2006A&A...454..625P


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.09CEST23:22:56

2006A&A...454..625P - Astronomy and Astrophysics, volume 454, 625-651 (2006/8-1)

Bright OB stars in the Galaxy. III. Constraints on the radial stratification of the clumping factor in hot star winds from a combined Hα, IR and radio analysis.

PULS J., MARKOVA N., SCUDERI S., STANGHELLINI C., TARANOVA O.G., BURNLEY A.W. and HOWARTH I.D.

Abstract (from CDS):

Recent results strongly challenge the canonical picture of massive star winds: various evidence indicates that currently accepted mass-loss rates, {dot}(M), may need to be revised downwards, by factors extending to one magnitude or even more. This is because the most commonly used mass-loss diagnostics are affected by ``clumping'' (small-scale density inhomogeneities), influencing our interpretation of observed spectra and fluxes. Such downward revisions would have dramatic consequences for the evolution of, and feedback from, massive stars, and thus robust determinations of the clumping properties and mass-loss rates are urgently needed. We present a first attempt concerning this objective, by means of constraining the radial stratification of the so-called clumping factor. To this end, we have analyzed a sample of 19 Galactic O-type supergiants/giants, by combining our own and archival data for Hα, IR, mm and radio fluxes, and using approximate methods, calibrated to more sophisticated models. Clumping has been included into our analysis in the ``conventional'' way, by assuming the inter-clump matter to be void. Because (almost) all our diagnostics depends on the square of density, we cannot derive absolute clumping factors, but only factors normalized to a certain minimum. This minimum was usually found to be located in the outermost, radio-emitting region, i.e., the radio mass-loss rates are the lowest ones, compared to {dot}(M) derived from Hα and the IR. The radio rates agree well with those predicted by theory, but are only upper limits, due to unknown clumping in the outer wind. Hα turned out to be a useful tool to derive the clumping properties inside r<3...5R*. Our most important result concerns a (physical) difference between denser and thinner winds: for denser winds, the innermost region is more strongly clumped than the outermost one (with a normalized clumping factor of 4.1 ±1.4), whereas thinner winds have similar clumping properties in the inner and outer regions. Our findings are compared with theoretical predictions, and the implications are discussed in detail, by assuming different scenarios regarding the still unknown clumping properties of the outer wind.

Abstract Copyright:

Journal keyword(s): infrared: stars - radio continuum: stars - stars: early-type - stars: winds, outflows - stars: mass-loss

Simbad objects: 26

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Number of rows : 26

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 3C 48 QSO 01 37 41.2995845985 +33 09 35.079126038   16.62 16.20     ~ 2497 2
2 HD 14947 s*b 02 26 46.9895793276 +58 52 33.116841083 7.83 8.44 7.98     O4.5If 237 0
3 HD 15570 Em* 02 32 49.4205362766 +61 22 42.089023028 8.40 8.80 8.11 7.41 6.86 O4If 282 0
4 * ksi Per ** 03 58 57.9022917 +35 47 27.713205 3.190 4.080 4.060 3.88 3.89 O7.5III(n)((f)) 789 0
5 * alf Cam s*b 04 54 03.0103983 +66 20 33.636467 3.47 4.34 4.29 4.18 4.18 O9Ia 635 1
6 HD 34656 Em* 05 20 43.0823042222 +37 26 19.213246169 5.87 6.77 6.76     O7.5II(f) 191 0
7 * lam Ori A Em* 05 35 08.2792540686 +09 56 02.955355445 2.17 3.48 3.47     O8III((f)) 484 0
8 * iot Ori SB* 05 35 25.9819073 -05 54 35.643537 1.45 2.53 2.77     O9IIIvar 729 0
9 * eps Ori s*b 05 36 12.81335 -01 12 06.9089 0.48 1.51 1.69 1.76 1.93 B0Ia 856 0
10 ICRF J054236.1+495107 Sy1 05 42 36.13789843 +49 51 07.2337251   18.45 17.80 17.210   ~ 1266 1
11 * zet Pup BY* 08 03 35.04754 -40 00 11.3321 0.89 1.98 2.25 2.36 2.58 O4I(n)fp 1092 1
12 3C 286 Sy1 13 31 08.2885060664 +30 30 32.960825108   17.51 17.25     ~ 3716 1
13 * ksi Sco SB* 16 04 22.134576 -11 22 23.17404     4.36     F7V 123 0
14 HD 190429A s*b 20 03 29.395 +36 01 30.53   7.20 7.09     O4If 81 0
15 HD 190429 ** 20 03 29.39885 +36 01 30.5082 5.98 6.78 6.63     O4If+O9.5II 197 0
16 HD 192639 s*b 20 14 30.4275040181 +37 21 13.815126140 6.83 7.46 7.11     O7.5Iabf 268 0
17 Schulte 12 s*b 20 32 40.9574572449 +41 14 29.276333992 16.1 14.45 11.702     B3-4Ia+ 358 0
18 Schulte 7 * 20 33 14.1095790591 +41 20 21.903381641 12.24 12.00 10.55     O3If* 129 0
19 BD+40 4227A SB* 20 33 15.0780900764 +41 18 50.478859468 10.42 10.27 8.98 8.03 6.83 O6Ib(fc)+O4.5:III:(fc) 215 0
20 Schulte 8C * 20 33 17.9821559015 +41 18 31.192311433 12.2 11.43 10.19     O4.5III(fc) 74 0
21 BD+41 3804 s*b 20 33 46.1097446575 +41 33 00.958715569 11.82 11.41 9.88     O9.7Iab 91 0
22 BD+41 3807 SB* 20 34 08.5147839926 +41 36 59.407506888 11.74 11.52 10.03     O5.5Ifc 112 0
23 * 68 Cyg SB* 21 18 27.1855667264 +43 56 45.388423736 4.05 4.99 5.00     O7.5IIIn((f)) 359 0
24 HD 207198 * 21 44 53.2790298387 +62 27 38.042162728 5.61 6.25 5.94 5.66 5.49 O8.5II 321 0
25 * 19 Cep * 22 05 08.7884887056 +62 16 47.323982519 4.36 5.19 5.11 4.95 4.92 O9Ib 362 0
26 * lam Cep s*b 22 11 30.5750839949 +59 24 52.147736074 4.55 5.29 5.05 4.77 4.62 O6.5I(n)fp 646 1

    Equat.    Gal    SGal    Ecl

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2020.07.09-23:22:56

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