Cosmos Redshift 7

Cosmos Redshift 7 (also known as COSMOS Redshift 7, Galaxy Cosmos Redshift 7, Galaxy CR7 or CR7) is a high-redshift Lyman-alpha emitter galaxy. At a redshift z = 6.6,[1] the galaxy is observed as it was about 800 million years after the Big Bang, during the epoch of reionisation.[1] With a light travel time of 12.9 billion years, it is one of the oldest, most distant galaxies known.

CR7 shows some of the expected signatures of Population III stars i.e. the first generation of stars produced during early galaxy formation.[1][2][3][4][5] These signatures were detected in a bright pocket of blue stars; the rest of the galaxy contains redder Population II stars.[3]

Cosmos Redshift 7
Eso1524aArtist’s impression of CR7 the brightest galaxy in the early Universe
Artist’s impression of CR7.
Observation data (Reionization epoch)
Right ascension 10h 00m 58.005s[1]
Declination+01° 48′ 15.251″[1]
Distance12.9 billion light-years[2]
TypeLyman-alpha emitter[1]
Notable features123 Galaxy Cosmos Redshift 7 is reported to be three times brighter than the brightest distant galaxy known up to the time of its discovery and to contain some of the earliest first stars that produced the chemical elements needed for the later formation of planets and life as it is known.[1]
Other designations
COSMOS Redshift 7; Galaxy Cosmos Redshift 7; Galaxy CR7; CR7


Galaxy Cosmos Redshift 7 contains old Population II (metal-poor) and Population III (extremely metal-poor) stars, according to astronomers,[1][2] and is three times brighter than the brightest distant galaxies (redshift, z > 6)[1][6] detected up to the time of its discovery.[3][5]


Astronomers led by David Sobral from Lisbon and Leiden used the Very Large Telescope (VLT) at the European Southern Observatory—with help from the W. M. Keck Observatory, Subaru Telescope and the NASA/ESA Hubble Space Telescope—made the discovery.[5] The research team included members of the University of California, Riverside,[5] University of Geneva, University of Leiden and University of Lisbon.[1] The name of the galaxy (Cosmos Redshift 7 Galaxy) was inspired by football player Cristiano Ronaldo, who is also popularly known as CR7.[3][7][8][9]

See also


  1. ^ a b c d e f g h i j k Sobral, David; Matthee, Jorryt; Darvish, Behnam; Schaerer, Daniel; Mobasher, Bahram; Röttgering, Huub J. A.; Santos, Sérgio; Hemmati, Shoubaneh (4 June 2015). "Evidence For POPIII-Like Stellar Populations In The Most Luminous LYMAN-α Emitters At The Epoch Of Re-Ionisation: Spectroscopic Confirmation". The Astrophysical Journal. 808 (2): 139. arXiv:1504.01734. Bibcode:2015ApJ...808..139S. doi:10.1088/0004-637x/808/2/139.
  2. ^ a b c Overbye, Dennis (17 June 2015). "Astronomers Report Finding Earliest Stars That Enriched Cosmos". New York Times. Retrieved 17 June 2015.
  3. ^ a b c d "Best Observational Evidence of First Generation Stars in the Universe" (Press release). European Southern Observatory. 17 June 2015.
  4. ^ Staff (17 June 2015). "Brightest galaxy and first-generation stars". Earth & Sky. Retrieved 17 June 2015.
  5. ^ a b c d Pittalwala, Iqbal (17 June 2015). "Astronomers Find Best Observational Evidence of First Generation Stars in the Universe". University of California, Riverside. Retrieved 17 June 2015.
  6. ^ Matthee, Jorryt; Sobral, David; et al. (21 July 2015). "Identification of the brightest Lyalpha emitters at z=6.6: implications for the evolution of the luminosity function in the re-ionisation era". MNRAS. 451 (1): 4919–4936. arXiv:1502.07355. Bibcode:2015MNRAS.451..400M. doi:10.1093/mnras/stv947.
  7. ^ Staff (17 June 2015). "Traces of Earliest Stars That Enriched Cosmos Are Spied". New York Times. Retrieved 17 June 2015.
  8. ^ Staff (18 June 2015). "Cristiano Ronaldo: CR7 name given to discovered galaxy". BBC. Retrieved 18 June 2015.
  9. ^ Staff (18 June 2015). "Cristiano Ronaldo: CR7 gets his own galaxy". CNN. Retrieved 18 June 2015.

