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Accepted manuscript

ASKAP EMU Radio Detection of the Reflection Nebula VdB-80 in the Monoceros Crossbones Filamentary Structure

Published online by Cambridge University Press:  12 February 2025

A. C. Bradley Open the ORCID record for A. C. Bradley [Opens in a new window] ,
Z. J. Smeaton Open the ORCID record for Z. J. Smeaton [Opens in a new window] ,
N. F. H. Tothill ,
M. D. Filipović ,
W. Becker ,
A. M. Hopkins Open the ORCID record for A. M. Hopkins [Opens in a new window] ,
B. S. Koribalski Open the ORCID record for B. S. Koribalski [Opens in a new window] ,
S. Lazarević Open the ORCID record for S. Lazarević [Opens in a new window] ,
D. Leahy Open the ORCID record for D. Leahy [Opens in a new window]  and
G. Rowell
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A. C. Bradley*
Affiliation:
Western Sydney University, Locked Bag 1797, Penrith South DC, NSW 2751, Australia
Z. J. Smeaton
Affiliation:
Western Sydney University, Locked Bag 1797, Penrith South DC, NSW 2751, Australia
N. F. H. Tothill
Affiliation:
Western Sydney University, Locked Bag 1797, Penrith South DC, NSW 2751, Australia
M. D. Filipović
Affiliation:
Western Sydney University, Locked Bag 1797, Penrith South DC, NSW 2751, Australia
W. Becker
Affiliation:
Max-Planck Institut für extraterrestrische Physik, Gießenbachstraße 1, 85748 Garching, Germany Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
A. M. Hopkins
Affiliation:
School of Mathematical and Physical Sciences, 12 Wally’s Walk, Macquarie University, NSW 2109, Australia
B. S. Koribalski
Affiliation:
Western Sydney University, Locked Bag 1797, Penrith South DC, NSW 2751, Australia Australia Telescope National Facility, CSIRO, Space and Astronomy, PO Box 76, Epping, NSW 1710, Australia
S. Lazarević
Affiliation:
Western Sydney University, Locked Bag 1797, Penrith South DC, NSW 2751, Australia Australia Telescope National Facility, CSIRO, Space and Astronomy, PO Box 76, Epping, NSW 1710, Australia Astronomical Observatory, Volgina 7, 11060 Belgrade, Serbia
D. Leahy
Affiliation:
Dept. of Physics and Astronomy, University of Calgary, Calgary, AB, T2N 1N4, Canada
G. Rowell
Affiliation:
School of Physics, Chemistry and Earth Sciences, The University of Adelaide, Adelaide 5005, Australia
V. Velović
Affiliation:
Western Sydney University, Locked Bag 1797, Penrith South DC, NSW 2751, Australia
D. Urošević
Affiliation:
Department of Astronomy, Faculty of Mathematics, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia
*
Author for correspondence: A. C. Bradley, Email: 20295208@student.westernsydney.edu.au.
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Abstract

We present a new radio detection from the Australian Square Kilometre Array Pathfinder (ASKAP) Evolutionary Map of the Universe (EMU) survey associated with the Reflection Nebula (RN) VdB-80. The radio detection is determined to be a previously unidentified Hii region, now named Lagotis. The RN is located towards Monoceros, centred in the molecular cloud feature known as the ‘Crossbones’. The 944 M̃Hz EMU image shows a roughly semicircular Hii region with an integrated flux density of 30.2±0.3 mJy. The Hii region is also seen at 1.4 GHz by NRAO VLA Sky Survey (NVSS), yielding an estimated spectral index of 0.65±0.51, consistent with thermal radio emission. Gaia Data Release 3 (DR3) and Two Micron All Sky Survey (2MASS) data give a distance to the stars associated with the Hii region of ∼960 pc. This implies a size of 0.76×0.68(±0.09) pc for the Hii region. We derive an Hii region electron density of the bright radio feature to be 26 cm−3, requiring a Lyman-alpha photon flux of 1045.6 s−1, which is consistent with the expected Lyman flux of HD46060, the B2 ii type star which is the likely ionising star of the region. The derived distance to this region implies that the Crossbones feature is a superposition of two filamentary clouds, with Lagotis embedded in the far cloud.

Keywords

ISM: nebulaeISM: Hii regionISM: cloudsISM: moleculesproper motionsstars: distances
Type
Research Article
Information
Publications of the Astronomical Society of Australia , Accepted manuscript , pp. 1 - 9
Copyright
© The Author(s), 2025. Published by Cambridge University Press on behalf of Astronomical Society of Australia

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