Starship Asterisk*

neufer wrote: ↑Thu Sep 16, 2021 2:27 pm <<In 1922, Edwin Hubble proposed that Deneb may be responsible for lighting up the North America Nebula, but it soon became apparent that it is not hot enough: Deneb has a surface temperature of 8,500 K, while the nebula’s spectrum shows it is being heated by a star hotter than 30,000 K. In addition, Deneb is well away from the middle of the complete North America/Pelican nebula complex (Sh2-117), and by 1958 George Herbig realised that the ionizing star had to lie behind the central dark cloud L935. In 2004, European astronomers Fernando Comerón and Anna Pasquali searched for the ionizing star behind L935 at infrared wavelengths, using data from the 2MASS survey, and then made detailed observations of likely suspects with the 2.2 m telescope at the Calar Alto Observatory in Spain. One star, catalogued J205551.3+435225, fulfilled all the criteria. Lying right in the centre of Sh2-117, with a temperature of over 40,000 K, it is almost certainly the ionising star for the North America and Pelican Nebulae.

neufer wrote: ↑Thu Sep 16, 2021 2:27 pm

Ann wrote: ↑Thu Sep 16, 2021 5:15 am
It really looks as if the North America Nebula and the Pelican Nebula are in fact one and the same large region of emission nebulosity. So the one million dollar question is, what and where is the star ionizing it all?

https://en.wikipedia.org/wiki/North_America_Nebula wrote:

North America and Pelican Nebulae viewed in optical (top left) and successively longer infrared wavelengths, which penetrate the dust cloud between them.

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<<In 1922, Edwin Hubble proposed that Deneb may be responsible for lighting up the North America Nebula, but it soon became apparent that it is not hot enough: Deneb has a surface temperature of 8,500 K, while the nebula’s spectrum shows it is being heated by a star hotter than 30,000 K. In addition, Deneb is well away from the middle of the complete North America/Pelican nebula complex (Sh2-117), and by 1958 George Herbig realised that the ionizing star had to lie behind the central dark cloud L935. In 2004, European astronomers Fernando Comerón and Anna Pasquali searched for the ionizing star behind L935 at infrared wavelengths, using data from the 2MASS survey, and then made detailed observations of likely suspects with the 2.2 m telescope at the Calar Alto Observatory in Spain. One star, catalogued J205551.3+435225, fulfilled all the criteria. Lying right in the centre of Sh2-117, with a temperature of over 40,000 K, it is almost certainly the ionising star for the North America and Pelican Nebulae.

Later observations have revealed J205551.3+435225 is a spectral type O3.5 star, with another hot star (type O8) in orbit. J205551.3+435225 lies just off the “Florida coast” of the North America Nebula, so it has been more conveniently nicknamed the Bajamar Star ("Islas de Bajamar," meaning "low-tide islands" in Spanish, was the original name of the Bahamas because many of them are only easily seen from a ship during low tide).

Although the light from the Bajamar Star is dimmed by 9.6 magnitudes (almost 10,000 times) by the dark cloud L935, it is faintly visible at optical wavelengths, at magnitude 13.2. If we saw this star undimmed, it would shine at magnitude 3.6, almost as bright as Albireo, the star marking the swan's head.

Ann wrote: ↑Thu Sep 16, 2021 5:15 am
It really looks as if the North America Nebula and the Pelican Nebula are in fact one and the same large region of emission nebulosity. So the one million dollar question is, what and where is the star ionizing it all?

https://en.wikipedia.org/wiki/North_America_Nebula wrote:

North America and Pelican Nebulae viewed in optical (top left) and successively longer infrared wavelengths, which penetrate the dust cloud between them.

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Click to play embedded YouTube video.

<<In 1922, Edwin Hubble proposed that Deneb may be responsible for lighting up the North America Nebula, but it soon became apparent that it is not hot enough: Deneb has a surface temperature of 8,500 K, while the nebula’s spectrum shows it is being heated by a star hotter than 30,000 K. In addition, Deneb is well away from the middle of the complete North America/Pelican nebula complex (Sh2-117), and by 1958 George Herbig realised that the ionizing star had to lie behind the central dark cloud L935. In 2004, European astronomers Fernando Comerón and Anna Pasquali searched for the ionizing star behind L935 at infrared wavelengths, using data from the 2MASS survey, and then made detailed observations of likely suspects with the 2.2 m telescope at the Calar Alto Observatory in Spain. One star, catalogued J205551.3+435225, fulfilled all the criteria. Lying right in the centre of Sh2-117, with a temperature of over 40,000 K, it is almost certainly the ionising star for the North America and Pelican Nebulae.

Later observations have revealed J205551.3+435225 is a spectral type O3.5 star, with another hot star (type O8) in orbit. J205551.3+435225 lies just off the “Florida coast” of the North America Nebula, so it has been more conveniently nicknamed the Bajamar Star ("Islas de Bajamar," meaning "low-tide islands" in Spanish, was the original name of the Bahamas because many of them are only easily seen from a ship during low tide).

Although the light from the Bajamar Star is dimmed by 9.6 magnitudes (almost 10,000 times) by the dark cloud L935, it is faintly visible at optical wavelengths, at magnitude 13.2. If we saw this star undimmed, it would shine at magnitude 3.6, almost as bright as Albireo, the star marking the swan's head.