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The magnetic dynamo mechanism of giant stars remains an open question, which can be explored by investigating their activity–rotation relations with multiple proxies. By using the data from the LAMOST and Galaxy Evolution Explorer surveys, we carried out a comprehensive study of activity–rotation relations of evolved stars based on Ca ii H and K lines, H α lines, and near-ultraviolet (NUV) emissions. Our results show that evolved stars and dwarfs obey a similar power law in the unsaturated region of the activity–rotation relation, indicating a common dynamo mechanism in both giants and dwarfs. There is no clear difference in the activity levels between red giant branch stars and red clump stars, nor between single giants and those in binaries. Additionally, our results show that the NUV activity levels of giants are comparable to those of G- and K-type dwarfs and are higher than those of M dwarfs. [ABSTRACT FROM AUTHOR]

The magnetic dynamo mechanism of giant stars remains an open question, which can be explored by investigating their activity–rotation relations with multiple proxies. By using the data from the LAMOST and Galaxy Evolution Explorer surveys, we carried out a comprehensive study of activity–rotation relations of evolved stars based on Ca ii H and K lines, H α lines, and near-ultraviolet (NUV) emissions. Our results show that evolved stars and dwarfs obey a similar power law in the unsaturated region of the activity–rotation relation, indicating a common dynamo mechanism in both giants and dwarfs. There is no clear difference in the activity levels between red giant branch stars and red clump stars, nor between single giants and those in binaries. Additionally, our results show that the NUV activity levels of giants are comparable to those of G- and K-type dwarfs and are higher than those of M dwarfs.

We analyze the three-dimensional kinematics of about 82 000 Tycho-2 stars belonging to the red giant clump (RGC). First, based on all of the currently available data, we have determined new, most probable components of the residual rotation vector of the optical realization of the ICRS/HIPPARCOS system relative to an inertial frame of reference, ( ω, ω, ω) = (−0.11, 0.24, −0.52) ± (0.14, 0.10, 0.16) mas yr. The stellar proper motions in the form µ cos δ have then be corrected by applying the correction ω = −0.52 mas yr. We show that, apart from their involvement in the general Galactic rotation described by the Oort constants A = 15.82 ± 0.21 km s kpc and B = −10.87 ± 0.15 km s kpc, the RGC stars have kinematic peculiarities in the Galactic yz plane related to the kinematics of the warped stellar-gaseous Galactic disk. We show that the parameters of the linear Ogorodnikov-Milne model that describe the kinematics of RGC stars in the zx plane do not differ significantly from zero. The situation in the yz plane is different. For example, the component of the solid-body rotation vector of the local solar neighborhood around the Galactic x axis is M = −2.6 ± 0.2 km s kpc. Two parameters of the deformation tensor in this plane, namely M = 1.0 ± 0.2 km s kpc and M − M = −1.3 ± 0.4 km s kpc, also differ significantly from zero. On the whole, the kinematics of the warped stellar-gaseous Galactic disk in the local solar neighborhood can be described as a rotation around the Galactic x axis (close to the line of nodes of this structure) with an angular velocity −3.1 ± 0.5 km s kpc ≤ Ω ≤ −4.4 ± 0.5 km s kpc. [ABSTRACT FROM AUTHOR]