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HD 108 and the Other Peculiar Of?p Stars: Still Puzzling Peter, Jean-Marie, and the Massive Star Community Yaël Nazé (Liège University), Nolan R. Walborn (STScI), and Maxime Spano (Geneva Observatory) Conti Vreux

Yaël Nazé (Liège University), Nolan R. Walborn (STScI), and Maxime Spano (Geneva Observatory)

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Conti. Vreux. HD 108 and the Other Peculiar Of?p Stars: Still Puzzling Peter, Jean-Marie, and the Massive Star Community. Yaël Nazé (Liège University), Nolan R. Walborn (STScI), and Maxime Spano (Geneva Observatory). Outline of the talk. Of?p, a long story… HD108 HD191612 HD148937 - PowerPoint PPT Presentation

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Page 1: Yaël Nazé (Liège University),  Nolan R. Walborn (STScI),  and Maxime Spano (Geneva Observatory)

HD 108 and the Other Peculiar Of?p Stars: Still Puzzling Peter, Jean-Marie, and the

Massive Star Community

Yaël Nazé (Liège University), Nolan R. Walborn (STScI),

and Maxime Spano (Geneva Observatory)

Conti Vreux

Page 2: Yaël Nazé (Liège University),  Nolan R. Walborn (STScI),  and Maxime Spano (Geneva Observatory)

Outline of the talk

Of?p, a long story…

• HD108

• HD191612

• HD148937

• Others…

• Conclusions

Page 3: Yaël Nazé (Liège University),  Nolan R. Walborn (STScI),  and Maxime Spano (Geneva Observatory)

Of?p, what is that for a spectral type ?

• The Of?p zoo : – introduced by N.R. Walborn in 1972,1973

– principal defining Of?p characteristic :

C III 4650 comparable to N III 4640+ narrow emission/PCyg in Balmer lines+ asymmetric/PCyg HeI lines+ peculiar wind lines in UV

– Rare : 3 Galactic objects

Page 4: Yaël Nazé (Liège University),  Nolan R. Walborn (STScI),  and Maxime Spano (Geneva Observatory)

HD108• My first job :

– Jean-Marie : “I have a bunch of spectra”– CIII, H lines, HeI lines variable (+ HeII4686)– 4542 cst

apparent ST changes : O4f?p O8.5fp (Nazé et al. 2001,2004)

– Not so new :• Andrillat, Fehrenbach, Swings & Vreux 1973

“Observations recentes du spectre de HD108 (Of)”• Vreux & Conti 1979 “Spectral variations in the Of

star HD108: are they periodic?”

Page 5: Yaël Nazé (Liège University),  Nolan R. Walborn (STScI),  and Maxime Spano (Geneva Observatory)

HD108

• What is it ?– Binary ? (Hutchings 1975, Aslanov & Barranikov 1989)

– Expanding atmosphere ? (Andrillat et al. 1973)

– Disc & jets ? (Underhill 1994)

– Wind variations ? (Vreux & Conti 1979)

– Disc & oscillations ? (Nazé et al. 2001)

– Magnetically confined wind ? (Nazé et al. 2001)

– XRB ? (Nazé et al. 2001)

Prob. not

No

No

?

?

?

?

Page 6: Yaël Nazé (Liège University),  Nolan R. Walborn (STScI),  and Maxime Spano (Geneva Observatory)

HD108

XMM observations from Jean-Marie :• A soft X-ray spectrum (T1=0.2-0.3 keV – dominates!, T2=1-3keV) • Luminous, but log(Lx/Lbol)= –6.1

(Nazé et al. 2004)

Not an XRB !

Page 7: Yaël Nazé (Liège University),  Nolan R. Walborn (STScI),  and Maxime Spano (Geneva Observatory)

HD191612• Just as HD 108…

– Spectral type : O6.5f?p O8fp – LPV with P=538d– Photometric variations too !– Binary with P=1540d(Walborn et al. 2003,2004, Nazé et al. 2007,

Howarth et al. 2007 )

HD108 too !

Page 8: Yaël Nazé (Liège University),  Nolan R. Walborn (STScI),  and Maxime Spano (Geneva Observatory)

HD191612

XMM, again…

Nearly identical high-E spectra !• Soft X-ray spectrum, with only ~30% of flux

(0.5-10keV) in the high T

• Broad lines (FWHM~1800km/s), overluminosity log(Lx/Lbol)= –6.1 to –6.2

• Variations! less X-rays when less visible

emissions & star fainter (Nazé et al. 2007)

is it phase-locked ? YES !

40%

New XMM observation taken at the same phase in the LPV cycle, but at +1.6 in orbital phase

Page 9: Yaël Nazé (Liège University),  Nolan R. Walborn (STScI),  and Maxime Spano (Geneva Observatory)

HD148937• Not just the same…

– Spectral type : O6f?p – Not a binary : Indeed… see Conti et al. 1977– LPV for HeII4686, H & H– Possible period : ~7d but sampling inadequate

(Nazé et al. 2008a,b)

– Additional monitoring with Coralie– Amplitude of variations from H to H– HeI5876 also variable !– Period of ~7d confirmed !

– What about the photometry ?

- May 8

- May 12

- May 15

- May 20

Page 10: Yaël Nazé (Liège University),  Nolan R. Walborn (STScI),  and Maxime Spano (Geneva Observatory)

An answer ?• HD 191612 : detection of a magnetic field !

– Zeeman signature in metallic & HeI lines – line-of-sight component : -220 +/- 38 G (Donati et al. 2006)

• HD148937 : – Line-of-sight component : -276 +/- 88 G (Hubrig et al. 2008)

• What about HD 108 ?

HD191612

Page 11: Yaël Nazé (Liège University),  Nolan R. Walborn (STScI),  and Maxime Spano (Geneva Observatory)

Others…

• In the MCs :a few ones were detected (Heydari-Malayeri & Melnick 1992, Walborn et al. 2000, Massey & Duffy 2001)

but are they similar to the Galactic ones ?

• In the Galaxy : ONE MORE !CPD-28°2561 (Barba & OWN survey team, 2008, in prep.)

– Spectral variations similar to HD191612

– Period not yet identified due to lack of spectra

Page 12: Yaël Nazé (Liège University),  Nolan R. Walborn (STScI),  and Maxime Spano (Geneva Observatory)

Of?p, unsolved mysteriesQuestions to be answered• Observationally :

– Are they all magnetic ? Test HD108 & the new ones !– What is the magnetic field geometry ? Monitor it !– Are small-scale variations periodic too ?

Make short-term monitoring of HD108 & HD191612 !

• Theoretically :– If LPV period = rotation period, is it possible to brake

rotation up to 55yrs, as for HD108 ?– Where does the soft X-ray emission come from ?– Why is HD148937 the only one to have a nebula ?– Where does the strong CIII emission come from ?

Page 13: Yaël Nazé (Liège University),  Nolan R. Walborn (STScI),  and Maxime Spano (Geneva Observatory)

Liege Colloquium

1996

President of the colloquium : « Andre, I am no longer sure my scenario is correct, what should I do ? »

A. Maeder : « It’s too late to cancel everything… most of the participants are seated… some of them look agressive »

Concluding remarks by the president : « you did convince me, I temporarily maintain my scenario »

Page 14: Yaël Nazé (Liège University),  Nolan R. Walborn (STScI),  and Maxime Spano (Geneva Observatory)

Astronomy is a serious affair…

but doing it in Belgium has advantages…

Rendez-vous in 2010 !