External links

Coordinates: Sky map 10h 00m 58.005s, +01° 48′ 251″

Alpha Sextantis

Alpha Sextantis (α Sex, α Sextantis) is the brightest star in the equatorial constellation of Sextans. It is visible to the naked eye on a dark night with an apparent visual magnitude of 4.49. The distance to this star, as determined from parallax measurements, is around 280 light years. This is considered an informal "equator star", as it lies less than a quarter of a degree south of the celestial equator. In 1900, it was 7 minutes of arc north of the equator. As a result of a shift in the Earth's axial tilt, it crossed over to the Southern Hemisphere in December 1923.This is an evolved A-type giant star with a stellar classification of A0 III. It has around three times the mass of the Sun and 4.5 times the Sun's radius. The abundance of elements is similar to that in the Sun. It radiates 120 times the solar luminosity from its outer atmosphere at an effective temperature of 9,984 K. Alpha Sextantis is around 295 million years old with a projected rotational velocity of 21 km/s.

Beta Sextantis

Beta Sextantis, Latinized from β Sextantis, is a variable star in the equatorial constellation of Sextans. With an apparent visual magnitude of 5.07, it is faintly visible to the naked eye on a dark night. According to the Bortle scale, it can be viewed from brighter lit suburban skies. The distance to this star, based upon an annual parallax shift of 8.06 mas, is around 400 light years.

This star served as a primary standard in the MK spectral classification system with a stellar classification of B6 V, indicating that it is a B-type main sequence star. However, Houk and Swift (1999) list a classification of B5 IV/V, suggesting it may be transitioning into a subgiant star. It has served as a uvby photometric standard, but is also categorized as an Alpha2 Canum Venaticorum variable with a suspected period of 15.4 days. This lengthy a period conflicts with a relatively high projected rotational velocity of 85 km/s, leaving the explanation for the variance unresolved.


CR7 may refer to:

Cristiano Ronaldo, Portuguese international footballer, sometimes referred to as "CR7", in allusion to his initials and shirt number

Cosmos Redshift 7, a high-redshift galaxy, about 12.9 billion light-years from Earth

CR7, a postcode district in the CR postcode area of south London

CRJ700, the 70-seat version of the Canadair Regional Jet (CRJ)

CR-7(E), last high-end cassette deck by Nakamichi

Nike CR7, a Nike brand Cristiano Ronaldo line

Coma Filament

Coma Filament is a galaxy filament. The filament contains the Coma Supercluster of galaxies and forms a part of the CfA2 Great Wall.

Cristiano Ronaldo

Cristiano Ronaldo dos Santos Aveiro GOIH ComM (European Portuguese: [kɾiʃˈtjɐnu ʁoˈnaɫdu]; born 5 February 1985) is a Portuguese professional footballer who plays as a forward for Italian club Juventus and captains the Portugal national team. Often considered the best player in the world and regarded by many as one of the greatest players of all time, Ronaldo has a record-tying five Ballon d'Or awards, the most for a European player, and is the first player to win four European Golden Shoes. He has won 27 trophies in his career, including five league titles, five UEFA Champions League titles and one UEFA European Championship. A prolific goalscorer, Ronaldo holds the records for most official goals scored in Europe's top-five leagues (414), the UEFA Champions League (124), the UEFA European Championship (9), as well as those for most assists in the UEFA Champions League (34) and the UEFA European Championship (6). He has scored 700 senior career goals for club and country.

