Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observational indicators of the transition from fully convective stars
  to stars with radiative cores   We present a discussion of the similarities and key differences between the
transition onto (at the turn-on) and away from (at the turn-off) the main
sequence, the latter termed the Hertzsprung gap. Using a set of model
isochrones and adopting an initial mass function leads us to predict a dearth
of G-type stars for any star forming region. This is caused by the (relatively)
constant spectral type at which the transition from a fully convective star to
a star with a radiative core begins. We also present analysis of the details of
this transition in the ONC. In particular we show that a gap in the photometric
and spectral type distributions is centred on, and a change in the fractional
X-ray luminosity and rotation rate distribution occurs approximately at, the
position of a peak in radiative core size as a function of mass. Whilst
photometric signatures of this transition are lost at ages over ~20 Myrs, we
show that changes in fractional X-ray luminosity and magnetic field
configuration persist to older ages. Analysis of literature data show that the
mass at which the change in fractional X-ray luminosity is observed decreases
with age.

23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an
20
The categories of this paper are: acc-phys
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
32
The categories of this paper are: atom-ph
33
The categories of this paper are: plasm-ph
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc