Outline Introduction The disks of B[e] supergiants Formation mechanism(s) of B[e] supergiant stars’ disks Conclusions Probing the structure and dynamics of B[e] supergiant stars’ disks Michaela Kraus Tartu Observatory March 16, 2016 M. Kraus Probing the structure and dynamics of B[e] supergiant stars’ disks Outline Introduction The disks of B[e] supergiants Formation mechanism(s) of B[e] supergiant stars’ disks Conclusions 1 Introduction 2 The disks of B[e] supergiants 3 Formation mechanism(s) of B[e] supergiant stars’ disks 4 Conclusions M. Kraus Probing the structure and dynamics of B[e] supergiant stars’ disks Follow-up infrared surveys (Allen & Swings 1972; Allen 1973, 1974; Allen & Glass 1974, 1975) reveal two distinct populations of emission-line stars emission-line stars with normal stellar IR colors emission-line stars with IR excess emission due to hot dust Conti (1976) suggested to call these peculiar B-type emission-line stars with forbidden lines and dust as B[e] stars Identification of more and more stars with similar properties Definition of general criteria is needed. Outline Introduction The disks of B[e] supergiants Formation mechanism(s) of B[e] supergiant stars’ disks Conclusions Introduction - B[e] Stars Discovery of B[e] Stars Geisel (1970) found infrared (IR) excess emission in a sample of emission-line stars of spectral type B with low-excitation emission lines (especially Fe II and [Fe III]). M. Kraus Probing the structure and dynamics of B[e] supergiant stars’ disks Conti (1976) suggested to call these peculiar B-type emission-line stars with forbidden lines and dust as B[e] stars Identification of more and more stars with similar properties Definition of general criteria is needed. Outline Introduction The disks of B[e] supergiants Formation mechanism(s) of B[e] supergiant stars’ disks Conclusions Introduction - B[e] Stars Discovery of B[e] Stars Geisel (1970) found infrared (IR) excess emission in a sample of emission-line stars of spectral type B with low-excitation emission lines (especially Fe II and [Fe III]). Follow-up infrared surveys (Allen & Swings 1972; Allen 1973, 1974; Allen & Glass 1974, 1975) reveal two distinct populations of emission-line stars emission-line stars with normal stellar IR colors emission-line stars with IR excess emission due to hot dust M. Kraus Probing the structure and dynamics of B[e] supergiant stars’ disks Identification of more and more stars with similar properties Definition of general criteria is needed. Outline Introduction The disks of B[e] supergiants Formation mechanism(s) of B[e] supergiant stars’ disks Conclusions Introduction - B[e] Stars Discovery of B[e] Stars Geisel (1970) found infrared (IR) excess emission in a sample of emission-line stars of spectral type B with low-excitation emission lines (especially Fe II and [Fe III]). Follow-up infrared surveys (Allen & Swings 1972; Allen 1973, 1974; Allen & Glass 1974, 1975) reveal two distinct populations of emission-line stars emission-line stars with normal stellar IR colors emission-line stars with IR excess emission due to hot dust Conti (1976) suggested to call these peculiar B-type emission-line stars with forbidden lines and dust as B[e] stars M. Kraus Probing the structure and dynamics of B[e] supergiant stars’ disks Definition of general criteria is needed. Outline Introduction The disks of B[e] supergiants Formation mechanism(s) of B[e] supergiant stars’ disks Conclusions Introduction - B[e] Stars Discovery of B[e] Stars Geisel (1970) found infrared (IR) excess emission in a sample of emission-line stars of spectral type B with low-excitation emission lines (especially Fe II and [Fe III]). Follow-up infrared surveys (Allen & Swings 1972; Allen 1973, 1974; Allen & Glass 1974, 1975) reveal two distinct populations of emission-line stars emission-line stars with normal stellar IR colors emission-line stars with IR excess emission due to hot dust Conti (1976) suggested to call these peculiar B-type emission-line stars with forbidden lines and dust as B[e] stars Identification of more and more stars with similar properties M. Kraus Probing the structure and dynamics of B[e] supergiant stars’ disks Outline Introduction The disks of B[e] supergiants Formation mechanism(s) of B[e] supergiant stars’ disks Conclusions Introduction - B[e] Stars Discovery of B[e] Stars Geisel (1970) found infrared (IR) excess emission in a sample of emission-line stars of spectral type B with low-excitation emission lines (especially Fe II and [Fe III]). Follow-up infrared surveys (Allen & Swings 1972; Allen 1973, 1974; Allen & Glass 1974, 1975) reveal two distinct populations of emission-line stars emission-line stars with normal stellar IR colors emission-line stars with IR excess emission due to hot dust Conti (1976) suggested to call these peculiar B-type emission-line stars with forbidden lines and dust as B[e] stars Identification of more and more stars with similar