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 - 1486
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 Leeuwens
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; Oorts constants, 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; Oorts constants 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; Oorts constants, 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; Oorts constants 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; Oorts constants, 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; Oorts constants of A = 11.48 ± 5.45 and±0.40 km s−1; Oorts constants, 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; Oorts constants 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; Oorts constants 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; Oorts constants 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; Oorts constants 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−