Астрофизика, раздел астрономии, изучающий физические явления, происходящие в небесных телах, их системах и в космическом пространств - shikardos.ru o_O
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Astrophysics

  1. Read and translate the definitions of astrophysics both into Russian and into English. Which one do you like more?

Астрофизика, раздел астрономии, изучающий физические явления, происходящие в небесных телах, их системах и в космическом пространстве, а также химические процессы в них. Астрофизика включает разработку методов получения информации о физических явлениях во Вселенной, сбор этой информации (главным образом путём астрономических наблюдений), её научную обработку и теоретическое обобщение. Теоретическая астрофизика, занимаясь обобщением и объяснением фактических данных, полученных наблюдательной астрофизикой, пользуется законами и методами теоретической физики. Совокупность методов наблюдательной астрофизика часто называют практической астрофизикой.

Astrophysics (Greek: Astro – αστρον – meaning "star", and Greek: physisφύσις – meaning "nature") is the branch of astronomy that deals with the physics of the universe, including the physical properties (luminosity, density, temperature, and chemical composition) of celestial objects such as galaxies, stars, planets, exoplanets, and the interstellar medium, as well as their interactions. The study of cosmology addresses questions of astrophysics at scales much larger than the size of particular gravitationally-bound objects in the universe.



  1. Can you translate the following words and explain their meaning?

luminosity, interstellar medium, interferometry, spectroscopy, photometry, polarimetry.

  1. Match English word combinations from A with their Russian equivalent from B.

A. the cosmic microwave background radiation, to penetrate the Earth's atmosphere, the highest possible image quality, astrophysical observations, interstellar gas, Hertzsprung-Russell diagram, pulsar deceleration, space-based telescopes, area of study, to be studied at infrared frequencies, electromagnetic spectrum, very high energy particles, dust clouds, to be detected at some frequencies, chemical spectra, to vary in time scale.

B. высокоэнергетические частицы, угасание/замедление пульсаров, электромагнитный спектр, различаться по продолжительности, реликтовое излучение, сталкиваться с земной атмосферой, межзвёздный газ, пылевые облака, область изучения, быть обнаруженным на тех или иных частотах, данные в астрофизике, химическое строение, изучать на ифракрасных частотах, космические телескопы, диаграмма Герцшпрунга — Рассела, максимально чёткое изображение.

  1. Read the text and answer the following questions:

  1. What does radio astronomy study?

  2. What is the oldest kind of astronomy? Why?

  3. What is infrared astronomy?

  4. What instruments are used in optic astronomy?

  5. What is the difference in observational time scale of e.g. optical astronomy and radio astronomy?

  6. How do ultraviolet, x-ray and gamma ray astronomy differ fom other kinds of astronomical observations?

Observational astrophysics

The majority of astrophysical observations are made using the electromagnetic spectrum.

Radio astronomy studies radiation with a wavelength greater than a few millimeters. Example areas of study are radio waves, usually emitted by cold objects such as interstellar gas and dust clouds; the cosmic microwave background radiation which is the redshifted light from the Big Bang; Pulsars, which were first detected at microwave frequencies. The study of these waves requires very large radio telescopes.

Infrared astronomy studies radiation with a wavelength that is too long to be visible to the naked eye but is shorter than radio waves. Infrared observations are usually made with telescopes similar to the familiar optical telescopes. Objects colder than stars (such as planets) are normally studied at infrared frequencies.

Optical astronomy is the oldest kind of astronomy. Telescopes paired with a charge-coupled device or spectroscopes are the most common instruments used. The Earth's atmosphere interferes somewhat with optical observations, so adaptive optics and space telescopes are used to obtain the highest possible image quality. In this wavelength range, stars are highly visible, and many chemical spectra can be observed to study the chemical composition of stars, galaxies and nebulae.

Ultraviolet, X-ray and gamma ray astronomy study very energetic processes such as binary pulsars, black holes, magnetars, and many others. These kinds of radiation do not penetrate the Earth's atmosphere well. There are two methods in use to observe this part of the electromagnetic spectrum—space-based telescopes and ground-based imaging air Cherenkov telescopes (IACT). Examples of Observatories of the first type are RXTE, the Chandra X-ray Observatory and the Compton Gamma Ray Observatory. Examples of IACTs are the High Energy Stereoscopic System (H.E.S.S.) and the MAGIC telescope.

Other than electromagnetic radiation, few things may be observed from the Earth that originate from great distances. A few gravitational wave observatories have been constructed, but gravitational waves are extremely difficult to detect. Neutrino observatories have also been built, primarily to study our Sun. Cosmic rays consisting of very high energy particles can be observed hitting the Earth's atmosphere.

Observations can also vary in their time scale. Most optical observations take minutes to hours, so phenomena that change faster than this cannot readily be observed. However, historical data on some objects is available spanning centuries or millennia. On the other hand, radio observations may look at events on a millisecond timescale (millisecond pulsars) or combine years of data (pulsar deceleration studies). The information obtained from these different timescales is very different.

The study of our own Sun has a special place in observational astrophysics. Due to the tremendous distance of all other stars, the Sun can be observed in a kind of detail unparalleled by any other star. Our understanding of our own sun serves as a guide to our understanding of other stars.

The topic of how stars change, or stellar evolution, is often modeled by placing the varieties of star types in their respective positions on the Hertzsprung-Russell diagram, which can be viewed as representing the state of a stellar object, from birth to destruction.



  1. Fill in the gaps with the words given below in mixed order.

Studies, is conducted, the distance, radio interferometry, compelling, a subfield, referred to, include, was made through, observed, different, resolution.

Radio astronomy is of astronomy that celestial objects at radio frequencies. The initial detection of radio waves from an astronomical object was made in the 1930s, when Karl Jansky radiation coming from the Milky Way. Subsequent observations have identified a number of sources of radio emission. These stars and galaxies, as well as entirely new classes of objects, such as radio galaxies, quasars, pulsars, and masers. The discovery of the cosmic microwave background radiation, which provided evidence for the Big Bang, radio astronomy.

Radio astronomy using large radio antennae as radio telescopes, that are either used singularly, or with multiple linked telescopes utilizing the techniques of and aperture synthesis. The use of interferometry allows radio astronomy to achieve high angular , as the resolving power of an interferometer is set by between its components, rather than the size of its components.



  1. Write down the names of the scientists, who made contributions into the development of astrophysics and retell the history of astrophysics according to your outline.

Although astronomy is as ancient as recorded history itself, it was long separated from the study of physics. In the Aristotelian worldview, the celestial world tended towards perfection—bodies in the sky seemed to be perfect spheres moving in perfectly circular orbits—while the earthly world seemed destined to imperfection; these two realms were not seen as related.

Aristarchus of Samos (c. 310–250 BC) first put forward the notion that the motions of the celestial bodies could be explained by assuming that the Earth and all the other planets in the Solar System orbited the Sun. Unfortunately, in the geocentric world of the time, Aristarchus's heliocentric theory was deemed outlandish and heretical. For centuries, the apparently common-sense view that the Sun and other planets went round the Earth nearly went unquestioned until the development of Copernican heliocentrism in the 16th century AD. This was due to the dominance of the geocentric model developed by Ptolemy (c. 83-161 AD), a Hellenized astronomer from Roman Egypt, in his Almagest treatise.

The only known supporter of Aristarchus was Seleucus of Seleucia, a Babylonian astronomer who is said to have proved heliocentrism through reasoning in the 2nd century BC. This may have involved the phenomenon of tides, which he correctly theorized to be caused by attraction to the Moon and notes that the height of the tides depends on the Moon's position relative to the Sun. Alternatively, he may have determined the constants of a geometric model for the heliocentric theory and developed methods to compute planetary positions using this model, possibly using early trigonometric methods that were available in his time, much like Copernicus. B. L. van der Waerden has interpreted the planetary models developed by Aryabhata (476-550), an Indian astronomer, and Abu Ma'shar al-Balkhi (787-886), a Persian astronomer, to be heliocentric models but this view has been strongly disputed by others.

In the 9th century AD, the Persian physicist and astronomer, Ja'far Muhammad ibn Mūsā ibn Shākir, hypothesized that the heavenly bodies and celestial spheres are subject to the same laws of physics as Earth, unlike the ancients who believed that the celestial spheres followed their own set of physical laws different from that of Earth. He also proposed that there is a force of attraction between "heavenly bodies", vaguely foreshadowing the law of gravity.

