1. A New Group of Dust-Forming Hot Stars Anatoly Miroshnichenko Pulkovo Observatory (Saint-Petersburg, Russia) Max-Planck-Institut fur Radioastronomie (Bonn, Germany) University of Toledo (Ohio, USA)

2. Collaborators Valentina Klochkova, Vladimir Panchuk, Eugene Chentsov, Maxim Yushkin Anatoly Kusakin Special Astrophysical Observatory of the Rus. Acad. Sciences, Russia GAISh, Russia Karen BjorkmanU. of Toledo, OH, USA Richard Rudy, David Lynch, Steve Mazuk, Catherine Venturini Aerospace Corp., CA, USA Richard GrayAppalachian State U., NC, USA Nadine MansetCFHT Corp., Canada Kenesken KuratovFesenkov Astrophys. Inst., Казахстан Kenneth HinkleNOAO, AZ, USA Richard PuetterU.of CA @ San Diego,USA Thomas GandetLizzard Hollow Obs., AZ, USA Brad PerryNASA Langley Center, VA, USA Hugo Levato, Monica GrossoComplejo El Leoncito, Argentina

3. Main Subject Dust-Forming Stars circumstellar  interstellar  circumstellar Cool Stars T eff ~ 3000 K + Strong Outflow Hot stars T eff  10000 K + Shielding from UV Colliding Winds AGB & post-AGB Dust T sub ~ 1500 K WR, LBV с L/L  > 10 5

4. Outline Early-Type Stars with Circumstellar Dust B[e] Stars Properties of B[e] Stars with Warm Dust Search for New Candidates and Results of the Initial Observations Nature and Evolutionary State Conclusions

5. Objects with Circumstellar Dust which Include a Hot Star Herbig Ae/Be stars (warm & cold dust) Vega-type stars (cold dust) Symbiotic Stars (M-giant + OB-subdwarf, white dwarf, or neutron star; warm dust) VV Cep stars (M-supergiant + OB dwarf ?; warm dust) Wolf-Rayet stars (carbon-rich or binary; warm dust) Luminous Blue Variables (cold dust) Proto-Planetary & Planetary Nebulae (cold dust) B[e] stars

6. B[e] Stars: History of Studies Discovery: Allen & Swings (1976, A&A, 47, 293) 65 objects with forbidden lines and IR excesses at =2  m Possible explanations for the phenomenon: Formation of a Planetary Nebula Interaction of an OB star with a cool companion Direct ejection of matter by a massive OB star Follow up classification: Herbig Ae/Be stars (7), LBV (3), PNe (17), symbiotic (8), supergiants (7) 28 objects – uncertain classification

7. Additions and Systematization Lists of similar objects Carlson & Henize (1979, Vistas in Astronomy, 23, 213): 20 early-type stars with strong emission-line spectra Dong & Hu (1991, Chin. A&A, 15, 275): ~200 early-type stars with strong IR-excesses (IRAS,V-[25] > 8 mag) Systematization Attempt Lamers et al. (1998, A&A, 340, 117) – 5 categories of B[e] stars: sgB[e], pmsB[e], cPNB[e], SymbB[e], unclB[e] New group of unclB[e] – B[e] stars with warm dust B[e]WD

8. IRAS color-color diagram  +  - B[e]WD,  - Ае/Ве stars,  - Vega-type stars,  - symbiotic stars, + - VV Cep

9. B[e] Stars with Warm Dust (B[e]WD) Selection Criteria: Spectra: early-type + strong Balmer emission lines IRAS colors:  0.5 < lg F 12 /F 25 < +0.1  1.1 < lg F 60 /F 25 <  0.3 Presentation as a group: Sheikina, Miroshnichenko, & Corporon 1999 (IAU Coll. 175, Alicante, Spain) - 11 objects Miroshnichenko, Bjorkman, Chentsov, Klochkova 2002 (IAU Coll. 187, Florida, USA) - 19 objects Miroshnichenko et al. 2004 (203 AAS Meeting, Atlanta, USA) – 19 objects + 28 candidates

