Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evidence for abnormal H$\alpha$ variability during near-transit
  observations of HD 189733 b   Changes in levels of stellar activity can mimic absorption signatures in
transmission spectra from circumplanetary material. The frequency and magnitude
of these changes is thus important to understand in order to attribute any
particular signal to the circumplanetary environment. We present short-cadence,
high-resolution out-of-transit H$\alpha$ spectra for the hot Jupiter host HD
189733 in order to establish the frequency and magnitude of intrinsic stellar
variations in the H$\alpha$ line core. We find that changes in the line core
strength similar to those observed immediately pre- and post-transit in two
independent data sets are uncommon. This suggests that the observed
near-transit signatures are either due to absorbing circumplanetary material or
occur preferentially in time very near planetary transits. In either case, the
evidence for abnormal H$\alpha$ variability is strengthened, although the
short-cadence out-of-transit data do not argue for circumplanetary absorption
versus stellar activity caused by a star-planet interaction. Further
out-of-transit monitoring at higher signal-to-noise would be useful to more
strictly constrain the frequency of the near-transit changes in the H$\alpha$
line core.

25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
4
The categories of this paper are: cond-mat
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
24
The categories of this paper are: dg-ga
7
The categories of this paper are: hep-th
16
The categories of this paper are: stat
29
The categories of this paper are: funct-an
37
The categories of this paper are: supr-con
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
18
The categories of this paper are: econ
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph