The Archeops gondola being launched
|Alternative names||ARCHEOPS |
|Wavelength||143, 217, 353, 545 GHz (2.096, 1.382, 0.849, 0.550 mm)|
|First light||1999 |
|Telescope style|| Cosmic microwave background experiment |
|Angular resolution||15 minute of arc |
Archeops was a balloon-borne instrument dedicated to measuring the Cosmic microwave background (CMB) temperature anisotropies. The study of this radiation is essential to obtain precise information on the evolution of the Universe: density, Hubble constant, age of the Universe, etc. To achieve this goal, measurements were done with devices cooled down at 100mK temperature placed at the focus of a warm telescope. To avoid atmospheric disturbance the whole apparatus is placed on a gondola below a helium balloon that reaches 40 km altitude.
The cosmic microwave background is electromagnetic radiation as a remnant from an early stage of the universe in Big Bang cosmology. In older literature, the CMB is also variously known as cosmic microwave background radiation (CMBR) or "relic radiation". The CMB is a faint cosmic background radiation filling all space that is an important source of data on the early universe because it is the oldest electromagnetic radiation in the universe, dating to the epoch of recombination. With a traditional optical telescope, the space between stars and galaxies is completely dark. However, a sufficiently sensitive radio telescope shows a faint background noise, or glow, almost isotropic, that is not associated with any star, galaxy, or other object. This glow is strongest in the microwave region of the radio spectrum. The accidental discovery of the CMB in 1964 by American radio astronomers Arno Penzias and Robert Wilson was the culmination of work initiated in the 1940s, and earned the discoverers the 1978 Nobel Prize in Physics.
TheUniverse is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. While the spatial size of the entire Universe is unknown, it is possible to measure the size of the observable universe. In various multiverse hypotheses, auniverse is one of many causally disconnected constituent parts of a larger multiverse, which itself comprises all of space and time and its contents, or those with differing physical constants, or both.
Archeops has four bands in the millimeter domain (143, 217, 353 and 545 GHz) with a high angular resolution (about 15 arcminutes) in order to constrain small anisotropy scales, as well as a large sky coverage fraction (30%) in order to minimize the intrinsic cosmic variance.
The instrument was designed by adapting concepts put forward for the High Frequency Instrument of Planck surveyor (Planck-HFI) and using balloon-borne constraints.Namely, it consists of an open 3He-4He dilution cryostat cooling spiderweb-type bolometers at 100 mK; cold individual optics with horns at different temperature stages (0.1, 1.6, 10 K) and an off-axis Gregorian telescope.
A bolometer is a device for measuring the power of incident electromagnetic radiation via the heating of a material with a temperature-dependent electrical resistance. It was invented in 1878 by the American astronomer Samuel Pierpont Langley.
The Gregorian telescope is a type of reflecting telescope designed by Scottish mathematician and astronomer James Gregory in the 17th century, and first built in 1673 by Robert Hooke. James Gregory was a contemporary of Isaac Newton, both often worked simultaneously on similar projects. Gregory's design was published in 1663 and pre-dates the first practical reflecting telescope, the Newtonian telescope, built by Sir Isaac Newton in 1668. However, Gregory's design was only a theoretical description and he never actually constructed the telescope. It was not successfully built until five years after Newton's first reflecting telescope.
The CMB signal is measured by the 143 and 217 GHz detectors while interstellar dust emission and atmospheric emission are monitored with the 353 (polarized) and 545 GHz detectors. The whole instrument is bafﬂed so as to avoid stray radiation from the Earth and the balloon.
To cover as far as 30% of the sky, the payload was spinning mostly above the atmosphere, scanning the sky in circles with a fixed elevation of roughly 41 degrees. The gondola, at a ﬂoat altitude above 32 km, spins across the sky at a rate of 2 rpm which, combined with the Earth rotation, produces a well sampled sky at each frequency.
Archeops flew for the first time in Trapani (Sicily) with four–hours integration time. Then, the upgraded instrument was launched three times from the Esrange base near Kiruna (Sweden) by the CNES during 2 consecutive Winter seasons (2001 and 2002). The last and best ﬂight on Feb. 7th, 2002 yields 12.5 hours of CMB–type data (at ceiling altitude and by night) from a 19–hours total. The balloon landed in Siberia and it was recovered (with its precious data recorded on–board) by a Franco–Russian team with –40 deg.C. weather.
Archeops has linked, for the first time and before WMAP, the large angular scales (previously measured by COBE) to the first acoustic peak region.
The Cosmic Background Explorer, also referred to as Explorer 66, was a satellite dedicated to cosmology, which operated from 1989 to 1993. Its goals were to investigate the cosmic microwave background radiation (CMB) of the universe and provide measurements that would help shape our understanding of the cosmos.
From its results, inflation motivated cosmologies have been reinforced with a flat Universe (total energy density Ωtot = 1 within 3%). When combined with complementary cosmological datasets regarding the value of Hubble's constant, Archeops gives constraints on the dark energy density and the baryonic density in very good agreement with other independent estimations based on supernovae measurements and big bang nucleosynthesis.
Archeops has given the first polarized maps of the galactic dust emission with this resolution.
Messier 21 or M21, also designated NGC 6531, is an open cluster of stars in the constellation of Sagittarius. It was discovered and catalogued by Charles Messier on June 5, 1764. This cluster is relatively young and tightly packed. A few blue giant stars have been identified in the cluster, but Messier 21 is composed mainly of small dim stars. With a magnitude of 6.5, M21 is not visible to the naked eye; however, with the smallest binoculars it can be easily spotted on a dark night. The cluster is positioned near the Trifid nebula, but is not associated with that nebulosity. It forms part of the Sagittarius OB1 association.
