Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A High Resolution Radio Survey of Class I Protostars   We report the results of a survey of low mass Class I protostars in the cm
continuum. In the initial survey, seven sources in the Taurus star formation
were observed with the VLA at 0``.25 resolution. All seven sources drive CO
outflows and display Herbig-Haro flows in the optical or near infrared
wavebands. 4/7 sources were detected, two of which are new discoveries in
systems of very low luminosity, one being the lowest luminosity system detected
to date in the cm continuum. Notably, three sources were not detected to a
3-sigma limit of 0.10 mJy/beam, which indicates that significant cm continuum
emission is not a universal feature of Class I systems with outflow activity.
Subsequent observations of HH30, a more evolved Class II system, found no
emission to a 3-sigma limit of 0.03 mJy/beam. After comparison with near
infrared data, we suggest that the discriminating feature of the detected
systems is a relatively high ionisation fraction in the stellar wind. Temporal
variability of the outflow may also play a role. The one relatively bright
source, IRAS 04016+2610 (L1489 IRS), is clearly resolved on a 0``.4 scale at 2
cm and 3.5 cm. Follow-up imaging with MERLIN did not detect this source with a
0``.04 beam, indicating that the radio emission is generated in a region with a
radius of about 25 au, which is broadly similar to the radius of the bipolar
cavities inferred from models of near infrared data. Interpretation of this
system is complicated by the existence of a quadrupolar outflow, which we
originally detected through polarimetric imaging. We present a near infrared H2
image in which a bow shock in the secondary outflow is clearly seen. This
complicated structure may have been caused by a gravitational interaction
between two protostars.

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The categories of this paper are: acc-phys
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The categories of this paper are: atom-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: hep-ex
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The categories of this paper are: eess
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The categories of this paper are: quant-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: cond-mat
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The categories of this paper are: q-alg
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The categories of this paper are: gr-qc
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The categories of this paper are: q-bio
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The categories of this paper are: alg-geom
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The categories of this paper are: q-fin
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The categories of this paper are: dg-ga