2004A&A...414..261W


Query : 2004A&A...414..261W

2004A&A...414..261W - Astronomy and Astrophysics, volume 414, 261-274 (2004/1-4)

Probing the inner halo and IVC gas through the Local Interstellar Chimney.

WELSH B.Y., SALLMEN S. and LALLEMENT R.

Abstract (from CDS):

We present an absorption study of the interstellar gas at high positive galactic latitudes in the direction close to the axis of the Local Chimney (LC), which is an extension of the rarefied local cavity that reaches out from the galactic disk to a z-distance of at least 250pc into the lower halo region. Our study includes high-resolution (R∼1.7km/s) spectral observations of the interstellar NaI and CaII absorption lines seen towards 6 early-type stars with distances ranging from 225 to 500pc contained within a radius of ∼6° along the sight-line (l=160°, b=+55°). These visible data are supplemented with far-ultraviolet absorption measurements of the interstellar sight-lines towards two hot white dwarf stars, RE J1043+490 (d=230pc) and RE J1059+512 (d=315pc), taken with the NASA Far Ultraviolet Spectroscopic Explorer (FUSE) satellite. Our observations reveal interstellar gas clouds with velocities in the -20 to -60km/s range that appear to be falling towards the galactic disk. In particular, we have detected absorption with a velocity of Vhelio~-55km/s towards two sight-lines (HD 89501 and HD 88545) that can be associated with an intermediate velocity (IV) cloud called the IV Arch. Our observations place a probable z-distance to this IVC of 275-320pc, this being much nearer than previously thought. The far UV spectra of the two hot white dwarfs show only a few (∼10) interstellar absorption lines, which is indicative of the very low density phase of the interstellar gas contained within the LC region. We have derived relative elemental abundance ratios for C, N, O, Si, Ar and Fe for these two sight-lines and find that the abundance patterns are very similar to those found for other sight-lines in the local cavity. The high ionization line of OVIλ1032 3 has been detected towards RE J1043+490 with a column density of 7x1012cm–2, which is consistent with the average space density of this ion recently found in the Local Bubble region. Finally, we (tentatively) propose a possible connection between the formation of the Gould Belt, the Local Bubble cavity, the Local Chimney and the overlying IV Arch clouds.

Abstract Copyright:

Journal keyword(s): ISM: atoms - ISM: bubbles - Galaxy: solar neighborhood

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 - 2024
#notes
1 HD 86274 * 09 58 44.4315874848 +50 07 30.561514464   6.62 6.69     B9IV 20 0
2 HD 87972 PM* 10 09 48.3831189696 +48 37 52.980355668   8.71 8.58     A3 13 0
3 HD 88545 * 10 14 19.0629999408 +56 11 44.430506880   8.13 8.10     A0 15 0
4 HD 89501 * 10 21 05.6752857312 +55 34 04.549223388 8.920 8.840 8.680     A2 21 0
5 HD 91311 * 10 33 43.7725352616 +53 29 50.608537584 6.470 6.500 6.530     A1V 38 0
6 SBSS 1040+493 WD* 10 43 11.4236321376 +49 02 23.528957028           DA1.0 52 0
7 HD 93521 * 10 48 23.5113981120 +37 34 13.083332412 5.67 6.79 7.03     O9.5IIInn 426 1
8 LB 1919 WD* 10 59 16.4293648440 +51 24 43.125083064   15.5 16.8     DA.7 56 0
9 HD 95126 * 10 59 40.2075414048 +45 47 18.888822276   8.88 8.89     A0V 31 0
10 LB 2522 Sy1 13 01 12.9250750776 +59 02 06.693816732   16.04 15.89     ~ 280 0
11 HD 121800 * 13 55 15.4510231656 +66 07 00.645739068 8.19 8.92 9.01     B5V 59 0
12 NAME IV Arch PoC ~ ~           ~ 58 1
13 NAME Local Bubble ISM ~ ~           ~ 879 0
14 NAME Local Chimney reg ~ ~           ~ 21 0
15 NAME Gould Belt PoG ~ ~           ~ 861 1

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