new candidates for dust-forming hot stars anatoly miroshnichenko max-planck-institut fur...
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New Candidates for Dust-FormingHot Stars
Anatoly Miroshnichenko
Max-Planck-Institut fur Radioastronomie (Bonn, Germany)
University of Toledo (Ohio, USA)
Pulkovo Observatory (Saint-Petersburg, Russia)
CollaboratorsValentina Klochkova, Vladimir Panchuk, Eugene Chentsov, Maxim Yushkin
Anatoly Kusakin
Special Astrophysical Observatory of the Russian Academy of Sciences, Russia
Sternberg Institute. Moscow, Russia
Karen Bjorkman U. of Toledo, OH, USA
Richard Rudy, David Lynch, Steve Mazuk, Catherine Venturini
Aerospace Corp., CA, USA
Richard Gray Appalachian State U., NC, USA
Nadine Manset CFHT Corp., Canada
Kenesken Kuratov Fesenkov Astrophys. Inst., Kazakhstan
Kenneth Hinkle NOAO, AZ, USA
Richard Puetter U.of CA @ San Diego,USA
Thomas Gandet Lizzard Hollow Obs., AZ, USA
Brad Perry NASA Langley Research Center, VA, USA
Hugo Levato, Monica Grosso Complejo El Leoncito, Argentina
Main Subject
Dust-Forming Stars
circumstellar interstellar circumstellar
Cool Stars
Teff ~ 3000 K
+
Strong Outflow
Hot stars
Teff 10000 K
+
Shielding from UV
Colliding Winds
AGB & post-AGB
Dust
Tsub ~ 1500 K
WR, LBV L/L > 105
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
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
B[e] Stars: History of StudiesDiscovery: 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
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 AttemptLamers 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
IRAS Colors of B[e] StarsSymbiotic +
HAeBe �LBV *
PPN&PN Unclass. B[e]WD
IRAS color-color diagram
- B[e]WD, - Ае/Ве stars, - Vega-type stars, - symbiotic stars, ++ - VV Cep
B[e] Stars with Warm Dust (B[e]WD)
Selection Criteria:Spectra: early-type + strong Balmer emission lines
IRAS colors: 0.5 < lg F12/F25 < +0.2
1.1 < lg F60/F25 < 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
Properties of B[e]WDName IRAS V Sp.T. E(B-V) Lg L/L D (kpc) EW(H)
AS 78 03549+5602 11.30.1 B2/4 0.9 3.9 0.1 2.5 115
CI Cam 04156+5552 9.011.6 B0/2+? 1.1 5.0 0.5 46 250
HD 45677 062591301 7.68.5 B2 0.2 3.5 0.4 0.5 170
HD 50138 064910654 6.56.8 B5 0.15 2.9 0.2 0.3 60
AS 160 073702438 10.90.1 B1 0.7 4.0 0.1 4.0: 300
Hen3-140 081285000 10.1 B2/8 0.3 3.1 0.2 2.0
Hen3-298 093505314 10.1 B3 1.3 5: 34 232
Hen3-303 093695406 13.1: B 34
HD 85567 094896044 8.6 B2 0.4 4.0 0.3 1.5 31
CPD57 2874 101365736 10.1 B3/5 1.9 5.7: 2.5
CPD52 9243 160315255 10.3 B3/4 1.8 5.7 0.3 4.9 60
HD 327083 171174016 9.70.1 B1/2+F 1.8 5.00.4 12 36
Hen3-1398 172133841 10.6 O9 1.1 5.3 0.2 3.3
MWC 300 182670606 11.60.2 B1 1.2 5.10.1 1.8 145
MWC 623 19545+3058 10.70.2 B2+K 1.4 4.1: 2.4: 122
AS 381 20047+3305 14.4 B1+K 2.2 4.9 0.2 4.0 80
MWC 342 20212+3920 10.210.9 B1/2 1.4 4.1 0.4 1.0 170220
V669 Cep 22248+6058 12.20.2 B5+K 0.9 2.7 0.3 11.5 66187
MWC 657 22407+6008 12.5 B1 1.6 3.7 0.3 2.0 180
Spectral Energy Distribution
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
Photometric Variations
Photometric Variations
Photometric Variations
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
Spectral Variations
H Line Profiles
Absorption Lines
IR Spectra
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 – 106 L
• Circumstellar Gas distribution: disk-like• Circumstellar Dust distribution: not clear
(probably circumbinary disk)
Hertzsprung-Russell Diagram
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
Enlarging the Group
1. Stars of the main group are relatively bright V ~ 912 mag, K ~ 37 mag, [12m]~ 03.5 mag. The IRAS sensitivity limit : ~ 6 mag
2. Large range of the luminosities3. 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
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
New Photometric Criterion
- RV Tau; + - cool stars
B[e]WD & new candidates
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
Results of the Initial ObservationsSeptember 2003 – June 2004
Photometry• (WBVR, UBVRI) - 10 objects
Spectroscopy• DSO : 38005600 A, R~1800 – 10 objects• BТА, 6-m : 52006600 A, R~60000 – 2 objects• CFHT : H, SiII 6347, Na D, R~100000 – 11 objects• Lick Obs. : 0.8 2.5m, R~1300 – 7 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
New Objects
IRAS 00470+6429
6-m Russian telescope USNO, 2MASS, IRTF
IRAS 07080+0605
New ObjectsCFHT
Positional Distribution
- main group objects, - new candidates
Nature and Evolutionary State of B[e]WD
Single stars? Too high mass loss rates in non-luminous objects (>10-6 M yr-1 for 310 M stars)
Binaries? More likely, but the secondary detection rate is low
Not pre-main-sequence objects – lack of cold dust and association with star-forming regions
Not post-AGB objects – lack of cold dust and too high gravity
Possible Binary Parameters
RY Sct: orbital period – 11.1 day
masses – 8–52 M
Sp.T. – OB + OB
distance – 2 kpc
Angular size of the circumbinary dusty disk – 1 arcsec
HDE 327083: orbital period – 56.5 or 173.5 days
masses - ~25 M (total)
Sp.T. – B1 + F
distance – 1.50.5 kpcGG Car (eclipsing binary): orbital period – 31 day
RV Curve for HDE 327083
- photospheric lines
� - FeII emissions
Conclusions
• A new large group (60 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 dust formation