The INT Photometric H-Alpha Survey
Encyclopedia
The INT Photometric H-Alpha
Survey (IPHAS) is an astronomical survey of the northern plane of our Galaxy
, the Milky Way
, as visible from the Isaac Newton Telescope
(INT) in the Canary Islands
, Spain
. The survey uses two broad-band filters
and a narrow H-alpha
filter to obtain deep images of nebulae in our Galaxy and for identifying rare types of stars. Observations for the survey began in 2003 and are almost complete. The survey will soon be complemented by a sister survey of the southern Galactic plane. Once these two surveys are completed the data is expected to provide a significant leap in our knowledge of the extreme phases of stellar evolution.
The goals of the survey include:
Because of the selection for young stars and nebulae, the survey will also increase the number of known OB associations
, and other clusters.
in this image.
H-alpha
H-alpha is a specific red visible spectral line created by hydrogen with a wavelength of 656.28 nm, which occurs when a hydrogen electron falls from its third to second lowest energy level...
Survey (IPHAS) is an astronomical survey of the northern plane of our Galaxy
Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...
, the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
, as visible from the Isaac Newton Telescope
Isaac Newton Telescope
The Isaac Newton Telescope or INT is a 2.54 m optical telescope run by the ING at Roque de los Muchachos Observatory on La Palma in the Canary Islands since 1984....
(INT) in the Canary Islands
Canary Islands
The Canary Islands , also known as the Canaries , is a Spanish archipelago located just off the northwest coast of mainland Africa, 100 km west of the border between Morocco and the Western Sahara. The Canaries are a Spanish autonomous community and an outermost region of the European Union...
, Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
. The survey uses two broad-band filters
Photographic filter
In photography and videography, a filter is a camera accessory consisting of an optical filter that can be inserted in the optical path. The filter can be a square or oblong shape mounted in a holder accessory, or, more commonly, a glass or plastic disk with a metal or plastic ring frame, which...
and a narrow H-alpha
H-alpha
H-alpha is a specific red visible spectral line created by hydrogen with a wavelength of 656.28 nm, which occurs when a hydrogen electron falls from its third to second lowest energy level...
filter to obtain deep images of nebulae in our Galaxy and for identifying rare types of stars. Observations for the survey began in 2003 and are almost complete. The survey will soon be complemented by a sister survey of the southern Galactic plane. Once these two surveys are completed the data is expected to provide a significant leap in our knowledge of the extreme phases of stellar evolution.
The goals of the survey include:
- Identification of rare objects that are often characterized by strong emission in H-AlphaH-alphaH-alpha is a specific red visible spectral line created by hydrogen with a wavelength of 656.28 nm, which occurs when a hydrogen electron falls from its third to second lowest energy level...
compared to that in broad-band filters. This includes massive OB stars, supergiants, interacting binary stars and supernovaSupernovaA supernova is a stellar explosion that is more energetic than a nova. It is pronounced with the plural supernovae or supernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months...
progenitors. - Mapping Galactic extinctionExtinction (astronomy)Extinction is a term used in astronomy to describe the absorption and scattering of electromagnetic radiation by matter between an emitting astronomical object and the observer. Interstellar extinction—also called Galactic extinction, when it occurs in the Milky Way—was first...
and nebulosity. - Identifying compact and extended planetary nebulaePlanetary nebulaA planetary nebula is an emission nebula consisting of an expanding glowing shell of ionized gas ejected during the asymptotic giant branch phase of certain types of stars late in their life...
and symbiotic stars. - Cataloging of vast numbers of stars in our Galaxy.
Because of the selection for young stars and nebulae, the survey will also increase the number of known OB associations
Star cluster
Star clusters or star clouds are groups of stars. Two types of star clusters can be distinguished: globular clusters are tight groups of hundreds of thousands of very old stars which are gravitationally bound, while open clusters, more loosely clustered groups of stars, generally contain less than...
, and other clusters.
Discoveries
The survey has already discovered a large number of previously unknown planetary nebulae, such as the Necklace NebulaNecklace Nebula
The Necklace Nebula is a planetary nebula located about 15,000 light-years away in the northern constellation Sagitta. It was discovered in 2005 from the Isaac Newton Telescope Photometric H-alpha Survey , a ground-based H-alpha planetary nebula study of the North Galactic Plane...
in this image.