Born and raised on the Portuguese island of Madeira, Ronaldo was diagnosed with a racing heart at age 15. He underwent an operation to treat his condition, and began his senior club career playing for Sporting CP, before signing with Manchester United at age 18 in 2003. After winning his first trophy in England, the FA Cup, during his first season there, he helped United win three successive Premier League titles, a UEFA Champions League title, and a FIFA Club World Cup. By age 22, he had received Ballon d'Or and FIFA World Player of the Year nominations and at age 23, he won his first Ballon d'Or and FIFA World Player of the Year awards. In 2009, Ronaldo was the subject of, what was, at the time, the most expensive association football transfer when he moved from Manchester United to Real Madrid in a transfer worth €94 million (£80 million).

With Real Madrid, Ronaldo won 15 trophies, including two La Liga titles, two Copas del Rey, four UEFA Champions League titles, two UEFA Super Cups, and three FIFA Club World Cups. Real Madrid's all-time top goalscorer, Ronaldo scored a record 34 La Liga hat-tricks, including a record-tying eight hat-tricks in the 2014–15 season and is the only player to reach 30 goals in six consecutive La Liga seasons. After joining Madrid, Ronaldo finished runner-up for the Ballon d'Or three times, behind Lionel Messi, his perceived career rival, before winning back-to-back Ballons d'Or in 2013 and 2014. After winning the 2016 and 2017 Champions Leagues, Ronaldo secured back-to-back Ballons d'Or again in 2016 and 2017. A historic third consecutive Champions League followed, making Ronaldo the first player to win the trophy five times. In 2018, he signed for Juventus in a transfer worth an initial €100 million; the highest ever paid by an Italian club and the highest fee ever paid for a player over 30 years old.

A Portuguese international, Ronaldo was named the best Portuguese player of all time by the Portuguese Football Federation in 2015. He made his senior debut for Portugal in 2003 at age 18, and has since had over 150 caps, including appearing and scoring in eight major tournaments, becoming Portugal's most capped player and his country's all-time top goalscorer. He scored his first international goal at Euro 2004 and helped Portugal reach the final. He took over full captaincy in July 2008, leading Portugal to their first-ever triumph in a major tournament by winning Euro 2016, and received the Silver Boot as the second-highest goalscorer of the tournament, before becoming the highest European international goalscorer of all-time. One of the most marketable athletes in the world, he was ranked the world's highest-paid athlete by Forbes in 2016 and 2017, as well as the world's most famous athlete by ESPN in 2016, 2017 and 2018.

Delta Sextantis

Delta Sextantis (δ Sex, δ Sextantis) is a solitary star in the equatorial constellation of Sextans. With an annual parallax shift of 10.13 mas, it lies at a distance of around 322 light years from the Sun. This star is faintly visible to the naked eye, having an apparent visual magnitude of +5.25. According to the Bortle scale, that means it can be viewed from dark suburban skies.

This is a B-type main sequence star with a stellar classification of B9.5 V; just shy of being a cooler A-type star. It is estimated to have 2.6 times the Sun's mass and 2.3 times the radius of the Sun. It is 146 million years old, with a projected rotational velocity of 152 km/s. The star radiates 82 times the solar luminosity from its outer atmosphere at an effective temperature of 10,899 K.

Epsilon Sextantis

Epsilon Sextantis (ε Sex, ε Sextantis) is a solitary star in the equatorial constellation Sextans. With an apparent visual magnitude of 5.24, it is faintly visible to the naked eye on a dark night. The distance to this star, based upon an annual parallax shift of 16.86 mas, is about 193 light years.

This is an F-type subgiant star with a stellar classification of F0 IV. However, Malaroda (1975) gave a classification of F2 III, which would indicate a more evolved giant star. It is estimated to have nearly double the mass of the Sun. The star is around 1.1 billion years old and has a projected rotational velocity of 63.5 km/s.


A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter. The word galaxy is derived from the Greek galaxias (γαλαξίας), literally "milky", a reference to the Milky Way. Galaxies range in size from dwarfs with just a few hundred million (108) stars to giants with one hundred trillion (1014) stars, each orbiting its galaxy's center of mass.

