2012A&A...537A..51W


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.09CET09:13:20

2012A&A...537A..51W - Astronomy and Astrophysics, volume 537A, 51-51 (2012/1-1)

Ultraviolet absorption observations of intermediate-velocity cloud gas detected towards the M 15 globular cluster.

WELSH B.Y., WHEATLEY J. and LALLEMENT R.

Abstract (from CDS):

We present medium resolution ultraviolet interstellar absorption measurements recorded with the HST-COS and FUSE spectrographs towards two post-AGB stars (K559 & K648) located within the M 15 globular cluster (l∼65°, b~-27°). By sampling interstellar gas over the 10.4kpc sight-line towards M 15 we wish to reveal spectral features that are associated with absorption due to the foreground g1 intermediate velocity cloud (IVC), whose distance has previously been constrained to lie between 1.8-3.8kpc. Inspection of the UV line profiles recorded towards both stars have revealed measurable IVC absorption at Vlsr~+61.5±5km/s in the profiles of the CI, CII, CII*, CIV, NI, NII, OI, OVI, AlII, SiII, SiIII, SiIV, PII, SII, FeII, FeIII and NiII ions. Line-profile fitting to the IVC absorption features has resulted in column density determinations for the low and high ions. The best-fit column density values for the various ions have near identical values along both sight-lines, such that our UV data does not reveal the significant small-scale structure that has been reported previously for the g1 cloud. The observed column density ratios of the CIV, SiIV, OVI and NV IV components are consistent with what may be expected from turbulent mixing layers, shock ionization or halo SNR models, although no one model can predict all of the observed ratios. We derive sub-solar metallicity values of [O/H]=-1.22±0.44 and [N/H]=-1.21±0.38 for the neutral IVC gas, and also the IV components of C, Si, Al, Ni and Fe mainly possess less than solar abundance ratios relative to that of N. A possible origin for the g1 IVC is that of a low metallicity cloud that has been accreted towards our galaxy, has passed through the disk and is now moving away from the galactic plane.

Abstract Copyright:

Journal keyword(s): ISM: clouds - ISM: abundances - galaxies: halos

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 HVC 291.2-41.2+80 ? 02 59 -73.0           ~ 5 0
2 NAME Magellanic Bridge HI 03 11 -77.5           ~ 355 1
3 NAME HVC Complex M HVC 10 48.2 +48 00           ~ 73 0
4 Mrk 421 BLL 11 04 27.3139210166 +38 12 31.798324828   13.50 12.90 8.31   ~ 2428 1
5 M 5 GlC 15 18 33.22 +02 04 51.7   7.34 5.95     ~ 1806 0
6 NAME HVC Complex C HVC 16 34.8 +63 07           ~ 230 1
7 M 13 GlC 16 41 41.634 +36 27 40.75     5.8     ~ 2036 0
8 M 55 GlC 19 39 59.71 -30 57 53.1     6.49     ~ 776 0
9 NAME Gal Center Positive HVC 20 51.2 +01 41           ~ 76 1
10 NGC 7078 559 * 21 29 58.23 +12 11 42.0   14.19 14.98     ~ 22 1
11 M 15 GlC 21 29 58.33 +12 10 01.2   3       ~ 2943 0
12 PN G065.0-27.3 PN 21 29 59.38 +12 10 27.5   13.39 14.06     sdO 277 0
13 NGC 7078 649 * 21 29 59.62 +12 10 41.8           ~ 3 0
14 NAME IV Arch PoC ~ ~           ~ 52 1
15 NAME PP Arch PoC ~ ~           ~ 8 0

    Equat.    Gal    SGal    Ecl

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2021.03.09-09:13:20

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