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Viola sororia ( / vaɪˈoʊlə səˈrɔːriə / vy-OH-lə sə-ROR-ee-ə ), [ 5] known commonly as the common blue violet, is a short-stemmed herbaceous perennial plant native to eastern North America. It is known by a number of common names, including common meadow violet, purple violet, woolly blue violet, hooded violet, and wood violet.
This class of stars was introduced with the Harvard sequence of stellar spectra and published in the Revised Harvard photometry catalogue. The definition of type B-type stars was the presence of non-ionized helium lines with the absence of singly ionized helium in the blue-violet portion of the spectrum. All of the spectral classes, including ...
Atmospheric optics. A colorful sky is often due to indirect sunlight being scattered off air molecules and particulates, like smog, soot, and cloud droplets, as shown in this photo of a sunset during the October 2007 California wildfires. Atmospheric optics is "the study of the optical characteristics of the atmosphere or products of ...
Color–color diagram. A color–color diagram is a means of comparing the colors of an astronomical object at different wavelengths. Astronomers typically observe at narrow bands around certain wavelengths, and objects observed will have different brightnesses in each band. The difference in brightness between two bands is referred to as an ...
Stellar classification. In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with spectral lines.
A G-type main-sequence star (spectral type: G-V), also often, and imprecisely, called a yellow dwarf, or G star, is a main-sequence star (luminosity class V) of spectral type G. Such a star has about 0.9 to 1.1 solar masses and an effective temperature between about 5,300 and 6,000 K (5,000 and 5,700 °C; 9,100 and 10,000 °F ).
The UBV photometric system (from Ultraviolet, Blue, Visual ), also called the Johnson system (or Johnson-Morgan system ), is a photometric system usually employed for classifying stars according to their colors. It was the first standardized photometric system. The apparent magnitudes of stars in the system are often used to determine the color ...
The initialism is sometimes referred to in reverse order, as VIBGYOR. More modernly, the rainbow is often divided into red, orange, yellow, green, cyan, blue and violet. [9] The apparent discreteness of main colours is an artefact of human perception and the exact number of main colours is a somewhat arbitrary choice.