Galaxies are categorized according to their visual morphology as elliptical, spiral, or irregular. Many galaxies are thought to have supermassive black holes at their centers. The Milky Way's central black hole, known as Sagittarius A*, has a mass four million times greater than the Sun. As of March 2016, GN-z11 is the oldest and most distant observed galaxy with a comoving distance of 32 billion light-years from Earth, and observed as it existed just 400 million years after the Big Bang.

Research released in 2016 revised the number of galaxies in the observable universe from a previous estimate of 200 billion (2×1011) to a suggested 2 trillion (2×1012) or more, containing more stars than all the grains of sand on planet Earth. Most of the galaxies are 1,000 to 100,000 parsecs in diameter (approximately 3000 to 300,000 light years) and separated by distances on the order of millions of parsecs (or megaparsecs). For comparison, the Milky Way has a diameter of at least 30,000 parsecs (100,000 LY) and is separated from the Andromeda Galaxy, its nearest large neighbor, by 780,000 parsecs (2.5 million LY).

The space between galaxies is filled with a tenuous gas (the intergalactic medium) having an average density of less than one atom per cubic meter. The majority of galaxies are gravitationally organized into groups, clusters, and superclusters. The Milky Way is part of the Local Group, which is dominated by it and the Andromeda Galaxy and is part of the Virgo Supercluster. At the largest scale, these associations are generally arranged into sheets and filaments surrounded by immense voids. The largest structure of galaxies yet recognised is a cluster of superclusters that has been named Laniakea, which contains the Virgo supercluster.

Gamma Sextantis

Gamma Sextantis, Latinized as γ Sextantis, is a binary star system in the equatorial constellation of Sextans. The combined apparent visual magnitude of the system is 5.05, which means it is faintly visible to the naked eye. The annual parallax shift is 11.75 mas, indicating a distance of around 280 light years.

The two components orbit each other with a period of 77.55 years and a high eccentricity of 0.691. The orbital plane is inclined by 145.1° to the line of sight from the Earth. With a visual magnitude of 5.6, the brighter component A is an A-type main sequence star with a stellar classification of A1 V. The fainter companion B has a classification of A4 V with a magnitude of 6.0. Their combined spectral matches a classification of A0/1 V.There is a magnitude 12.28 companion star C at an angular separation of 36.9 arc seconds along a position angle of 333°, as of 2000. This separation has increased from 30.0 arc seconds in 1834. The proper motion of this star differs from the Gamma Sextantis AB system, having components μα = −29 mas/yr and μδ = +5 mas/yr.

List of galaxies

The following is a list of notable galaxies.

There are about 51 galaxies in the Local Group (see list of nearest galaxies for a complete list), on the order of 100,000 in our Local Supercluster and an estimated number of about one to two trillion in all of the observable universe.

The discovery of the nature of galaxies as distinct from other nebulae (interstellar clouds) was made in the 1920s. The first attempts at systematic catalogues of galaxies were made in the 1960s, with the Catalogue of Galaxies and Clusters of Galaxies listing 29,418 galaxies and galaxy clusters, and with the Morphological Catalogue of Galaxies, a putatively complete list of galaxies with photographic magnitude above 15, listing 30,642. In the 1980s, the Lyons Groups of Galaxies listed 485 galaxy groups with 3,933 member galaxies. Galaxy Zoo is a project aiming at a more comprehensive list: launched in July 2007, it has classified over one million galaxy images from The Sloan Digital Sky Survey, The Hubble Space Telescope and the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey.There is no universal naming convention for galaxies, as they are mostly catalogued before it is established whether the object is or isn't a galaxy. Mostly they are identified by their celestial coordinates together with the name of the observing project (HUDF, SDSS, 3C, CFHQS, NGC/IC, etc.)

Lynx–Ursa Major Filament

Lynx–Ursa Major Filament (LUM Filament) is a galaxy filament.The filament is connected to and separate from the Lynx–Ursa Major Supercluster.


