be stars
Download
Skip this Video
Download Presentation
Be Stars

Loading in 2 Seconds...

play fullscreen
1 / 18

Be Stars - PowerPoint PPT Presentation


  • 175 Views
  • Uploaded on

Be Stars. Nicholas De Lucca. Classification. Spectral Class B Emission lines IR excess Be Main sequence Post main sequence B[e] Supergiant Pre-main sequence Planetary nebulae. M45. Be Stars. First observed 1867 - Angelo Secchi (1818-1878) Active hot star

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Be Stars' - dimaia


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
be stars

Be Stars

Nicholas De Lucca

classification
Classification
  • Spectral Class B
  • Emission lines
  • IR excess
  • Be
    • Main sequence
    • Post main sequence
  • B[e]
    • Supergiant
    • Pre-main sequence
    • Planetary nebulae
be stars1
Be Stars
  • First observed 1867 - Angelo Secchi (1818-1878)
  • Active hot star
  • 20% of all B stars, 60-70% in younger clusters
  • Oblate
  • Strong polar wind
  • High speed rotation
variability
Variability
  • Short Term
    • A few minutes or days
    • Photosphere oscillations?
  • Medium Term
    • Few years
    • Moving density pattern
  • Long Term
    • Few decades
    • B -> Be -> Be Shell
    • Reason unknown
rotation
Rotation
  • Keplerian
  • 0.5 Vc > V > 0.9 Vc
  • V > 300 km/s
b e stars
B[e] Stars
  • 1970’s
  • Lower circumstellar density
    • Allows forbidden emission
  • Higher IR excess
  • B[e] phenomenon versus B[e] Star
  • Regions of varying density
b e phenomenon criteria
B[e] Phenomenon Criteria
  • Balmer emission lines
  • Low excitation permitted emission lines
  • [FeII] and [OI] forbidden emission lines in the visual
  • Infrared excess
b e supergiants
B[e] Supergiants
  • L > 104LSun
  • Lower cimcumstellar density due to much larger size
  • Dust forms near edge of disk
herbig aeb e stars
Herbig AeB[e] Stars
  • Young Stellar Objects (YSO)
  • 2-8 MSun
  • Lack of nuclear burning
b e planetary nebulae
B[e] Planetary Nebulae
  • Ionized red giant gas shells
  • MRG < 8-10 MSun
  • May have [OIII], [SIII], [NeIII]
summary
Summary
  • Emission Lines
    • Permissible and forbidden
  • Variability
    • Short, medium and long term
  • Circumstellar disk
  • Strong Wind
  • Fast Rotation
references
References
  • Lamers, Henny J. G. L. M.; Zickgraf, Franz-Josef; de Winter, Dolf; Houziaux, Leo; Zorec, Janez, "An improved classification of B[e]-type stars", Astronomy and Astrophysics, v.340, p.117-128 (1998)
  • Michaela Kraus, Marcelo Borges Fernandes, Francisco X. de Ara´ujo, Henny J.G.L.M. Lamers, "The Compact Planetary Nebula B[e] Star Hen 2--90", San Francisco: Astronomical Society of the Pacific, 2006., p.125
  • Stee, P. Active Hot Stars. Observatoria de la Cote d’Azur. 1 Dec. 2006
  • Percy, John. “Gamma Cassiopeiae.” Variable Stars. American Association of Variable Star Observers. Oct. 2001
  • Buill, Christian. The Be Stars Atlas. 20 Oct. 2007
  • Jensen, Adam. AST 102. 2 Dec. 2006
  • Thinkquest.
ad