IC 4593
Nebula in the constellation Hercules
From Wikipedia, the free encyclopedia
IC 4593 (also known as the White-Eyed Pea Nebula) is a planetary nebula in the constellation Hercules.[2] It was first discovered in 1907 by astronomer Williamina Fleming.[5] The nebula is approximately 0.96 light-years across.[6] At the center of the nebula is a hot white dwarf that's known as HD 145649, which is an O-type star with a spectral type of O7f.[7] The temperature of the white dwarf is approximately 30,000 to 40,000 K.[8][9]
| Nebula | |
|---|---|
IC 4593 imaged by astronomer Judy Schmidt | |
| Observation data: J2000.0 epoch | |
| Class | O7f[1] |
| Right ascension | 16h 11m 44.5s[2] |
| Declination | +12° 04′ 17″[3] |
| Distance | 7,900[4] ly |
| Apparent magnitude (V) | 10.7[2] |
| Apparent dimensions (V) | 0.22 × 0.22[2] |
| Constellation | Hercules[2] |
A study published in 2020 found that there are bubbles of extremely hot gas in its inner cavities, with the gas heating to over a million degrees. They were formed because of stellar winds colliding with previously expelled gas.[10]
Characteristics
IC 4593 is homogeneous and amorphous, with little to no clustering when compared to other planetary nebulae.[9][11]
The star is surrounded by an asymmetrical inner core about 10 arcseconds across. The core has a faint but fast gas flow, reaching speeds of over 100 kilometers per second. The star has a dense ring-like structure around it. There are bright, low-ionized knots that extend out of the core and into the inner halo. The knots can be best seen in nitrogen emission lines. The inner halo is partially enclosed by a shell, creating a visible arc shape or bulge near the northwest part of the halo.[12][13]
The outer halo is irregluar and unaligned with the inner halo.[12] The halo is faint and fragmented.[14]
