Observations of interstellar Na I in the spectra of 93 stars within 315 pc from the Sun show that it lies in a tunnel of gas moving away from Scorpio-Centaurus and is surrounded by gas moving toward the Galactic center.
Gas approaches the Sun from Scorpio-Centaurus expanding from (r, l, b)=(160 pc, 313°7, +28°2) with LSR velocity 15.3 km s−1. The radius of this shell is 153 pc.
We identify these clouds:
D: velocity vector (υ
d, l
d, b
d)=(+7.2 km s−1, 305°1, −13°5), above and below the Galactic plane (GP) in the range of Galactic longitudes 357°–55°.
C: velocity vector (υ
c, l
c, b
c)=(+11.5 km s−1, 349°0, −35°2), above and below the GP in the range 30°≤l≤110°.
M: velocity vector (υ
m, l
m, b
m)=(+21.9 km s−1, 34°2, +1°5), above and below the GP in the range 100°≤l≤130°.
P: velocity vector (υ
p, l
p, b
p)=(+13.8 km s−1, 244°9, +5°4), above and below the GP from l~120° to the limit of our data at l~210°.
E: velocity vector (υ
e, l
e, b
e)=(+16.8 km s−1, 208°4, +6°2) in the range 160°≤l≤185° and −10°≤b≤–35°.
A: velocity vector (υ
a, l
a, b
a)=(+12.9 km s−1, 73°6, −5°6) towards the Galactic anti-center, below the GP.
I: velocity vector (υ
i, l
i, b
i)=(+37.7 km s−1, 132°8, −64°3) towards the Galactic anti-center, above the GP.