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The distance to Complex M and the Intermediate Velocity Arch
The Intermediate Velocity Arch is an association of Hi clouds lyingwithin the broad limits l~110 deg-210 deg,b~50 deg-80 deg. We usehigh-resolution optical, and single-dish 21-cm, observations of 10early-type halo star sightlines in this region to establish distancelimits (0.4<=z<=3.5kpc) for seven IVCs that are part of the Arch.We re-examine a previous determination of upper and lower distancelimits on the IVC Complex M using the closely aligned halo starsBD+382182 and HD93521. Our Hi spectra show no evidence of emission fromComplex M, leading us to conclude that, while an upper distance limit ofz<=3.5 kpc may be established, no useful lower distance determinationcan be made. Our new Hi observations allow new limits to be establishedon the metallicity of Complex M, and show C, O and Si variations withrespect to solar abundances in the range +/-0.3 dex.
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Osservazione e dati astrometrici
| Costellazione: | Orsa Maggiore |
| Ascensione retta: | 11h01m40.87s |
| Declinazione: | +49°36'34.0" |
| Magnitudine apparente: | 9.062 |
| Moto proprio RA: | -11 |
| Moto proprio Dec: | -1.8 |
| B-T magnitude: | 10.684 |
| V-T magnitude: | 9.196 |
Cataloghi e designazioni:
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