In astronomy and observational cosmology, The BOOMERanG experiment was an experiment which measured the cosmic microwave background radiation of a part of the sky during three sub-orbital (high-altitude) balloon flights. It was the first experiment to make large, high-fidelity images of the CMB temperature anisotropies, and is best known for the discovery in 2000 that the geometry of the universe is close to flat, with similar results from the competing MAXIMA experiment.
Omicron Scorpii is a star in the zodiac constellation of Scorpius. With an apparent visual magnitude of +4.57, it is visible to the naked eye. Parallax measurements indicate a distance of roughly 900 light years. It is located in the proximity of the Rho Ophiuchi dark cloud.
Delta Antliae is the Bayer designation for a binary star system in the southern constellation of Antlia. The combined apparent visual magnitude of the system is +5.57, allowing it to be viewed from the suburbs with the naked eye. Judging by the parallax shift of this system, it is located at a distance of 450 ± 10 light-years from Earth. The system is reduced in magnitude by 0.03 due to extinction caused by intervening gas and dust.
Eta Arietis is the Bayer designation for a star in the northern constellation of Aries. It is dimly visible to the naked eye with an apparent visual magnitude of 5.231. With an annual parallax shift of 34.64 mas, the distance to this star is approximately 94.2 light-years.
Sigma Arietis, Latinized from σ Arietis, is the Bayer designation for a star in the northern constellation of Aries. It has an apparent visual magnitude of +5.52, which is bright enough for the star to be seen with the naked eye from dark suburban skies. Based upon an annual measured parallax shift of 6.60 ± 0.32 mas, it is approximately 494 light-years distant from the Earth.
38 Arietis is a variable star in the northern constellation of Aries. 38 Arietis is the Flamsteed designation. It was once designated 88 Ceti, forming part of the neighboring constellation of Cetus. With an apparent visual magnitude of +5.18, it is bright enough to be viewed with the naked eye. The measured annual parallax shift of 27.52 mas is equivalent to a distance of approximately 119 light-years from Earth.
Nu1 Boötis (ν1 Boötis) is an orange-hued star in the northern constellation of Boötes. It has an apparent visual magnitude of +5.02, which indicates the star is faintly visible to the naked eye. Based upon an annual parallax shift of 7.59 mas as seen from Earth, it is located roughly 430 light years distant from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction of 0.13 due to interstellar dust.
58 Eridani is a main-sequence star in the constellation Eridanus. It is considered a solar analogue, which means it has similar physical properties to the Sun. The star has a relatively high proper motion across the sky, and it is located about 43 light years distant. It is a probable member of the IC 2391 moving group of stars that share a common motion through space.
14 Eridani is a star in the Eridanus constellation. It has an apparent visual magnitude of 6.143 and is moving closer to the Sun with a radial velocity of around −5 km/s. The measured annual parallax shift is 29.26 mas, which provides an estimated distance of about 111 light years. Proper motion studies indicate that this is an astrometric binary. The visible component has a stellar classification of F5 V Fe−0.7 CH−0.5, which indicates it has the spectrum of an F-type main-sequence star with underabundances of iron and methylidyne. The system has been detected as a source of X-ray emission.
HD 221776 is a double star in the northern constellation of Andromeda. With an apparent visual magnitude of 6.18,, it is viewable by the naked eye user very favourable conditions. The most luminous component has a spectral classification K5III, meaning that it's an orange giant star that has evolved off the main sequence. An infrared excess has been detected around this star, indicating the star is associated with a cloud of dust particles.
S Persei is a red supergiant located near the Double Cluster in Perseus, north of the cluster NGC 869. It is a member of the Perseus OB1 association and one of the largest known stars. It is also a semiregular variable, a star whose variations are less regular than those of Mira variables.
NGC 2281 is an open cluster in the constellation Auriga.
HD 44594 is a star in the southern constellation Puppis. It has an apparent visual magnitude of 6.64, so it can be seen with the naked eye from the southern hemisphere under good viewing conditions. Based upon parallax measurements, it is located at a distance of about 82 light-years from the Earth, giving it an absolute magnitude of 4.56.
Rho Draconis is a solitary star in the northern circumpolar constellation of Draco. It is faintly visible to the naked eye with an apparent visual magnitude is 4.52. Based upon an annual parallax shift of 7.61 mas as measured from Earth, it is located around 429 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.027 due to interstellar dust.
26 Vulpeculae is a close binary star system in the northern constellation of Vulpecula, around 644 light years away from the Sun. It is a challenge to view with the naked eye, having an apparent visual magnitude of 6.40. The star is moving closer to the Earth with a heliocentric radial velocity of −63 km/s, and is expected to come within 225 light-years in around 2.6 million years.
Tau6 Eridani is a star in the constellation Eridanus. It has an apparent visual magnitude of 4.22, which is bright enough to be seen with the naked eye. Based upon parallax measurements, the distance to this star is around 57.5 light years.
The "Axis of Evil" is a name given to an anomaly in astronomical observations of the Cosmic Microwave Background (CMB). The anomaly appears to give the plane of the Solar System and hence the location of Earth a greater significance than might be expected by chance – a result which appears to run counter to expectations from the Copernican Principle.
HD 219623 is the Henry Draper Catalogue designation for a solitary star in the northern circumpolar constellation of Cassiopeia. It has an apparent visual magnitude of 5.59, which lies in the brightness range that is visible to the naked eye. According to the Bortle scale, it can be observed from dark suburban skies. Parallax measurements made by the Hipparcos spacecraft place it at an estimated distance of around 66.9 light years. It has a relatively high proper motion, advancing 262 milliarcseconds per year across the celestial sphere.
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