Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Strings in the Eta Carinae Nebula: Hypersonic Radiative Cosmic Bullets   We present the results of a numerical study focusing on the propagation of a
hypersonic bullet subject to radiative cooling. Our goal is to explore the
feasibility of such a model for the formation of ``strings'' observed in the
Eta Carinae Homunculus nebula. Our simulations were performed in cylindrical
symmetry with the adaptive mesh refinement code AstroBEAR. The radiative
cooling of the system was followed using the cooling curve by Dalgarno & McCray
(1972). In this letter we discuss the evolution and overall morphology of the
system as well as key kinematic properties. We find that radiative bullets can
produce structures with properties similar to those of the Eta Carinae strings,
i.e. high length-to-width ratios and Hubble-type flows in the form of a linear
velocity increase from the base of the wake to the bullet head. These features,
along with the appearance of periodic ``ring-like'' structures, may also make
this model applicable to other astrophysical systems such as planetary nebulae,
e.g. CRL 618 and NGC 6543, young stellar objects, etc.

16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
32
The categories of this paper are: atom-ph
19
The categories of this paper are: eess
18
The categories of this paper are: econ
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci