Sextans is a minor
equatorial Equatorial may refer to something related to:
*Earth's equator
**the tropics, the Earth's equatorial region
**tropical climate
*the Celestial equator
** equatorial orbit
**equatorial coordinate system
** equatorial mount, of telescopes
* equatorial ...
constellation which was introduced in 1687 by
Johannes Hevelius
Johannes Hevelius
Some sources refer to Hevelius as Polish:
*
*
*
*
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*
Some sources refer to Hevelius as German:
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*of the Royal Society
* (in German also known as ''Hevel''; pl, Jan Heweliusz; – 28 January 1687) was a councillor ...
. Its name is
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
for the
astronomical sextant, an instrument that Hevelius made frequent use of in his observations.
Notable features
Sextans as a
constellation covers a rather dim, sparse region of the sky. It has only one star above the
fifth magnitude, namely
α Sextantis at 4.49
m. The constellation contains a few
double stars, including
γ,
35, and
40 Sextantis. There are a few notable
variable star
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as e ...
s, including
β,
25,
23 Sextantis, and
LHS 292.
NGC 3115
NGC 3115 (also called the Spindle Galaxy or Caldwell 53) is a field lenticular (S0) galaxy in the constellation Sextans. The galaxy was discovered by William Herschel on February 22, 1787. At about 32 million light-years away from Earth, it i ...
, an edge-on
lenticular galaxy
A lenticular galaxy (denoted S0) is a type of galaxy intermediate between an elliptical (denoted E) and a spiral galaxy in galaxy morphological classification schemes. It contains a large-scale disc but does not have large-scale spiral arms. ...
, is the only noteworthy
deep-sky object
A deep-sky object (DSO) is any astronomical object that is not an individual star or Solar System object (such as Sun, Moon, planet, comet, etc.). The classification is used for the most part by amateur astronomers to denote visually observed f ...
. It also lies near the ecliptic, which causes the
Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
, and some of the planets to occasionally pass through it for brief periods of time.
The constellation is the location of the field studied by the
COSMOS project, undertaken by the
Hubble Space Telescope
The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most vers ...
.
Sextans B is a fairly bright
dwarf irregular galaxy at magnitude 6.6, 4.3 million
light-years from
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
. It is part of the
Local Group
The Local Group is the galaxy group that includes the Milky Way.
It has a total diameter of roughly , and a total mass of the order of .
It consists of two collections of galaxies in a "dumbbell" shape: the Milky Way and its satellites form ...
of galaxies.
CL J1001+0220 is as of 2016 the most distant-known
galaxy cluster
A galaxy cluster, or a cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity, with typical masses ranging from 1014 to 1015 solar masses. They are the second-lar ...
at
redshift z=2.506, 11.1 billion light-years from Earth.
In June 2015, astronomers reported evidence for
population III stars
During 1944, Walter Baade categorized groups of stars within the Milky Way into stellar populations.
In the abstract of the article by Baade, he recognizes that Jan Oort originally conceived this type of classification in 1926:
Baade noticed th ...
in the
Cosmos Redshift 7 galaxy (at ''z'' = 6.60) found in Sextans. Such stars are likely to have existed in the very early
universe
The universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. The Big Bang theory is the prevailing cosmological description of the development of the universe. ...
(i.e., at high redshift), and may have started the production of
chemical element
A chemical element is a species of atoms that have a given number of protons in their nuclei, including the pure substance consisting only of that species. Unlike chemical compounds, chemical elements cannot be broken down into simpler sub ...
s heavier than
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...
that are needed for the later formation of
planet
A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...
s and
life
Life is a quality that distinguishes matter that has biological processes, such as Cell signaling, signaling and self-sustaining processes, from that which does not, and is defined by the capacity for Cell growth, growth, reaction to Stimu ...
as we know it.
Gallery
See also
*
Sextans (Chinese astronomy)
References
*
* Ian Ridpath and Wil Tirion (2007). ''Stars and Planets Guide'', Collins, London. . Princeton University Press, Princeton. .
External links
The Deep Photographic Guide to the Constellations: Sextans
{{DEFAULTSORT:Constellation, Sextans
Equatorial constellations
Constellations listed by Johannes Hevelius