2011MNRAS.415.1105S -
Mon. Not. R. Astron. Soc., 415, 1105-1118 (2011/August-1)
Distance limits to intermediate- and high-velocity clouds.
SMOKER J.V., FOX A.J. and KEENAN F.P.
Abstract (from CDS):
We present optical spectra of 403 stars and quasi-stellar objects in order to obtain distance limits towards intermediate- and high-velocity clouds (IHVCs), including new Fibre-fed Extended Range Optical Spectrograph (FEROS) observations plus archival ELODIE, FEROS, High Resolution Echelle Spectrometer (HIRES) and Ultraviolet and Visual Echelle Spectrograph (UVES) data. The non-detection of Ca II K interstellar (IS) absorption at a velocity of -130 to -60 km/s towards HDE 248894 (
d∼ 3 kpc) and HDE 256725 (
d∼ 8 kpc) in data at signal-to-noise ratio (S/N) > 450 provides a new firm lower distance limit of 8 kpc for the anti-centre shell HVC. Similarly, the non-detection of Ca II K IS absorption towards HD 86248 at S/N ∼ 500 places a lower distance limit of 7.6 kpc for Complex EP, unsurprising since this feature is probably related to the Magellanic System. The lack of detection of Na I D at S/N = 35 towards Mrk 595 puts an improved upper limit for the Na I column density of log (
NNaD<) 10.95/cm2 towards this part of the Cohen Stream where Ca II was detected by Wakker et al. Absorption at ∼-40 km/s is detected in Na I D towards the Galactic star PG 0039+049 at S/N = 75, placing a firm upper distance limit of 1 kpc for the intermediate-velocity cloud south (IVS), where a tentative detection had previously been obtained by Centurión et al. Ca II K and Na I D absorption is detected at -53 km/s towards HD 93521, which confirms the upper distance limit of 2.4 kpc for part of the IV arch complex obtained using the
International Ultraviolet Explorer (
IUE) data by Danly. Towards HD 216411 in Complex H a non-detection in Na D towards gas with log({img}) = 20.69/cm2 puts a lower distance limit of 6.6 kpc towards this HVC complex. Additionally, Na I D absorption is detected at -43.7 km/s in the star HD 218915 at a distance of 5.0 kpc in gas in the same region of the sky as Complex H. Finally, the Na I/Ca II and Ca II/H I ratios of the current sample are found to lie in the range observed for previous studies of IHVCs.
Based on European Southern Observatory (ESO) programme IDs 078.C-0493(A) and 171.D-0237(B). Analysis of
MOST light curves of five young stars in Taurus-Auriga and Lupus 3 star-forming regions
Abstract Copyright:
2011 The Authors Monthly Notices of the Royal Astronomical Society2011 RAS
Journal keyword(s):
stars: early-type - ISM: abundances - ISM: clouds - ISM: general - ISM: structure
VizieR on-line data:
<Available at CDS (J/MNRAS/415/1105): table3.dat>
Simbad objects:
392
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