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Largest Digital Survey of the Milky Way released

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12.12.2007

Astronomers at the University of Hertfordshire are part of a consortium which has just released the first major instalment of a comprehensive optical digital survey of the Milky Way.

Conducted by looking at light emitted by hydrogen ions, using the Isaac Newton Telescope on La Palma, the survey contains stunning red images of nebulae and stars. The data is described in a paper submitted to the Monthly Notices of the Royal Astronomical Society.

The University of Hertfordshire hosts the Principal Investigator and further members of the IPHAS consortium. IPHAS is a survey of the Northern Galactic Plane being carried out, in Ha, r and i filters, with the Wide Field Camera (WFC) on the 2.5-metre Isaac Newton Telescope (INT).

To date, the IPHAS survey includes some 200 million unique objects in the newly released catalogue. This immense resource will foster studies that can be at once both comprehensive and subtle, of the stellar demographics of the Milky Way and of its three-dimensional structure.

Professor Janet Drew of the University of Hertfordshire said: “Using the distinctive Hydrogen marker we are able to look at some of the least understood stars in the Galaxy – those at the early and very late stages of their life cycles. These represent less than one in a thousand stars, so the IPHAS data will lead to a greatly improve our picture of stellar evolution.”

This initial data release is of observations of the Northern Plane of the Milky Way (the star filled section) that cover 1600 sq deg, in two broadband colours, and a narrow band filter sensitive to the emission of Hydrogen in the red part of the spectrum (H-alpha emission). The image resolution is high enough to permit the detection of individual stars exhibiting H-alpha emission, in addition to the diffuse gas that makes up the often-beautiful glowing nebulae that lower spatial resolution surveys have made known to us before.

The IPHAS survey will eventually be extended to cover the entire galactic plane of our galaxy, with a coverage approaching 4000 square degrees (for comparison, the moon on the sky as seen from Earth covers ~0.1 square degrees).

Helene Murphy | Source: alphagalileo
Further information: arxiv.org/abs/0712.0384
www.herts.ac.uk

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