MACS J1149 Lensed Star 1, also known as Icarus,Other names include ''LS1'', ''MACS J1149 LS1'', ''MACS J1149 Lensed Star 1 (LS1)'' and ''MACS J1149+2223 Lensed Star 1'' is a

blue supergiant A blue supergiant (BSG) is a hot, luminous star, often referred to as an OB supergiant. They have luminosity class I and spectral class B9 or earlier. Blue supergiants are found towards the top left of the Hertzsprung–Russell diagram, above an ...

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

observed through a gravitational lens. It is the second most distant individual star to have been detected so far (second only to

WHL0137-LS WHL0137-LS, also known as Earendel, is a star in the constellation of Cetus. Discovered in 2022 by the Hubble Space Telescope, it is the earliest and most distant known star, at a comoving distance of . The previous furthest known star, MACS J ...

, a.k.a. Earendel, as of March 2022), at approximately 14 billion

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s 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 ...

(

redshift In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and simultaneous increase in f ...

z=1.49; comoving distance of 14.4 billion light-years;

lookback time Before Present (BP) years, or "years before present", is a time scale used mainly in archaeology, geology and other scientific disciplines to specify when events occurred relative to the origin of practical radiocarbon dating in the 1950s. Becau ...

of 9.34 billion years). Light from the

was emitted 4.4 billion years after the

Big Bang The Big Bang event is a physical theory that describes how the universe expanded from an initial state of high density and temperature. Various cosmological models of the Big Bang explain the evolution of the observable universe from the ...

. According to co-discoverer Patrick Kelly, the star is at least a hundred times more distant than the next-farthest non-

supernova A supernova is a powerful and luminous explosion of a star. It has the plural form supernovae or supernovas, and is abbreviated SN or SNe. This transient astronomical event occurs during the last evolutionary stages of a massive star or when ...

star observed,

SDSS J1229+1122 SDSS J1229+1122 (SDSS J122952.66+112227.8) is a blue supergiant O-type star in the tail of dwarf irregular galaxy IC 3418. It illuminates a nebula clump of gas, and was discovered from the spectrum of the illumination source. The clump ...

, and is the first magnified individual star seen.

History

NASA-Icarus-BlueSuperGiantSpectrum-Hubble-20180402

In April and May 2018, the star was found in the course of studying the supernova

SN Refsdal SN Refsdal is the first detected multiply-lensed supernova, visible within the field of the galaxy cluster MACS J1149+2223. It was given its nickname in honor of the Norwegian astrophysicist Sjur Refsdal, who, in 1964, first proposed using time ...

with 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 versa ...

. Astronomer Patrick Kelly of the

University of Minnesota The University of Minnesota, formally the University of Minnesota, Twin Cities, (UMN Twin Cities, the U of M, or Minnesota) is a public university, public Land-grant university, land-grant research university in the Minneapolis–Saint Paul, Tw ...

is the lead author of the finding, published in the journal '' Nature Astronomy''. While astronomers had been collecting images of this supernova from 2004 onward, they recently discovered a point source that had appeared in their 2013 images, and become much brighter by 2016. They determined that the point source was a solitary star being magnified more than 2,000 times by

gravitational lensing A gravitational lens is a distribution of matter (such as a galaxy cluster, cluster of galaxies) between a distant light source and an observer that is capable of bending the light from the source as the light travels toward the observer. This ...

. The light from LS1 was magnified not only by the huge total mass of the galaxy cluster

MACS J1149+2223 Macs or MACS may refer to: *a Mac computer, a nickname for the Macintosh brand *macs (short story), "macs" (short story), by Terry Bisson *Magellanic Catalogue of Stars, a catalogue of positions for stars covering large areas around the Large and S ...

—located 5 billion light-years away—but also transiently by another compact object of about three

solar mass The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass ...

es within the galaxy cluster itself that passed through the line of sight, an effect known as gravitational microlensing. The galaxy cluster magnification is probably a factor of 600, while the microlensing event, which peaked in May 2016, brightened the image by an additional factor of ~4. There was a second peak near the brightness curve maximum, which may indicate the star was

binary Binary may refer to: Science and technology Mathematics * Binary number, a representation of numbers using only two digits (0 and 1) * Binary function, a function that takes two arguments * Binary operation, a mathematical operation that t ...

. The microlensing body may have been a star or a black hole in the cluster. Continuous monitoring of the star ''Icarus'' may one day rule out the possibility that primordial black holes constitute a sizable fraction of

dark matter Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe. Dark matter is called "dark" because it does not appear to interact with the electromagnetic field, which means it does not ab ...

. Normally, the only astronomical objects that can be detected at this range would be either whole galaxies,

quasar A quasar is an extremely Luminosity, luminous active galactic nucleus (AGN). It is pronounced , and sometimes known as a quasi-stellar object, abbreviated QSO. This emission from a galaxy nucleus is powered by a supermassive black hole with a m ...

s, or

s, but the light from the star was magnified by the lensing effect. They determined the light was from a stable star, not a

, as its temperature did not fluctuate; the temperature also allowed them to catalog the star as a

. Because the visible light is the redshifted ultraviolet tail, the star does not appear blue to us but reddish or pink. The light observed from the star was emitted when the universe was about 30% of its current age of 13.8 billion years. Kelly suggested that similar microlensing discoveries could help them identify the earliest stars in the universe.

Name

The formal name MACS J1149 is a reference to

MAssive Cluster Survey The MAssive Cluster Survey (MACS) compiled and characterized a sample of very X-ray luminous (and thus, by inference, massive), distant clusters of galaxies. The sample comprises 124 spectroscopically confirmed clusters at 0.3 < z < 0.7. Candidate ...

and the star's coordinates in the

J2000 In astronomy, an epoch or reference epoch is a instant, moment in time used as a reference point for some time-varying astronomical quantity. It is useful for the celestial coordinates or orbital elements of a Astronomical object, celestial body, ...

astronomical epoch. While Kelly had wanted to name the star ''Warhol'', alluding to

Andy Warhol Andy Warhol (; born Andrew Warhola Jr.; August 6, 1928 – February 22, 1987) was an American visual artist, film director, and producer who was a leading figure in the visual art movement known as pop art. His works explore the relationsh ...

's notion of having

15 minutes of fame Fifteen or 15 may refer to: *15 (number), the natural number following 14 and preceding 16 *one of the years 15 BC, AD 15, 1915, 2015 Music *Fifteen (band), a punk rock band Albums * ''15'' (Buckcherry album), 2005 * ''15'' (Ani Lorak alb ...

, the team ended up naming the star ''Icarus'' based on the Greek mythological figure.

Astrophysical implications

The discovery shows that astronomers can study the oldest stars in background

galaxies A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. ...

of the 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. Acc ...

by combining the strong gravitational lensing effect from galaxy clusters with gravitational microlensing events caused by compact objects in these galaxy clusters. By using these events, astronomers can study and test some models about dark matter in galaxy clusters and observe high energy events (supernovae,

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 ...

s) in young galaxies.

Notes

References

External links

Hubble Discovers Supernova Split by Cosmic Lens
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NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

(2017)
View of SN Refsdal
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National Geographic Society The National Geographic Society (NGS), headquartered in Washington, D.C., United States, is one of the largest non-profit scientific and educational organizations in the world. Founded in 1888, its interests include geography, archaeology, and ...

(2015)
Images of SN Refsdal
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HubbleSite The Space Telescope Science Institute (STScI) is the science operations center for the Hubble Space Telescope (HST), science operations and mission operations center for the James Webb Space Telescope (JWST), and science operations center for the ...