10. Observations TelescopeObservatoryType of data 6-mSAO, Russiaopt.spectra, R=15000-60000 3.6-mCFHT, USAopt.spectra, R=60000 8-m 3-m Gemini, Chile Lick Obs., USA NASA IRTF, USA IR spectra,  2.5  m, R~75000 IR spectra, =0.8  2.5  m, R~300 IR spectra, =3  14  m, R~600 2.1-mMcDonald Obs., USAopt.spectra, R=60000 2.1-mCompl. El Leoncito, Argentinaopt.spectra, R=10000-15000 1.5-mTenerife, SpainJHK photometry 1-mTien-Shan Obs., KazakhstanUBVRIJHK photometry 0.5&0.75-mSAAO, South AfricaUBVRIJHKL photometry 0.8-mDark Sky Obs., USAopt.spectra, R~3000 0.5-m 0.3-m Tien-Shan Obs., Kazakhstan Lizard Hollow Obs., USA WBVR photometry UBVRI photometry

11. Properties of B[e]WD NameIRASVSp.T.E(B-V)Lg L/L  D (kpc) EW(H  ) AS 7803549+5602 11.3  0.1 B2/40.9 3.9  0.1 2.5115 CI Cam04156+5552 9.0  11.6 B0/2+?1.1 5.0  0.54646 250 HD 45677 06259  13017.6  8.5 B20.2 3.5  0.4 0.5170 HD 50138 06491  06546.5  6.8 B50.15 2.9  0.2 0.360 AS 160 07370  243810.9  0.1 B10.7 4.0  0.1 4.0:300 Hen3-140 08128  5000 10.1B2/80.3 3.1  0.2 2.0 Hen3-298 09350  5314 10.1B31.35: 3434 232 Hen3-303 09369  5406 13.1:B 3434 HD 85567 09489  6044 8.6B20.4 4.0  0.3 1.531 CPD  57 287410136  5736 10.1B3/51.95.7:2.5 CPD  52 924316031  5255 10.3B3/41.8 5.7  0.3 4.960 HD 327083 17117  40169.7  0.1 B1/2+F1.8 5.0  0.41212 36 Hen3-1398 17213  3841 10.6O91.1 5.3  0.2 3.3 MWC 300 18267  060611.6  0.2 B11.2 5.1  0.1 1.8145 MWC 62319545+3058 10.7  0.2 B2+K1.44.1:2.4:122 AS 38120047+330514.4B1+K2.2 4.9  0.2 4.0  80 MWC 34220212+3920 10.2  10.9 B1/21.4 4.1  0.4 1.0 170  220 V669 Cep22248+6058 12.2  0.2 B5+K0.9 2.7  0.31  1.566  187 MWC 65722407+600812.5B11.6 3.7  0.3 2.0180

12. Spectral Energy Distribution

13. Photometric Properties Frequently observed objects: HD 45677, HD 50138, MWC 300, MWC 342, CI Cam Variability Types: Short-term irregular :  V ~ 0.1 – 0.5 mag Long-term gradual brightness changes :  V ~ 0.5 – 2 mag (MWC 342, HD 45677) Short-term outbursts :  V ~ 3 mag (CI Cam, 1998 March 31) Cyclic: from weeks to years Near-IR variations:  K ~ 0.5 mag

17. Spectral Properties H  line profiles are mostly double-peaked Single- or double-peaked narrow metallic emission lines (FWHM ~ 100 km s -1 ) Strong and variable Balmer emission lines Forbidden lines [O I] 6300 & 6364A, [N II] 5577, 6348, & 6384A, sometimes [S III] 6312A

