There are countless stars in the sky, how are they named and identified?

There are many stars visible in the night sky, but over the centuries astronomers have devised a unique way to recognize them.

Surely among us there have been those who spent a night curiously looking up at the sky and marveling at the amazing sight of stars, planets, constellations and even galaxies. . Those with years of experience looking at the night sky can even spot some brighter stars.

There are countless stars in that mysterious night, even without the use of telescopes or other optical aids, we can still see hundreds of stars in the clear sky. away from the lights of the city. So have you ever asked the question: how are all those stars named and confirmed?

Image of the constellation Gemini from Bayer .'s star atlas

To answer this question, we first need to take a look at some brief historical milestones in how humans have named stars over the centuries. The most prominent and brightest stars in the night sky often had names given in the past and are still in use today. However, professional astronomy today involves giving the designations to the stars as alphanumeric, used in all official catalogs.

For example, the brightest star in the constellation Lyra is named Vega, but it has the symbols Alpha Lyrae (Bayer symbol), 3 Lyrae (Flamsteed symbol), HR 7001 (from the Catalog of Bright Stars of the United States). Yale) and other names in several other categories.

We will look at the names that have been given to the stars, which are either proper and of ancient, recent or given names by various organizations of the International Astronomical Union (IAU). The oldest proper names are mostly of ancient Greek origin. Some good examples such as Sirius - the celestial star, the star Procyon (also the name of an animal genus), the star Arcturus - follows the constellation Ursa Major (the great bear).

Diagram of the famous Spring Triangle. The star Arcturus follows Ursa Major, while it moves across the sky.

However, most of the proper names of stars are of Arabic origin, as they were labeled by Arab astronomers during the Middle Ages. These names have many legends and origins behind them, based on the positions of the stars in their constellations. For example, the naming of Deneb, which means "tail", Aldebaran, meaning "watcher", and Fomalhaut, meaning "mouth of a whale".

This chart contains the proper names of prominent stars in the constellation Leo. The Greek letters in parentheses are the Bayer symbols of the respective stars.

Currently, naming a star a personal name is not of much concern. Not only does it involve a lot of paperwork, but there have been cases where two or more stars received the same proper names, such as 'Deneb' in Cygnus, 'Denebola' in Leo, and 'Deneb' Kaitos' in the constellation Cetus. In some cases, when Arabic names are translated into other languages, such as Latin, the meaning of the stars' names is sometimes lost.

In 1600, Johannes Bayer released his catalog of naming stars. In it, he used lowercase Greek letters for the stars, in roughly descending order of luminosity, in the same constellation. The most convincing interpretation of this is therefore that the brightest star in a constellation would be denoted 'Alpha', the second brightest star would be 'Beta', etc. Lap is followed by the Latin tribal name of the constellation. For example, Sirius, the brightest star in the constellation Canis Major, is named "Alpha Canis Majoris" with the Latin genome, "Canis Majoris," which simply means "belongs to Canis Major".

The constellation Orion and other nearby constellations show the Bayer symbols of its constituent stars.

However, Bayer doesn't always follow its own luminance scheme. If we look at the constellation Ursa Major, he simply assigns Greek letters to the stars from west to east. where the first and second brightest stars are called "Beta Geminorum'" and "Alpha Geminorum", respectively.

Another fact is that there are only 24 Greek letters. Bayer attempted to solve this problem by using the lowercase Latin letters a through z (numbered with the 25th to 50th stars) and then using the uppercase Latin alphabet AZ (numbered with the 25th to 50th stars). assigned to stars 51 to 76). However, these programs are not commonly used.

Two hundred years after Bayer first introduced his system, John Flamsteed introduced his numerical classification system. In this diagram, the stars are numbered from West to East in each constellation. Therefore, the westernmost star in the constellation Taurus is named 1 Tauri, the second westernmost star will be named 2 Tauri, etc. Note that the Latin tribe of the constellation is added after the number. Flamesteed. Overall, more than 2,600 stars received the Flamsteed number.

