Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Rotating halo traced by the K giant stars from LAMOST and Gaia   With the help of Gaia DR2, we are able to obtain the full 6-D phase space
information for stars from LAMOST DR5. With high precision of position,
velocity, and metallicity, the rotation of the local stellar halo is presented
using the K giant stars with [Fe/H]$<-1$ dex within 4 kpc from the Sun. By
fitting the rotational velocity distribution with three Gaussian components,
stellar halo, disk, and a counter-rotating hot population, we find that the
local halo progradely rotates with $V_T=+27^{+4}_{-5}$ km s$^{-1}$ providing
the local standard of rest velocity of $V_{LSR}=232$ km s$^{-1}$. Meanwhile, we
obtain the dispersion of rotational velocity is $\sigma_{T}=72^{+4}_{-4}$ km
s$^{-1}$. Although the rotational velocity strongly depends on the choice of
$V_{LSR}$, the trend of prograde rotation is substantial even when $V_{LSR}$ is
set at as low as 220 km s$^{-1}$. Moreover, we derive the rotation for
subsamples with different metallicities and find that the rotational velocity
is essentially not correlated with [Fe/H]. This may hint a secular evolution
origin of the prograde rotation. It shows that the metallicity of the
progradely rotating halo is peaked within -1.9$<$[Fe/H]$<$-1.6 without
considering the selection effect. We also find a small fraction of
counter-rotating stars with larger dispersion and lower metallicity. Finally,
the disk component rotates with $V_T=+182^{+6}_{-6}$ km s$^{-1}$ and
$\sigma_T=45^{+3}_{-3}$ km s$^{-1}$, which is quite consistent with the
metal-weak thick disk population.

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The categories of this paper are: hep-ph
20
The categories of this paper are: acc-phys
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
17
The categories of this paper are: q-fin
12
The categories of this paper are: nucl-th
26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int
10
The categories of this paper are: q-bio
36
The categories of this paper are: cmp-lg
24
The categories of this paper are: dg-ga
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The categories of this paper are: cond-mat