Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hubble Space Telescope times-series photometry of the planetary transit
  of HD189733: no moon, no rings, starspots   We monitored three transits of the giant gas planet around the nearby K dwarf
HD 189733 with the ACS camera on the Hubble Space Telescope. The resulting
very-high accuracy lightcurve (signal-to-noise ratio near 15000 on individual
measurements, 35000 on 10-minute averages) allows a direct geometric
measurement of the orbital inclination, radius ratio and scale of the system: i
= 85.68 +- 0.04, Rpl/R*=0.1572 +- 0.0004, a/R*=8.92 +- 0.09. We derive improved
values for the stellar and planetary radius, R*=0.755+- 0.011 Rsol, Rpl=1.154
+- 0.017 RJ, and the transit ephemerides, Ttr=2453931.12048 +- 0.00002 + n
2.218581 +- 0.000002$. The HST data also reveal clear evidence of the planet
occulting spots on the surface of the star. At least one large spot complex
(>80000 km) is required to explain the observed flux residuals and their colour
evolution. This feature is compatible in amplitude and phase with the
variability observed simultaneously from the ground. No evidence for satellites
or rings around HD 189733b is seen in the HST lightcurve. This allows us to
exlude with a high probability the presence of Earth-sized moons and
Saturn-type debris rings around this planet. The timing of the three transits
sampled is stable to the level of a few seconds, excluding a massive second
planet in outer 2:1 resonance.

0
The categories of this paper are: hep-ph
24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
4
The categories of this paper are: cond-mat
14
The categories of this paper are: math-ph
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics
23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
29
The categories of this paper are: funct-an
18
The categories of this paper are: econ