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

3. What Is Unknown? 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 How and why the disks evolve? Disks seem to disappear completely Mass loss rate seems to be variable

4. Spectroscopy of Be Stars at the Ritter Observatory 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 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

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

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

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 V K Polarization UBUB BVBV EW (H  )

22.  Aquarii

24. Be Binary Candidates NameV-mag EW(H  ), A EW Lac5.446 V777 Cas7.0 20  45 V695 Mon6.545 HD 2067736.9 0  43 105 Tau5.942 HD 2086825.941  Per 4.2 30  40 HD 2029044.432 DX Eri5.930 Gem 4.28

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 R=5000  10000 Patrol for line profile and EW variations R>10000Detection of the orbital motion R>40000Line profile fine structure 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