1999AJ....118.2394G


C.D.S. - SIMBAD4 rel 1.7 - 2021.04.16CEST11:33:39

1999AJ....118.2394G - Astron. J., 118, 2394-2408 (1999/November-0)

A large H I shell surrounding the Wolf-Rayet star HD 191765.

GERVAIS S. and ST-LOUIS N.

Abstract (from CDS):

We have surveyed a 2°.6x2°.6 field centered on the Wolf-Rayet (W-R) star HD 191765 (=WR 134) in the H I 21 cm line and in the 1420 and 408 MHz radio continuum, using the Synthesis Telescope of the Dominion Radio Astrophysical Observatory, to search for direct evidence of the interaction between the W-R star wind and the interstellar medium. An arc-shaped structure is present in the 1420 MHz continuum image, which perfectly matches the optical nebula Anon (MR 100). That this gas is not visible on our 408 MHz map hints at the thermal nature of the source. This ionized gas could be associated with luminous blue variable or red supergiant ejecta swept up by the W-R wind and photoionized by the strong ultraviolet flux from the star. However, this suggestion needs to be confirmed by clear CNO enrichment measurements in the northwest region of the nebula.

Our H I maps reveal the existence of a nearly complete shell at a velocity of vsys=-11.44 km.s–1 (Rs~20.9 pc, vexp~9.9 km.s–1, MHI~1830 M), which, mainly for morphological reasons, we associate with HD 191765 (although a contribution from the nearby W-R star HD 192103 cannot be totally excluded). The dynamical age of this bubble (∼1.3x106 yr) suggests that it was mainly blown during the main-sequence progenitor O-star phase. The kinematic distance corresponding to a local standard of rest velocity of -11 km.s–1 is approximately 5 kpc, which is incompatible with the association distance of HD 191765 of 2.1 kpc. Therefore, we conclude that the H I bubble we have detected was blown in gas already in movement with respect to normal Galactic rotation for this region. There is independent evidence that gas at this velocity is present in this line of sight. Recent Hipparcos data analyzed by Moffat et al. give a supersonic proper motion for HD 191765 (projected velocity ∼52 km.s–1 at a position angle on the sky of P.A.=-38°). This velocity vector points away from a position very close to the center of the H I bubble, which strengthens the hypothesis of a physical link with the W-R star. The supersonic velocity of the star with respect to the interstellar medium might have generated some compression of the interstellar medium in the southwest region, rendering the Hα gas brighter in that direction with respect to the surroundings.


Abstract Copyright:

Journal keyword(s): ISM: Bubbles - ISM: individual (Anonymous MR 100) - Stars: Circumstellar Matter - Stars: Wolf-Rayet - stars: individual (WR 134 = HD 191765)

Simbad objects: 15

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Number of rows : 15

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 HD 50896 WR* 06 54 13.0440847499 -23 55 42.020318514 5.74 6.63 6.91 7.74   WN4b 749 0
2 HD 56925 WR* 07 18 29.1313276537 -13 13 01.513156589 11.21 11.74 11.56 11.40   WN4b 162 0
3 NGC 2359 HII 07 18 30.000 -13 13 36.00           ~ 161 0
4 NAME Cyg A Sy2 19 59 28.35645829 +40 44 02.0966496   16.22 15.10     ~ 2163 2
5 Ass Cyg OB 3 As* 20 07 +35.9           ~ 172 0
6 NAME Bubble around HD 191765 HI 20 10 +36.1           ~ 7 0
7 HD 191765 WR* 20 10 14.1929815789 +36 10 35.069005168 7.64 8.08 8.08     WN6-s 428 0
8 HD 228199 * 20 11 27.2644566068 +36 29 56.854384259   9.41 9.34     B0.5:V 31 0
9 HD 192103 WR* 20 11 53.5274946554 +36 11 50.523501826 7.77 8.13 8.11     WC8+OB: 325 0
10 HD 192163 WR* 20 12 06.5420067895 +38 21 17.783840972 7.12 7.49 7.50     WN6(h)-s 525 0
11 NGC 6888 ISM 20 12 07 +38 21.3   7.44       WN6b(h) 262 1
12 SNR G073.9+00.9 SNR 20 14 15 +36 12.0           ~ 66 0
13 Ass Cyg OB 1 As* 20 17.8 +37 38           ~ 254 1
14 NAME Cyg X Cld 20 28 41 +41 10.2           ~ 648 1
15 NAME Cyg Complex reg 20 32 +45.0           ~ 535 0

    Equat.    Gal    SGal    Ecl

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