IANIGLA   20881
INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
artículos
Título:
A study of the B6-9 and A giants
Autor/es:
RICHARD L. BRANHAM, JR.
Revista:
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Editorial:
WILEY-BLACKWELL PUBLISHING, INC
Referencias:
Año: 2009 vol. 396 p. 1473 - 1473
ISSN:
0035-8711
Resumen:
1 ABSTRACT To study the kinematics of the B6-9 and A giant stars (luminosity class III) use is made of proper motions taken from van Leeuwen’s new reduction of the Hipparcos catalog. 36% of the B6-9 stars appear to pertain to the Gould belt, and were excluded from the study. No A star, however, seems to be associated with the Gould belt. 597 B6-9 giants, of which 147 have radial velocities, and 692 A giants, of which 144 have radial velocities, were used in the final study. Semi-definite programming solves, using least squares, for the kinematical parameters such as the Oort constants and simultaneously for the coefficients of the velocity ellipsoid, reduced with the robust L1 norm. The condition that both the solution for the solar velocity calculated from the kinematical parameters and from the velocity ellipsoid calculation be the same is enforced. The results obtained seem reasonable. For the B6-9 giants: solar velocity of 16.45±0.40 km s−1; Oort’s constant’s, in units of km s−1 kpc−1, A = 11.77±1.66 and B = −9.05±1.38, implying a rotational velocity of 176.95±9.62 km s−1 if we take the distance to the Galactic center as 8.5±1.1 kpc; velocity dispersions, in units of km s−1, of: x = 39.25±3.29, y = 19.83±1.16, z = 14.07±0.85 with a vertex deviation of -19.44±0.14.. For the A giants the corresponding values are: solar velocity 13.95±0.58 km s−1; Oort’s constant’s of A = 11.48 ± 5.45 andHipparcos catalog. 36% of the B6-9 stars appear to pertain to the Gould belt, and were excluded from the study. No A star, however, seems to be associated with the Gould belt. 597 B6-9 giants, of which 147 have radial velocities, and 692 A giants, of which 144 have radial velocities, were used in the final study. Semi-definite programming solves, using least squares, for the kinematical parameters such as the Oort constants and simultaneously for the coefficients of the velocity ellipsoid, reduced with the robust L1 norm. The condition that both the solution for the solar velocity calculated from the kinematical parameters and from the velocity ellipsoid calculation be the same is enforced. The results obtained seem reasonable. For the B6-9 giants: solar velocity of 16.45±0.40 km s−1; Oort’s constant’s, in units of km s−1 kpc−1, A = 11.77±1.66 and B = −9.05±1.38, implying a rotational velocity of 176.95±9.62 km s−1 if we take the distance to the Galactic center as 8.5±1.1 kpc; velocity dispersions, in units of km s−1, of: x = 39.25±3.29, y = 19.83±1.16, z = 14.07±0.85 with a vertex deviation of -19.44±0.14.. For the A giants the corresponding values are: solar velocity 13.95±0.58 km s−1; Oort’s constant’s of A = 11.48 ± 5.45 and1 norm. The condition that both the solution for the solar velocity calculated from the kinematical parameters and from the velocity ellipsoid calculation be the same is enforced. The results obtained seem reasonable. For the B6-9 giants: solar velocity of 16.45±0.40 km s−1; Oort’s constant’s, in units of km s−1 kpc−1, A = 11.77±1.66 and B = −9.05±1.38, implying a rotational velocity of 176.95±9.62 km s−1 if we take the distance to the Galactic center as 8.5±1.1 kpc; velocity dispersions, in units of km s−1, of: x = 39.25±3.29, y = 19.83±1.16, z = 14.07±0.85 with a vertex deviation of -19.44±0.14.. For the A giants the corresponding values are: solar velocity 13.95±0.58 km s−1; Oort’s constant’s of A = 11.48 ± 5.45 and±0.40 km s−1; Oort’s constant’s, in units of km s−1 kpc−1, A = 11.77±1.66 and B = −9.05±1.38, implying a rotational velocity of 176.95±9.62 km s−1 if we take the distance to the Galactic center as 8.5±1.1 kpc; velocity dispersions, in units of km s−1, of: x = 39.25±3.29, y = 19.83±1.16, z = 14.07±0.85 with a vertex deviation of -19.44±0.14.. For the A giants the corresponding values are: solar velocity 13.95±0.58 km s−1; Oort’s constant’s of A = 11.48 ± 5.45 and−1 kpc−1, A = 11.77±1.66 and B = −9.05±1.38, implying a rotational velocity of 176.95±9.62 km s−1 if we take the distance to the Galactic center as 8.5±1.1 kpc; velocity dispersions, in units of km s−1, of: x = 39.25±3.29, y = 19.83±1.16, z = 14.07±0.85 with a vertex deviation of -19.44±0.14.. For the A giants the corresponding values are: solar velocity 13.95±0.58 km s−1; Oort’s constant’s of A = 11.48 ± 5.45 and±9.62 km s−1 if we take the distance to the Galactic center as 8.5±1.1 kpc; velocity dispersions, in units of km s−1, of: x = 39.25±3.29, y = 19.83±1.16, z = 14.07±0.85 with a vertex deviation of -19.44±0.14.. For the A giants the corresponding values are: solar velocity 13.95±0.58 km s−1; Oort’s constant’s of A = 11.48 ± 5.45 and±1.1 kpc; velocity dispersions, in units of km s−1, of: x = 39.25±3.29, y = 19.83±1.16, z = 14.07±0.85 with a vertex deviation of -19.44±0.14.. For the A giants the corresponding values are: solar velocity 13.95±0.58 km s−1; Oort’s constant’s of A = 11.48 ± 5.45 and.25±3.29, y = 19.83±1.16, z = 14.07±0.85 with a vertex deviation of -19.44±0.14.. For the A giants the corresponding values are: solar velocity 13.95±0.58 km s−
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