IC 4997 is a planetary nebula located in the constellation of Delphinus. [4] It was discovered in 1896 by Edward Charles Pickering and Williamina Fleming, [5] and independently by Gustav Gruss the same year. [6] This nebula is about 14,000 light-years from Earth. [2]

IC 4997, in extreme southeastern Sagitta (between the classical figures of Sagitta and Delphinus), is one of several "stellar" planetary nebulae that to the eye are physically so small or so far away (or both) that they just look like stars. In Curtis's photo the nebula appears as no more than a …

2021年12月27日 · IC\,4997 is a planetary nebula well known by its variability. We present high-resolution spectra of IC\,4997 obtained in 1993, 2019, and 2020 that reveal changes in the H and [N\, {\sc ii}] emission line profiles, which had never been reported for this object.

IC 4997 is a Planetary Nebula in the Delphinus constellation. IC 4997 is situated close to the celestial equator and, as such, it is at least partly visible from both hemispheres in certain times of the year.

2020年2月23日 · We present the results of a new epoch of a long-term photometric monitoring of the variable planetary nebula IC~4997. The integral UBV light curves display a continuing brightening of 0. m15 in V, a slight rise (<0. m1) in B, and constancy in U.

2022年6月28日 · Using the Five-hundred-meter Aperture Spherical radio Telescope in Guizhou, China, we detect the 21 cm neutral atomic hydrogen absorption in the young planetary nebula IC 4997. The absorption arises from a shell that is also associated with Na i D lines. The H i shell has a mass of 1.46 × 10 −2 M⊙ and a dynamic age of 990 yr.

The compact, dusty, presumably young planetary nebula (PN) IC 4997 has been studied extensively since the variability of the lambda 4363/lambda 4340 ratio was established in 1956. Since 1938, other nebular lines have shown changes.

From Virginia Beach , IC4997 is visible in the dawn sky, rising at 02:11 (EDT) and reaching an altitude of 43° above the eastern horizon before fading from view as dawn breaks at around 05:54. "PK Catalogue of Galactic Planetary Nebulae", L. Kohoutek, 2000. All times shown in Virginia Beach local time.

1996年4月20日 · The radio continuum map shows that IC 4997 is a double-shell planetary nebula consisting of a faint, knotty outer shell of size ≃2 7 × 1 4, elongated at position angle ≃54°, and a bright, circular inner shell of ≃0 28 in diameter. The outer shell presents an hourglass-like morphology and exhibits a striking mirror symmetry with respect ...

IC 4997 is a planetary nebula well known by its variability. We present high-resolution spectra of IC 4997 obtained in 1993, 2019, and 2020 that reveal changes in the Hα and [N II] emission line profiles, which had never been reported for this object.