view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the velocity field of the nearby interstellar hydrogen. Helfer, H. L. Abstract This is a progress report upon the analysis of the 21-cm survey for (b >200, undertaken at the Department of Terrestrial Magnetism, Carnegie Institute of Washington, and reported upon previously (Erickson, HeIfer and Tatel 1959). Rough agreement between Shain's local magnetic pole of the Galaxy (Shain 1957) and the crudely defined pole of the high-latitude interstellar hydrogen suggests that the distribution of the interstellar gas is quite dependent upon the local magnetic field and that the possibility that the velocity-distance relation for the gas is different from that of the stars cannot be ignored. As reported previously, the high latitude 21-cm line profiles give evidence of significant large-scale structure. Accordingly, a solution for the velocity-distance relation of the nearby gas was attempted. Including only first order terms one may write for the radial velocity: V(1, b) = a + sR, where R is the distance and s = K + cos2 b (C + B1 sin 21 + B2 cos 21) + (A3 sin 1 + A2 cos 1) sin 2b, a = W1 cos 1 cos b + W2 sin 1 cos b + W3 sin b. Using subjective estimates of the peak or center of line-profile velocities, solutions for the relative ratios, K: C: B1: B2: A1 : A2, were determined from the seven available values of (1, b) for which V(1, b) + V(1 + 1800, -b) = 0. The preliminary values are: 1.000, -0.820, -0.311,0.182, +0.743, -0.322, in the order given above. The figures quoted are probably already influenced slightly by the occurrence of second order terms, their influence being evident in the observations taken at b = ~ 200. The values of W1, W2, W3, determined from the value of V(1, b) - V(1 + 1800, -b) at the aforementioned zero points, are found to be 1.24 km/sec, 2.62 km/sec, - I .6o km/sec, respectively, but these values are quite crude. If accepted literally, this would suggest that the circular velocity of the local gas is about 3 km/sec faster than that of the stars. The coordinate system used is that defined by the Lund Tables (Ohlsson, Reiz and Torgard 1956) with galactic center at 1 3270, b - 10 and the velocity scale origin is the local stellar standard of rest, as given by the Lund Tables (MacRae and Westerhout 1956). This work was supported in part by the U.S. Air Force under Contract No. AF49(638)-52. REFERENCES Erickson, W. C., Heifer, H. L. and Tatel, H. E. 1959, URSI-IA U Radio Astron. Symp. Paris 1958, in press. MacRae, D. A. and Westerhout, G. 1956, Tables for the Reduction of Velocities to the Local Standard of Rest, Lund Observatory. Ohisson, J., Reiz, A. and Torg~d, I. 1956, Tables for the Conversion of Galactic into Equatorial Coordinates, Lund Observatory. Shain, G. A. 1957, Russian A. J. 34, 3. Department of Physics and Astronomy, University of Rochester, Rochester, N. V. Publication: The Astronomical Journal Pub Date: 1959 DOI: 10.1086/107982 Bibcode: 1959AJ.....64Q.128H full text sources ADS |