A new catalogue of HI supershell candidates in the outer part of the Galaxy

LAURA SUAD; CESAR F. CAIAFA; MARCELO ARNAL; SILVINA CICHOWOLSKI

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2014 vol. 564 p. 1 - 14

0004-6361

Aims. The main goal of this work is to a have a new neutral hydrogen (HI) supershell candidates catalogue to analyze their spatial distribution in the Galaxy, and to carry out a statistical study of their main properties. Methods. This catalogue was carried out making use of the Leiden-Argentine-Bonn (LAB) survey. The identification of the supershell candidates was made using a combination of two techniques: a visual inspection one plus an automatic searching algorithm. Our automatic algorithm is able to detect both close and open structures. Results. A total of 566 supershell candidates were identified. Most of them (347) are located in the second galactic quadrant, while 219 were unveiled in the third one. Most of them are elliptical in shape and have their major axes parallel to the galactic plane. The weighted mean value of the effective radius of the structures is approx. 160 pc. Owing to the ability of our automatic algorithm to detect open structures, we have also identified some galactic chimney candidates. We find an asymmetry between the second and third galactic quadrants in the sense that in the second one we detect structures as far as 32 kpc while for the 3rd one the farthest structure is detected at 17 kpc. The supershell surface density in the solar neighborhood is approx. 8 kpc2, and decreases as we move further away form the galactic center. We have also compared our catalogue with those published by other authors.