Image of core stars in the Hyades cluster.

Both the names Bayer and Flamsteed include bright and prominent stars in a constellation. As fainter and less prominent stars were discovered over time, it was necessary to establish a new system to identify these stars. Thus, new categories based on the star's position in the sky were created, using a coordinate system similar to the Earth's latitudes, without considering the parent constellation.

One of the most common categories used in Astronomy is the Yale Bright Star Catalog. The stars in this category are designated 'HR' or 'BS', followed by a 4-digit number. Here, 'HR' refers to 'Harvard Revised', since the cataloging was first done by Harvard, before Yale began publishing it. This catalog includes approximately 9,110 stars, some examples of this classification include HR 2326 (Personal Name: Canopus) and HR 7001 (Personal Name: Vega).

Sky map with star positions from the Bright Star Catalog

Another catalog commonly used in astronomy is the Henry Draper Catalog (HD). The catalog also uses stellar positions in the night sky and lists more than 225,000 stars, whose names are prefixed with the prefix "HD" followed by a six-digit number. It also contains information about the spectral classes of the stars - an indication of the type of radiation emitted by the star. The HD catalog features stars that are both bright and dim.

A well-known catalog for identifying faint stars is Durchmusterung. This list includes stars 50 times fainter than the faintest stars visible to the naked eye, which are stars observed from surveys such as the Bonn Survey ('Bonner Durchmusterung'). ' in German) and Survey of Cordoba ('Cordoba Durchmusterung' in German). 

Other commonly used categories include the Smithsonian Astrophysical Observatory (SAO) catalog, the Position and Proper Motion (PPM) catalog, and the Hubble Space Telescope Guide Star category ( GSC). As an example of classification, the second brightest star in the constellation Orion has its own name 'Betelgeuse' and has the following symbols: Alpha Orionis (Bayer symbol), 58 Orionis (Flamsteed symbol), HR2061 (Nomenclature). Yale Bright Star entry), HD39801 (Henry Draper Catalog), BD+7 1055 (Bonner Durchmusterung Catalog) and SAO113271 (Smithsonian Astrophysics Laboratory Catalog).

Up to the present time, catalogs involving single stars have generally been of fixed magnitude. However, there are binary stars or clusters - two or more stars that appear very close together and may or may not be gravitationally aligned with each other - as well as stars that change over time. In this case, one of the commonly used methods to label them consists of assigning uppercase Latin letters in the order of their detection or in descending luminosity. Here, the main star will have an 'A' after its proper name or symbol, followed by the appropriate Latin letter for companion stars. For example, the brightest star in the sky, Sirius, has its main star designated Sirius A and its companion designated Sirius B.

A binary system with a primary star labeled Sirius A and a companion star Sirius B

For variable stars, the labeling was first proposed by Friedrich Wilhelm Argelander, who used the letters left over in Bayer notation. Bayer has gone the farthest with his classification as 'Q', the first variable star discovered in the constellation will be 'R', followed by 'S'. After the 'Z' is over, the double letter symbols, 'RR', 'RS' . up to 'ZZ' will be used. As more variable stars were found, astronomers began to label them from 'AA', 'AB'… 'BA'… to 'QZ'. An example of this diagram is R Cygni, as it was the first variable discovered in the constellation Cygnus.

Then astronomers simply use VV followed by a 3-digit number. For example, V335 Tauri in the constellation Taurus, is a variable star under this nomenclature.

Variable star labeled as RS Puppis, imaged by NASA's Hubble Space telescope

The naming and cataloging of stars is an important aspect of modern astronomy. Since more surveys mean a larger number of stars, naming them makes it easier to study their properties and characteristics. In some cases, the catalogs also contain more information about these stars.

Humans have made great strides in the study of stars and star systems, with stellar naming playing a very fundamental role in our understanding and appreciation of cosmic wonders.