In astronomy, metallicity is used to describe the abundance of elements present in an object that are heavier than hydrogen or helium. Most of the physical matter in the Universe is in the form of hydrogen and helium, so astronomers use the word "metals" as a convenient short term for "all elements except hydrogen and helium". This usage is distinct from the usual physical definition of a solid metal. For example, stars and nebulae with relatively high abundances of carbon, nitrogen, oxygen, and neon are called "metal-rich" in astrophysical terms, even though those elements are non-metals in chemistry.

The presence of heavier elements hails from stellar nucleosynthesis, the theory that the majority of elements heavier than hydrogen and helium in the Universe ("metals", hereafter) are formed in the cores of stars as they evolve. Over time, stellar winds and supernovae deposit the metals into the surrounding environment, enriching the interstellar medium and providing recycling materials for the birth of new stars. It follows that older generations of stars, which formed in the metal-poor early Universe, generally have lower metallicities than those of younger generations, which formed in a more metal-rich Universe.

Observed changes in the chemical abundances of different types of stars, based on the spectral peculiarities that were later attributed to metallicity, led astronomer Walter Baade in 1944 to propose the existence of two different populations of stars.

These became commonly known as Population I (metal-rich) and Population II (metal-poor) stars. A third stellar population was introduced in 1978, known as Population III stars. These extremely metal-poor stars were theorised to have been the "first-born" stars created in the Universe.

Perseus–Pegasus Filament

Perseus–Pegasus Filament is a galaxy filament containing the Perseus-Pisces Supercluster and stretching for roughly a billion light years (or over 300/h Mpc). Currently, it is considered to be one of the largest known structures in the universe. This filament is adjacent to the Pisces–Cetus Supercluster Complex.


In physics, redshift is a phenomenon where electromagnetic radiation (such as light) from an object undergoes an increase in wavelength. Whether or not the radiation is visible, "redshift" means an increase in wavelength, equivalent to a decrease in wave frequency and photon energy, in accordance with, respectively, the wave and quantum theories of light.

Neither the emitted nor perceived light is necessarily red; instead, the term refers to the human perception of longer wavelengths as red, which is at the section of the visible spectrum with the longest wavelengths. Examples of redshifting are a gamma ray perceived as an X-ray, or initially visible light perceived as radio waves. The opposite of a redshift is a blueshift, where wavelengths shorten and energy increases. However, redshift is a more common term and sometimes blueshift is referred to as negative redshift.

There are three main causes of red (and blue shifts) in astronomy and cosmology:

Objects move apart (or closer together) in space. This is an example of the Doppler effect.

Space itself expands, causing objects to become separated without changing their positions in space. This is known as cosmological redshift. All sufficiently distant light sources (generally more than a few million light years away) show redshift corresponding to the rate of increase in their distance from Earth, known as Hubble's Law.

Gravitational redshift is a relativistic effect observed due to strong gravitational fields, which distort spacetime and exert a force on light and other particles.Knowledge of redshifts and blueshifts has been used to develop several terrestrial technologies such as Doppler radar and radar guns. Redshifts are also seen in the spectroscopic observations of astronomical objects. Its value is represented by the letter z.

A special relativistic redshift formula (and its classical approximation) can be used to calculate the redshift of a nearby object when spacetime is flat. However, in many contexts, such as black holes and Big Bang cosmology, redshifts must be calculated using general relativity. Special relativistic, gravitational, and cosmological redshifts can be understood under the umbrella of frame transformation laws. There exist other physical processes that can lead to a shift in the frequency of electromagnetic radiation, including scattering and optical effects; however, the resulting changes are distinguishable from true redshift and are not generally referred to as such (see section on physical optics and radiative transfer).


In the field of Big Bang theory, and cosmology, reionization is the process that caused the matter in the universe to reionize after the lapse of the "dark ages".

Reionization is the second of two major phase transitions of gas in the universe. While the majority of baryonic matter in the universe is in the form of hydrogen and helium, reionization usually refers strictly to the reionization of hydrogen, the element.