In the early 11th century, the Arabic Ibn al-Haytham (Alhazen) wrote the Maqala fi daw al-qamar (On the Light of the Moon) some time before 1021. This was the first successful attempt at combining mathematical astronomy with physics, and the earliest attempt at applying the experimental method to astronomy and astrophysics. He disproved the universally held opinion that the moon reflects sunlight like a mirror and correctly concluded that it "emits light from those portions of its surface which the sun's light strikes." In order to prove that "light is emitted from every point of the moon's illuminated surface," he built an "ingenious experimental device." Ibn al-Haytham had "formulated a clear conception of the relationship between an ideal mathematical model and the complex of observable phenomena; in particular, he was the first to make a systematic use of the method of varying the experimental conditions in a constant and uniform manner, in an experiment showing that the intensity of the light-spot formed by the projection of the moonlight through two small apertures onto a screen diminishes constantly as one of the apertures is gradually blocked up."

In the 14th century, Ibn al-Shatir produced the first model of lunar motion which matched physical observations, and which was later used by Copernicus. In the 13th to 15th centuries, Tusi and Ali Qushji provided the earliest empirical evidence for the Earth's rotation, using the phenomena of comets to refute Ptolemy's claim that a stationary Earth can be determined through observation. Kuşçu further rejected Aristotelian physics and natural philosophy, allowing astronomy and physics to become empirical and mathematical instead of philosophical. In the early 16th century, the debate on the Earth's motion was continued by Al-Birjandi (d. 1528), who in his analysis of what might occur if the Earth were rotating, develops a hypothesis similar to Galileo Galilei's notion of "circular inertia", which he described in the following observational test:

The small or large rock will fall to the Earth along the path of a line that is perpendicular to the plane (sath) of the horizon; this is witnessed by experience (tajriba). And this perpendicular is away from the tangent point of the Earth’s sphere and the plane of the perceived (hissi) horizon. This point moves with the motion of the Earth and thus there will be no difference in place of fall of the two rocks.

After heliocentrism was revived by Nicolaus Copernicus in the 16th century, Galileo Galilei discovered the four brightest moons of Jupiter in 1609, and documented their orbits about that planet, which contradicted the geocentric dogma of the Catholic Church of his time, and escaped serious punishment only by maintaining that his astronomy was a work of mathematics, not of natural philosophy (physics), and therefore purely abstract.

The availability of accurate observational data (mainly from the observatory of Tycho Brahe) led to research into theoretical explanations for the observed behavior. At first, only empirical rules were discovered, such as Kepler's laws of planetary motion, discovered at the start of the 17th century. Later that century, Isaac Newton bridged the gap between Kepler's laws and Galileo's dynamics, discovering that the same laws that rule the dynamics of objects on Earth rule the motion of planets and the moon. Celestial mechanics, the application of Newtonian gravity and Newton's laws to explain Kepler's laws of planetary motion, was the first unification of astronomy and physics.

After Isaac Newton published his book, Philosophiæ Naturalis Principia Mathematica, maritime navigation was transformed. Starting around 1670, the entire world was measured using essentially modern latitude instruments and the best available clocks. The needs of navigation provided a drive for progressively more accurate astronomical observations and instruments, providing a background for ever more available data for scientists.

At the end of the 19th century, it was discovered that, when decomposing the light from the Sun, a multitude of spectral lines were observed (regions where there was less or no light). Experiments with hot gases showed that the same lines could be observed in the spectra of gases, specific lines corresponding to unique chemical elements. In this way it was proved that the chemical elements found in the Sun (chiefly hydrogen) were also found on Earth. Indeed, the element helium was first discovered in the spectrum of the Sun and only later on Earth, hence its name. During the 20th century, spectroscopy (the study of these spectral lines) advanced, particularly as a result of the advent of quantum physics that was necessary to understand the astronomical and experimental observations.


  1. Translate at sight.

Gamma-ray bursts (GRBs) are the most powerful blasts in the Universe, and are thought to be created in the deaths of the most massive stars. These brief flashes of gamma radiation are picked up by dedicated satellites which then send out an alert to the astronomers who study them. The dual discovery of a gamma-ray burst and supernova is remarkable in its high energy properties: the X-ray radiation reveals the explosion breaking out of the star. This event provides a much needed confirmation of a phenomenon glimpsed only once previously, supporting the theory that GRBs are indeed linked with the destruction of massive stars.

  1. Translate the text into English.

Диаграмма Герцшпрунга — Рассела показывает зависимость между абсолютной звёздной величиной, светимостью, спектральным классом и температурой поверхности звезды. Неожиданным является тот факт, что звёзды на этой диаграмме располагаются не случайно, а образуют хорошо различимые участки.

