NGC 1535

NGC 1535是一个位于波江座的行星状星云，由威廉·赫歇尔发现于1785年2月1日。NGC 1535的直径约稍大于1光年，距离地球约5500到7500光年。它的颜色和结构与爱斯基摩星云极为类似，但依照观测资料，这两个星云中心恒星的性质极为不同。

NGC 1535 is a planetary nebula in the equatorial constellation of Eridanus. It is known as Cleopatra's Eye, and is located around 5500-7500 light years away from Earth. This nebula was discovered by German-British astronomer William Herschel on February 1, 1785. The object is included in the Astronomical League's Herschel 400 Observing Program.

Characteristics

It is very similar to the Eskimo Nebula in both color and structure. It has a round exhibiting moderate ellipticity. The dust distribution inside NGC 1535 is uniform and nearly round in shape. It displays a dust halo with a noticeable inner ring of increased intensity. Outside this ring is a faint oval disk, note quite symmetrical with the main nebula. This region shows faint traces of ring formation in the southeastern region. The nebula seems to have formed in a somewhat metal-poor region having undergone little or no enhancement of elements mixing with nuclear-processed material.

NGC 1536 is a bright, high-excitatory nebula. Spectra of NGC 1535 from ROSAT reveal of “double hump” shape with approximately one-third of the photons are within the high energy range with more than 0.5 keV. These high energies could not simply have been produced by a stellar photosphere, even with the central star having a temperature of 250,000 Kelvin.

Observations by Leahy et al. using ROSAT reported X-ray emissions from NGC 3587 and NGC 1535. However comparisons between optical and X-ray images shows that these X-ray emissions coincide with a star that was outside the optical boundary of the nebula. This would make previous reports of X-ray emission from NGC 1535 likely false. Observations were taken using ROSAT High Resolution Imager which clearly confirms that the X-ray emissions contain three peaks that are point sources (RX J111447.9+550106, RX J111450.9+550208, and RX J111504.9+550141). Only the first of these sources are projected to…

Central star

At the center of NGC 1535, there is a O-type star with a spectral type of O(H)5. It is difficult to visually observe with a magnitude of 10. This star has a mass of 0.59☉ and a temperature of 66,000 Kelvin. The star produces stellar winds with a terminal velocity of about 200 km/sec. These stellar winds are suspected to be the dominant force, shaping the morphology of the nebula to a round shape.