2009AJ....137.4526L


C.D.S. - SIMBAD4 rel 1.7 - 2019.12.06CET16:19:38

2009AJ....137.4526L - Astron. J., 137, 4526-4537 (2009/May-0)

Spatial variations in galactic H I structure on au-scales toward 3C 147 observed with the Very Long Baseline Array.

LAZIO T.J.W., BROGAN C.L., GOSS W.M. and STANIMIROVIC S.Z.

Abstract (from CDS):

This paper reports dual-epoch, Very Long Baseline Array observations of H I absorption toward 3C 147. One of these epochs (2005) represents new observations, while one (1998) represents the reprocessing of previous observations to obtain higher signal-to-noise results. Significant H I opacity and column density variations, both spatially and temporally, are observed with typical variations at the level of Δτ ~ 0.20 and in some cases as large as Δτ ~ 0.70, corresponding to column density fluctuations of order 5x1019/cm2 for an assumed 50 K spin temperature. The typical angular scale is 15 mas; while the distance to the absorbing gas is highly uncertain, the equivalent linear scale is likely to be about 10 AU. Approximately 10% of the face of the source is covered by these opacity variations, probably implying a volume filling factor for the small-scale absorbing gas of no more than about 1%. Comparing our results with earlier results toward 3C 138 (Brogan et al.), we find numerous similarities, and we conclude that small-scale absorbing gas is a ubiquitous phenomenon, albeit with a low probability of intercept on any given line of sight. Further, we compare the volumes sampled by the line of sight through the Galaxy between our two epochs and conclude that, on the basis of the motion of the Sun alone, these two volumes are likely to be substantially different. In order to place more significant constraints on the various models for the origin of these small-scale structures, more frequent sampling is required in any future observations.

Abstract Copyright:

Journal keyword(s): galaxies: individual: 3C 147 - ISM: general - ISM: structure - radio lines: ISM - techniques: interferometric

Simbad objects: 10

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Number of rows : 10

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     ~ 2439 2
2 NAME Per Arm PoG 03 30 +45.0           ~ 1201 0
3 3C 111 Sy1 04 18 21.2773655604 +38 01 35.801523843   19.75 18.05     ~ 841 1
4 NAME Per B AGN 04 37 04.37510272 +29 40 13.8184969   21.7       ~ 458 2
5 ICRF J052109.8+163822 Sy1 05 21 09.88592749 +16 38 22.0517668   19.37 18.84 18.480   ~ 726 1
6 6C 053220+503715 QSO 05 36 20.23190300 +50 38 26.2517064           ~ 12 1
7 ICRF J054236.1+495107 Sy1 05 42 36.13789843 +49 51 07.2337251   18.45 17.80 17.210   ~ 1235 1
8 NAME Gal Anticenter reg 06 17 +22.5           ~ 694 0
9 2C 553 QSO 06 27 10.1 -05 53 06           ~ 147 1
10 ICRF J182931.7+484446 Sy1 18 29 31.7812801678 +48 44 46.158815781   17.05 16.81 16.860   ~ 619 1

    Equat.    Gal    SGal    Ecl

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2019.12.06-16:19:38

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