1 / 27

Spectra of the Brightest Be stars and Objects Description

Spectra of the Brightest Be stars and Objects Description. Anatoly Miroshnichenko University of North Carolina at Greensboro USA. Observational Features of Be Stars Temporal Behavior of Individual Objects Bright Objects for Monitoring.  Cassiopeae discovered in 1866. Be Stars.

koto
Download Presentation

Spectra of the Brightest Be stars and Objects Description

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. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Spectra of the Brightest Be stars and Objects Description Anatoly Miroshnichenko University of North Carolina at Greensboro USA • Observational Features of Be Stars • Temporal Behavior of Individual Objects • Bright Objects for Monitoring

  2.  Cassiopeae discovered in 1866 Be Stars Circumstellar gas has a flattened distribution (disk-like) • Main Properties: • Intermediate luminosity • Emission-line spectra • Rapid rotation

  3. What Is Unknown? • How and why the disks evolve? • Disks seem to disappear completely • Mass loss rate seems to be variable • Are Be stars single objects or binary systems? • 25% detected binaries in the brightest 240 Be stars • Weak-lined objects can be single or close binaries • Strong-lined objects can be wide binaries

  4. 9 non-overlapping orders, 70 Å each, range 52856600 Å. Includes spectral lines of FeII 5317 & 6383, HeI 5876, NaI 5889 & 5895, SiII 6347 & 6371, and H Spectral resolving power R (/) ~ 26000 Spectroscopy of Be Stars at the Ritter Observatory • 1-meter telescope with a fiberfed echelle spectrograph and a 1150x1150-pixel CCD in the Coude focus • Spectra of stars brighter than 7.5 mag can be obtained in 1 hour with a signal-to-noise ratio of ~100 • ~2000 spectra of ~ 45 Be stars obtained in 19912007

  5.  Cassiopeae

  6.  Cassiopeae

  7. 48 Librae V ~ 4.84.95 mag B4 IIIe D=15717 pc V sin i ~ 400 km/s

  8. 48 Librae

  9.  Canis Minoris V ~ 2.9 mag B8 Ve D=522 pc V sin i ~ 245 km/s Possible orbital periods: 218.5 days and 3 years Both not confirmed

  10.  Canis Minoris

  11.  Canis Minoris

  12.  Canis Minoris

  13.  Persei V ~ 4.2 mag B5 Ve D=21530 pc V sin i ~ 212 km/s

  14.  Persei

  15. 66 Oph V ~ 4.6 mag B2 Ve D=20740 pc V sin i ~ 240 km/s

  16. 66 Oph

  17.  Cassiopeae V ~ 4.5 mag B5 IIIe D=28080 pc V sin i ~ 220 km/s No line emission in 1970-s

  18.  Cassiopeae

  19. Orbital period vs. EW (H) • Conclusions: • Longer orbital period  larger disk  stronger lines • Later spectral type  smaller ionized disk area  weaker lines + - Be/X-ray binaries • - B1 4 Be binaries ° - B5  8 Be binaries

  20. What We Get Studying Binaries Most Be binaries are single-lined  secondaries are much fainter than primaries The brightness difference is V ~ 24 magnitudes Orbital periods and spectroscopic masses  companion separation  disk sizes The main disk responsible for the line emission and IR excess is around the primary companion The secondary may have some amount of circumstellar matter around it

  21.  Aquarii UB V K BV Polarization EW (H)

  22.  Aquarii

  23.  Aquarii

  24. Be Binary Candidates

  25. How and What to Look For • Regular low-resolution spectral observations: • search for dramatic variations (new disk formation or disappearance) • monitoring of long-term changes of the line strength Goals of higher-resolution spectroscopy

  26. Galactic Be Stars The only catalog of Galactic Be stars – Jaschek & Egret (1982) It contains 1159 objects down to ~13 mag About 30% of them may not be Be stars (we only know that they have H emission) The brightest part of the catalog has been cleaned: there are ~310 Be stars brighter than ~7.5 mag Fainter ones need to be observed spectroscopically and reclassfied

  27. Summary • Monitoring of bright Be star is important for finding the reasons for the phenomenon • Spectral resolution of 500020000 can be enough to search for condition changes in the disk and searching for orbital motion • Frequency of observations: twice a month when the changes are slow and as frequent as possible when rapid changes occur • Observations of objects fainter than ~7 mag are important to clean up the existing catalog of Galactic Be stars

More Related