18. Spectrral Variations

19. H  Line Profiles

20. Absorption Lines

21. IR Spectra

22. Basic Physical Parameters Spectral Type of the Hot Companion: O9-B8 Spectral Type of the Cool Companion : F, K Initial Mass : 2 - 40 M  Luminosity: 500 – 10 6 L  Circumstellar Gas distribution: disk-like Circumstellar Dust distribution: not clear (probably circumbinary disk)

23. Hertzsprung-Russell Diagram

24. Nature and Evolutionary State Majority of (all?) objects – Main-Sequence and after Known Binary systems: 1.MWC 623: B2 V + K2 III (Zickgraf 2001, A&A, 375, 122) 2.CI Cam: B[e] sg + black hole? (Miroshnichenko et al. 2002, A&A, 390, 627) 3.AS 381: B1 I + K II-III (Miroshnichenko et al. 2002, A&A, 383, 171) 4.V669 Cep: B5 V + K (Miroshnichenko et al. 2002, A&A, 388, 563) 5.HD 327083: B1 I + F I (Miroshnichenko et al. 2003, A&A, 406, 673) Suspected Binaries: 1.MWC 342 (Miroshnichenko & Corporon 1999, A&A, 349, 126) 2.MWC 657 (Miroshnichenko et al. 2000, A&AS, 147, 5) 3.HD 85567 & Hen 1398 (Miroshnichenko et al. 2001, A&A, 371, 600) 4.MWC 300 (Miroshnichenko et al. 2004, A&A, 417, 731) Objects with a Controversial State: 1.HD 45677 & HD 50138 – suggested Herbig Ве stars

25. Enlarging the Group 1.Stars of the main group are relatively bright V ~ 9  12 mag, K ~ 3  7 mag, [12  m]~ 0  3.5 mag. The IRAS sensitivity limit : ~ 6 mag 2. Large range of the luminosities 3. Release of the deep sky surveys in 2003: 2MASS (JHK) and USNO-B1.0 (5 non-standard optical bands) Basis for a new search for B[e]WD in the IRAS catalogs

26. Search Strategy & Difficulties Selection criteria Color-indices [12]  [25] & [25]  [60] Close positions in the IRAS & 2MASS catalogs Selection of the brightest 2MASS object in the IRAS error box Positional coincidence in the 2MASS & USNO catalogs Difficulties Selection criteria are only positional & photometric Separation of reddened hot stars from cool stars Confusion with RV Tau stars

27. New Photometric Criterion  - RV Tau; + - cool stars  B[e]WD & new candidates

28. Search Results  4500 IR sources was found in the B[e]WD box 60 objects satisfying the selection criteria were found among  2500 objects with  b   50   20 objects are thrown out after comparison with dusty RV Tau stars Initial observations of 40 B[e]WD candidates have been started: 1.Multicolor optical photometry 2.Optical spectroscopy of low- and high-resolution 3.Low-resolution IR spectroscopy

29. Results of the Initial Observations September 2003 – April 2004 Photometry (WBVR, UBVRI) - 10 objects Spectroscopy DSO : 3800  5600 A, R~1800 – 10 objects БТА : 5200  6600 A, R~60000 – 2 objects CFHT : H , SiII 6347, Na D, R~100000 – 11 objects Lick Obs. : 0.8  2.5  m, R~1300 – 5 objects NASA IRTF : 3 – 14  m, R~100 – 2 objects It is shown that 8 objects are indeed B/A stars 2 new emission-line objects have been found

30. New Objects IRAS 00470+6429 BTAUSNO, 2MASS, IRTF

31. New Objects CFHT

32. Positional Distribution  - main group objects,  - new candidates

33. Conclusions A new large group (61 objects to date) of hot stars with circumstellar dust is discovered Dust formation seems to be either on-going or has stopped recently Objects: either binary systems undergoing a rapid mass exchange or single stars with unusually strong winds Investigation of the group may lead to new ideas for evolutionary theories of single/binary stars and refinement of our understanding of dist formation