def calc_gcen_coords(glong, glat, dist, R0=__R0,
Zsun=__Zsun, roll=__roll, use_Zsunroll=True):
"""
Calculate galactocentric Cartesian coordinates from
galactic longitudes, latitudes, and distances from the Sun.
Parameters:
glong, glat :: scalar or array of scalars
Galactic longitude and latitude (deg)
dist :: scalar or array of scalars
line-of-sight distance (kpc)
R0 :: scalar or array of scalars (optional)
Galactocentric radius of the Sun
Zsun :: scalar (optional)
Height of Sun above galactic midplane (pc)
roll :: scalar (optional)
Roll angle relative to b=0 (deg)
use_Zsunroll :: boolean (optional)
If True, include Zsun and roll into calculation
Returns: x, y, Rgal, cos_az, sin_az
x, y :: scalars or arrays of scalars
Galactocentric Cartesian positions (kpc). Sun is on -x-axis.
Rgal :: scalar or array of scalars
Galactocentric cylindrical radius (kpc)
cos_az, sin_az :: scalar or array of scalars
Cosine and sine of Galactocentric azimuth (rad)
"""
glong, glat, dist = np.atleast_1d(glong, glat, dist)
if np.shape(glong) != np.shape(dist):
glong = np.array([glong, ] * len(dist))
Rgal = kd_utils.calc_Rgal(
glong, glat, dist, R0=R0,
Zsun=Zsun, roll=roll, use_Zsunroll=use_Zsunroll)
Rgal[Rgal < 1.0e-6] = 1.0e-6 # Catch small Rgal
az = kd_utils.calc_az(
glong, glat, dist, R0=R0,
Zsun=Zsun, roll=roll, use_Zsunroll=use_Zsunroll)
cos_az = np.cos(np.deg2rad(az))
sin_az = np.sin(np.deg2rad(az))
x = Rgal * -cos_az
y = Rgal * sin_az
return x, y, Rgal, cos_az, sin_az
def calc_vlsr(glong,
glat,
dist,
R0=__R0,
Usun=__Usun,
Vsun=__Vsun,
Wsun=__Wsun,
Upec=__Upec,
Vpec=__Vpec,
a2=__a2,
a3=__a3,
Zsun=__Zsun,
roll=__roll,
peculiar=False):
"""
Return the IAU-LSR velocity at a given Galactic longitude and
line-of-sight distance.
Parameters:
glong, glat :: scalars or arrays of scalars
Galactic longitude and latitude (deg).
dist :: scalar or array of scalars
line-of-sight distance (kpc).
R0 :: scalar (optional)
Solar Galactocentric radius (kpc)
Usun, Vsun, Wsun, Upec, Vpec, a2, a3 :: scalars (optional)
Reid+2019 rotation curve parameters
Zsun :: scalar (optional)
Height of sun above Galactic midplane (pc)
roll :: scalar (optional)
Roll of Galactic midplane relative to b=0 (deg)
peculiar :: boolean (optional)
If True, include HMSFR peculiar motion component
Returns: vlsr
vlsr :: scalar or array of scalars
LSR velocity (km/s).
"""
input_scalar = np.isscalar(glong) and np.isscalar(glat) and np.isscalar(
dist)
glong, glat, dist = np.atleast_1d(glong, glat, dist)
cos_glong = np.cos(np.deg2rad(glong))
sin_glong = np.sin(np.deg2rad(glong))
cos_glat = np.cos(np.deg2rad(glat))
sin_glat = np.sin(np.deg2rad(glat))
#
# Convert distance to Galactocentric, catch small Rgal
#
Rgal = kd_utils.calc_Rgal(glong, glat, dist, R0=R0)
Rgal[Rgal < 1.e-6] = 1.e-6
az = kd_utils.calc_az(glong, glat, dist, R0=R0)
cos_az = np.cos(np.deg2rad(az))
sin_az = np.sin(np.deg2rad(az))
#
# Rotation curve circular velocity
#
theta = calc_theta(Rgal, a2=a2, a3=a3, R0=R0)
theta0 = calc_theta(R0, a2=a2, a3=a3, R0=R0)
#
# Add HMSFR peculiar motion
#
if peculiar:
vR = -Upec
vAz = theta + Vpec
vZ = 0.0
else:
vR = 0.0
vAz = theta
vZ = 0.0
vXg = -vR * cos_az + vAz * sin_az
vYg = vR * sin_az + vAz * cos_az
vZg = vZ
#
# Convert to barycentric
#
X = dist * cos_glat * cos_glong
Y = dist * cos_glat * sin_glong
Z = dist * sin_glat
# useful constants
sin_tilt = Zsun / 1000. / R0
cos_tilt = np.cos(np.arcsin(sin_tilt))
sin_roll = np.sin(np.deg2rad(roll))
cos_roll = np.cos(np.deg2rad(roll))
# solar peculiar motion
vXg = vXg - Usun
vYg = vYg - theta0 - Vsun
vZg = vZg - Wsun
# correct tilt and roll of Galactic midplane
vXg1 = vXg * cos_tilt - vZg * sin_tilt
vYg1 = vYg
vZg1 = vXg * sin_tilt + vZg * cos_tilt
vXh = vXg1
vYh = vYg1 * cos_roll + vZg1 * sin_roll
vZh = -vYg1 * sin_roll + vZg1 * cos_roll
vbary = (X * vXh + Y * vYh + Z * vZh) / dist
#
# Convert to IAU-LSR
#
vlsr = vbary + (__Ustd * cos_glong +
__Vstd * sin_glong) * cos_glat + __Wstd * sin_glat
if input_scalar:
return vlsr[0]
return vlsr