According to the active galactic nucleus unified model proposed in the 1980s, a supermassive black hole exists at the center of the galaxies, and the black hole is surrounded by a thick and ...

Today, it is believed that there is a supermassive black hole at the center of most galaxies. Many galaxies are observed to host “active galactic nuclei”, which form the bright central region of the ...

The ultraviolet spectra of quasi-stellar objects (QSOs) are characterized by prominent emission features originating from transitions such as C IV, Si IV, N V, and additional lower ionization ...

Water vapour continuum absorption refers to the smooth, broadband absorption observed in the atmospheric windows, which fills the spectral gaps between distinct molecular absorption lines. This ...

Abstract: Nowadays, with more sky survey projects, astronomical data are generated in large quantities, and the traditional astronomical data processing methods can no longer meet the current data ...

The Zeeman effect and optical pumping are two mechanisms capable of inducing polarization signals in the spectral lines that originate in the outer layers of stellar atmospheres. The Zeeman effect 12 ...

Abstract: We explore a disc origin for the highly blueshifted, variable absorption lines seen in the X-ray spectrum of the narrow-line Seyfert 1 galaxy IRAS 13224−3809. The blueshift corresponds to a ...

To see the various colors that make up starlight, astronomers can use a prism to separate the colors. Common elements like helium and calcium in the atmospheres of stars block certain colors of light, ...

Here are some interesting papers that discuss absorption lines produced by accretion disc atmospheres. Blueshifted absorption lines from X-ray reflection in IRAS 13224-3809 Fabian et al. (2020) The ...

Studying the line spectra produced by hot gases and absorbed by cooler gases allows us to identify the elements in stars. When a gas is very hot, it doesn’t emit all wavelengths of light. Hot gases ...