| dc.description.abstract | Stellar rotation is one of the most important parameters in astrophysics and its effects
are observed in all evolutionary stage, since the beginning. This present work shows an
analysis of the rotation from photometric measures along the Hertzsprung-Russell diagram
(HR diagram), for stars in different evolutionary stages, such as: main sequence, subgiants,
giants, bright giants and supergiants Ib. We use stellar evolution models with rotation, in
which the metallicity are z = 0, 002 and z = 0, 014, presented respectively by Georgy et al.
(2013b) and Ekström et al. (2012). Through the measurement of angular rotation velocities,
Ω, presented in the models, we estimate the rotation period for each evolutionary track (with
masses ranging from 0, 8M < M ≤ 20M ) and consequently we determine the rotation
isoperiodic lines using the interpolation technique cubic spline for a effective temperature
region 3.500 < Tef ≤ 10.500 K and luminosity −1, 0 < Log (L/L ) ≤ 5, 5. The interpolation
technique was utilized to the mean values ±5% of the desired measurements, which are
5, 15, 25, 50 and 100 days. Combining isoperiods to the distribution of rotation period
values of our samples, we have observed a significant congruence between the theoretical
data and the observed data, for stars with rotation period determined by photometric
modulation, as well as periods estimated from v sen i. However, some stars may present
a rotational behavior that diverges from the rotation isoperiods. Furthermore, our results
show that the discontinuity in the rotation period happens gradually and in every luminosity
class, in both the vertical direction (which depends on the stellar luminosity and mass) and
the horizontal direction (which depends on the effective temperature) in the HR diagram.
The discontinuity in the rotation period is more evident in stars which the periods were
estimated from the projected rotation velocity. Such effect happens more clearly between
masses 0, 8M < M ≤ 1, 35M , around 5.500 K, for stars with [F e/H] = −1, 0 ± 0, 5 dex.
On the other side, stars with [F e/H] = 0, 0 ± 0, 5 dex that present discontinuity in the
rotation period have masses between 0, 9M < M ≤ 2M in the Tef ≤ 6.200 K region. | |
