or the connection to macroscopic parameters characterizing star-forming regions on the largest ones, among others. In turn, mass accretion rate estimates depend on the accretion paradigm assumed. For low-mass T Tauri stars with strong magnetic fields there is consensus that magnetospheric accretion (MA) is the driving mechanism, but the transfer of mass in massive young stellar objects with weak or negligible magnetic fields probably occurs directly from the disk to the star through a hot boundary layer (BL). The intermediate-mass Herbig Ae/Be (HAeBe) stars bridge the gap between both previous regimes and are still optically visible during the pre-main sequence phase, thus constituting a unique opportunity to test a possible change of accretion mode from MA to BL. This review deals with our estimates of accretion rates in HAeBes, critically discussing the different accretion paradigms. It shows that although mounting evidence supports that MA may extend to late-type HAes but not to early-type HBes, there is not yet a consensus on the validity of this scenario versus the BL one. Based on MA and BL shock modeling, it is argued that the ultraviolet regime could significantly contribute in the future to discriminating between these competing accretion scenarios. |
| first_indexed | 2024-03-10T20:01:08Z |
| format | Article |
| id | doaj.art-3a284cc53acc4426b92f20d94c99a1cd |
| institution | Directory Open Access Journal |
| issn | 2075-4434 |
| language | English |
| last_indexed | 2024-03-10T20:01:08Z |
| publishDate | 2020-05-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Galaxies |
| spelling | doaj.art-3a284cc53acc4426b92f20d94c99a1cd2023-11-19T23:31:49ZengMDPI AGGalaxies2075-44342020-05-01823910.3390/galaxies8020039On the Mass Accretion Rates of Herbig Ae/Be Stars. Magnetospheric Accretion or Boundary Layer?Ignacio Mendigutía0Centro de Astrobiología (CSIC-INTA), Departamento de Astrofísica, ESA-ESAC Campus, 28691 Madrid, SpainUnderstanding how young stars gain their masses through disk-to-star accretion is of paramount importance in astrophysics. It affects our knowledge about the early stellar evolution, the disk lifetime and dissipation processes, the way the planets form on the smallest scales, or the connection to macroscopic parameters characterizing star-forming regions on the largest ones, among others. In turn, mass accretion rate estimates depend on the accretion paradigm assumed. For low-mass T Tauri stars with strong magnetic fields there is consensus that magnetospheric accretion (MA) is the driving mechanism, but the transfer of mass in massive young stellar objects with weak or negligible magnetic fields probably occurs directly from the disk to the star through a hot boundary layer (BL). The intermediate-mass Herbig Ae/Be (HAeBe) stars bridge the gap between both previous regimes and are still optically visible during the pre-main sequence phase, thus constituting a unique opportunity to test a possible change of accretion mode from MA to BL. This review deals with our estimates of accretion rates in HAeBes, critically discussing the different accretion paradigms. It shows that although mounting evidence supports that MA may extend to late-type HAes but not to early-type HBes, there is not yet a consensus on the validity of this scenario versus the BL one. Based on MA and BL shock modeling, it is argued that the ultraviolet regime could significantly contribute in the future to discriminating between these competing accretion scenarios.https://www.mdpi.com/2075-4434/8/2/39young starspre-main sequence objectsT Tauri starsHerbig Ae/Be starsprotoplanetary disksaccretion disks |
| spellingShingle | Ignacio Mendigutía On the Mass Accretion Rates of Herbig Ae/Be Stars. Magnetospheric Accretion or Boundary Layer? Galaxies young stars pre-main sequence objects T Tauri stars Herbig Ae/Be stars protoplanetary disks accretion disks |
| title | On the Mass Accretion Rates of Herbig Ae/Be Stars. Magnetospheric Accretion or Boundary Layer? |
| title_full | On the Mass Accretion Rates of Herbig Ae/Be Stars. Magnetospheric Accretion or Boundary Layer? |
| title_fullStr | On the Mass Accretion Rates of Herbig Ae/Be Stars. Magnetospheric Accretion or Boundary Layer? |
| title_full_unstemmed | On the Mass Accretion Rates of Herbig Ae/Be Stars. Magnetospheric Accretion or Boundary Layer? |
| title_short | On the Mass Accretion Rates of Herbig Ae/Be Stars. Magnetospheric Accretion or Boundary Layer? |
| title_sort | on the mass accretion rates of herbig ae be stars magnetospheric accretion or boundary layer |
| topic | young stars pre-main sequence objects T Tauri stars Herbig Ae/Be stars protoplanetary disks accretion disks |
| url | https://www.mdpi.com/2075-4434/8/2/39 |
| work_keys_str_mv | AT ignaciomendigutia onthemassaccretionratesofherbigaebestarsmagnetosphericaccretionorboundarylayer |