Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hydrogen dominated atmospheres on terrestrial mass planets: evidence,
  origin and evolution   The discovery of thousands of highly irradiated, low-mass, exoplanets has led
to the idea that atmospheric escape is an important process that can drive
their evolution. Of particular interest is the inference from recent exoplanet
detections that there is a large population of low mass planets possessing
significant, hydrogen dominated atmospheres, even at masses as low as $\sim
2$~M$_\oplus$. The size of these hydrogen dominated atmospheres indicates the
the envelopes must have been accreted from the natal protoplanetary disc. This
inference is in contradiction with the Solar System terrestrial planets, that
did not reach their final masses before disc dispersal, and only accreted thin
hydrogen dominated atmospheres. In this review, we discuss the evidence for
hydrogen dominated atmospheres on terrestrial mass ($\lesssim$ 2~M$_\oplus$)
planets. We then discuss the possible origins and evolution of these
atmospheres with a focus on the role played by hydrodynamic atmospheric escape
driven by the stellar high-energy emission (X-ray and EUV; XUV).

13
The categories of this paper are: quant-ph
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
30
The categories of this paper are: q-alg
28
The categories of this paper are: alg-geom
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th