It's believed that the primordial helium also experienced the same phase of reionization changes, but at different points in the history of the universe. This is usually referred to as helium reionization.


Sextans is a minor equatorial constellation which was introduced in 1687 by Johannes Hevelius. Its name is Latin for the astronomical sextant, an instrument that Hevelius made frequent use of in his observations.


A star is type of astronomical object consisting of a luminous spheroid of plasma held together by its own gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye from Earth during the night, appearing as a multitude of fixed luminous points in the sky due to their immense distance from Earth. Historically, the most prominent stars were grouped into constellations and asterisms, the brightest of which gained proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. However, most of the estimated 300 sextillion (3×1023) stars in the Universe are invisible to the naked eye from Earth, including all stars outside our galaxy, the Milky Way.

For at least a portion of its life, a star shines due to thermonuclear fusion of hydrogen into helium in its core, releasing energy that traverses the star's interior and then radiates into outer space. Almost all naturally occurring elements heavier than helium are created by stellar nucleosynthesis during the star's lifetime, and for some stars by supernova nucleosynthesis when it explodes. Near the end of its life, a star can also contain degenerate matter. Astronomers can determine the mass, age, metallicity (chemical composition), and many other properties of a star by observing its motion through space, its luminosity, and spectrum respectively. The total mass of a star is the main factor that determines its evolution and eventual fate. Other characteristics of a star, including diameter and temperature, change over its life, while the star's environment affects its rotation and movement. A plot of the temperature of many stars against their luminosities produces a plot known as a Hertzsprung–Russell diagram (H–R diagram). Plotting a particular star on that diagram allows the age and evolutionary state of that star to be determined.

A star's life begins with the gravitational collapse of a gaseous nebula of material composed primarily of hydrogen, along with helium and trace amounts of heavier elements. When the stellar core is sufficiently dense, hydrogen becomes steadily converted into helium through nuclear fusion, releasing energy in the process. The remainder of the star's interior carries energy away from the core through a combination of radiative and convective heat transfer processes. The star's internal pressure prevents it from collapsing further under its own gravity. A star with mass greater than 0.4 times the Sun's will expand to become a red giant when the hydrogen fuel in its core is exhausted. In some cases, it will fuse heavier elements at the core or in shells around the core. As the star expands it throws a part of its mass, enriched with those heavier elements, into the interstellar environment, to be recycled later as new stars. Meanwhile, the core becomes a stellar remnant: a white dwarf, a neutron star, or if it is sufficiently massive a black hole.

Binary and multi-star systems consist of two or more stars that are gravitationally bound and generally move around each other in stable orbits. When two such stars have a relatively close orbit, their gravitational interaction can have a significant impact on their evolution. Stars can form part of a much larger gravitationally bound structure, such as a star cluster or a galaxy.

Stellar population

During 1944, Walter Baade categorized groups of stars within the Milky Way into stellar populations. He noticed that bluer stars were strongly associated with the spiral arms and yellow stars dominated near the central galactic bulge and within globular star clusters. Two main divisions were defined as Population I and Population II, with another newer division called Population III added in 1978, which are often simply abbreviated as Pop I, II or III.

Between the population types, significant differences were found with their individual observed stellar spectra. These were later shown to be very important, and were possibly related to star formation, observed kinematics, stellar age, and even galaxy evolution in both spiral or elliptical galaxies. These three simple population classes usefully divided stars by their chemical composition or metallicity, whose small proportion of chemical abundance consists of heavier elements against the far more abundant hydrogen and helium.By definition, each population group shows the trend where decreasing metal content indicates increasing age of stars. Hence, the first stars in the universe (very low metal content) were deemed Population III, old stars (low metallicity) as Population II, and recent stars (high metallicity) as Population I.

Ursa Major Filament

Ursa Major Filament is a galaxy filament. The filament is connected to the CfA Homunculus, a portion of the filament forms a portion of the "leg" of the Homunculus.

Active nuclei
Energetic galaxies
Low activity
See also
Stars of Sextans

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