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The DDO IVC Distance Project: Survey Description and the Distance to G139.6+47.6
We present a detailed analysis of the distance determination for oneintermediate-velocity cloud (IVC, G139.6+47.6) from the ongoing DDO IVCDistance Project. Stars along the line of sight to G139.6+47.6 areexamined for the presence of sodium absorption attributable to thecloud, and the distance bracket is established by astrometric andspectroscopic parallax measurements of demonstrated foreground andbackground stars. We detail our strategy regarding target selection,observational setup, and analysis of the data, including a discussion ofwavelength calibration and sky subtraction uncertainties. We find adistance estimate of 129+/-10 pc for the lower limit and257+211-33 pc for the upper limit. Given the highnumber of stars showing absorption due to this IVC, we also discuss thesmall-scale covering factor of the cloud and the likely significance ofnondetections for subsequent observations of this and other similarIVCs. Distance measurements of the remaining targets in the DDO IVCproject will be detailed in a companion paper.
| A universal formula for determining the stellar mass loss rate
The quiet outflow of stellar mass, which occurs as stellar wind, isconsidered. Mass loss rates (M) for 400 stars were used to derive aformula expressing M as a function of four stellar parameters: L,T(eff), Y, and Z.
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Besorolás csoportokba:
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Pozíciós és asztrometriai adatok
| Csillagkép: | Nagy Medve |
| Rektaszcenzió: | 10h52m32.33s |
| Deklináció: | +64°46'30.7" |
| Vizuális fényesség: | 8.567 |
| Távolság: | 164.745 parszek |
| RA sajátmozgás: | 11.6 |
| Dec sajátmozgás: | 8 |
| B-T magnitude: | 8.905 |
| V-T magnitude: | 8.595 |
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