properties Definition of general criteria is needed. M. Kraus Probing the structure and dynamics of B[e] supergiant stars’ disks Outline Introduction The disks of B[e] supergiants Formation mechanism(s) of B[e] supergiant stars’ disks Conclusions Introduction - B[e] Stars Defining criteria for B[e] stars strong Balmer emission lines low-excitation permitted emission lines, predominantly of singly ionized metals, in particular of Fe II; forbidden emission lines of [O I] and [Fe II]; a strong near/mid IR excess due to hot (T 1000 K) circumstellar dust. ' M. Kraus Probing the structure and dynamics of B[e] supergiant stars’ disks + Characteristics can be found in stars in various evolutionary stages! Classification of the stars with the B[e] phenomenon by Lamers et al. (1998) + + + + pre-MS stars: post-MS stars: post-MS stars: interacting binaries: Herbig B[e] compact PNe B[e] B[e] supergiants symbiotic stars The remaining 50% could not be classified and are kept as a separate group of unclassified∼ B[e] stars. Outline Introduction The disks of B[e] supergiants Formation mechanism(s) of B[e] supergiant stars’ disks Conclusions Introduction - B[e] Stars Criteria are mainly based on emission features seen in optical spectra These features represent specific physical conditions within the circumstellar material, but contain no information on the star itself ! M. Kraus Probing the structure and dynamics of B[e] supergiant stars’ disks + + + + pre-MS stars: post-MS stars: post-MS stars: interacting binaries: Herbig B[e] compact PNe B[e] B[e] supergiants symbiotic stars The remaining 50% could not be classified and are kept as a separate group of unclassified∼ B[e] stars. Outline Introduction The disks of B[e] supergiants Formation mechanism(s) of B[e] supergiant stars’ disks Conclusions Introduction - B[e] Stars Criteria are mainly based on emission features seen in optical spectra These features represent specific physical conditions within the circumstellar material, but contain no information on the star itself ! + Characteristics can be found in stars in various evolutionary stages! Classification of the stars with the B[e] phenomenon by Lamers et al. (1998) M. Kraus Probing the structure and dynamics of B[e] supergiant stars’ disks Outline Introduction The disks of B[e] supergiants Formation mechanism(s) of B[e] supergiant stars’ disks Conclusions Introduction - B[e] Stars Criteria are mainly based on emission features seen in optical spectra These features represent specific physical conditions within the circumstellar material, but contain no information on the star itself ! + Characteristics can be found in stars in various evolutionary stages! Classification of the stars with the B[e] phenomenon by Lamers et al. (1998) + + + + pre-MS stars: post-MS stars: post-MS stars: interacting binaries: Herbig B[e] compact PNe B[e] B[e] supergiants symbiotic stars The remaining 50% could not be classified and are kept as a separate group of unclassified∼ B[e] stars. M. Kraus Probing the structure and dynamics of B[e] supergiant stars’ disks Outline Introduction The disks of B[e] supergiants Formation mechanism(s) of B[e] supergiant stars’ disks Conclusions Introduction - B[e] Stars Herbig B[e] cPNe B[e] B[e] supergiant symbiotic B[e] B-type B-type obscured O-type B-type obscured hot spectrum PMS star white dwarf supergiant compact obj. forbidden reflection PN nebula high-density associated emission nebula non-spherical nebula lines wind dust and PMS high-density high-density accretion Balmer accretion dusty disk (outflowing ?) disk lines disk disk (d) V921 Sco-A Hen 2-90 Artist’s view Ant nebula Herbig B[e] cPNe supergiant symbiotic M. Kraus Probing the structure and dynamics of B[e] supergiant stars’ disks Outline Introduction The disks of B[e] supergiants Formation mechanism(s) of B[e] supergiant stars’ disks Conclusions Introduction - B[e] Supergiants Additional characteristics of B[e] supergiants: Stars are supergiants, i.e. log L =L 4:0 ∗ ≥ Chemically processed materiel indicating an evolved evolutionary phase Hybrid spectra, i.e. simultaneously narrow low-excitation emission lines and broad absorption features of higher-excitation lines Density contrast between equatorial and polar wind of 100 – 1000 LMC B[e] supergiant R 126 (IUE spectrum) Si IV Si IV 1 Hot stellar wind with v 1800 km s− (Zickgraf et al.1 1985)' 1 Lines with FWHM of 20 – 30 km s− M. Kraus Probing the structure and dynamics of B[e] supergiant stars’ disks Outline Introduction The disks of B[e] supergiants Formation mechanism(s) of B[e] supergiant stars’ disks Conclusions Introduction - B[e] Supergiants Hybrid wind model suggested by Zickgraf et al. (1985). M. Kraus Probing the structure and dynamics of B[e] supergiant stars’ disks Outline Introduction The disks of B[e] supergiants Formation mechanism(s) of B[e] supergiant stars’ disks Conclusions The disks of B[e] supergiants Observational evidence for the disk 1.