Данная диаграмма была предложена в 1910 году независимо Эйнаром Герцшпрунгом (Дания) и Генри Расселом (США). Она используется для классификации звёзд и соответствует современным представлениям о звёздной эволюции и даёт возможность (хотя и не очень точно) найти абсолютную величину по спектральному классу.

Около 90 % звёзд находятся на главной последовательности. Их светимость обусловлена ядерными реакциями превращения водорода в гелий. Выделяется также несколько ветвей проэволюционировавших звёзд — гигантов, в которых происходит горение гелия и более тяжёлых элементов. В левой нижней части диаграммы находятся полностью проэволюционировавшие белые карлики.


  1. Read the text, write down the important facts and discoveries. Retell the text according to your outline.

The Sun is the star at the center of the Solar System. It has a diameter of about 1,392,000 km, about 109 times that of Earth, and its mass (about 2×1030 kilograms, 330,000 times that of Earth) accounts for about 99.86% of the total mass of the Solar System. About three quarters of the Sun's mass consists of hydrogen, while the rest is mostly helium. Less than 2% consists of heavier elements, including oxygen, carbon, neon, iron, and others.

The Sun's stellar classification, based on spectral class, is G2V, and is informally designated as a yellow dwarf, because its visible radiation is most intense in the yellow-green portion of the spectrum and although its color is white, from the surface of the Earth it may appear yellow because of atmospheric scattering of blue light. In the spectral class label, G2 indicates its surface temperature of approximately 5778 K (5505 °C), and V indicates that the Sun, like most stars, is a main sequence star, and thus generates its energy by nuclear fusion of hydrogen nuclei into helium. In its core, the Sun fuses 620 million metric tons of hydrogen each second. Once regarded by astronomers as a small and relatively insignificant star, the Sun is now thought to be brighter than about 85% of the stars in the Milky Way galaxy, most of which are red dwarfs. The absolute magnitude of the Sun is +4.83; however, as the star closest to Earth, the Sun is the brightest object in the sky with an apparent magnitude of −26.74. The Sun's hot corona continuously expands in space creating the solar wind, a stream of charged particles that extends to the heliopause at roughly 100 astronomical units. The bubble in the interstellar medium formed by the solar wind, the heliosphere, is the largest continuous structure in the Solar System.



  1. Match the phenomena with their definitions.

luminosity


the study of the interaction between radiation (electromagnetic radiation, or light, as well as particle radiation) and matter.

x-ray astronomy

the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, dust, and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space.

photometry


a family of techniques in which electromagnetic waves are superimposed in order to extract information about the waves. It is an important investigative technique in the fields of astronomy, fiber optics, engineering metrology, optical metrology, oceanography, seismology, quantum mechanics, nuclear and particle physics, plasma physics, remote sensing and biomolecular interactions.

spectroscopy

an interstellar cloud of dust, hydrogen gas, helium gas and other ionized gases.

polarimetry


the amount of electromagnetic energy a body radiates per unit of time.

galaxy

a technique of astronomy concerned with measuring the flux, or intensity of an astronomical object's electromagnetic radiation. Usually, it refers to measurement over large wavelength bands of radiation.

nebula

the measurement and interpretation of the polarization of transverse waves, most notably electromagnetic waves, such as radio or light waves. Typically it is done on electromagnetic waves that have traveled through or have been reflected, refracted, or diffracted by some material in order to characterize that object.

Interferometry

the branch of astronomy dealing with the study of astronomical objects which emit X-rays, and the methods used to detect such objects.

interstellar medium (or ISM)

a massive, luminous ball of plasma held together by gravity. At the end of its lifetime, it can also contain a proportion of degenerate matter.

star

a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas dust, and an important but poorly understood component tentatively dubbed dark matter.



  1. Render the text in English.

В отличие от физики, в основе которой лежит эксперимент, связанный с произвольным изменением условий протекания явления, астрофизика основывается главным образом на наблюдениях, когда исследователь не имеет возможности влиять на ход физического процесса. Однако при изучении того или иного явления обычно представляется возможность наблюдать его на многих небесных объектах при различных условиях, так что в конечном счёте астрофизика оказывается в не менее благоприятном положении, чем экспериментальная физика. Во многих случаях условия, в которых находится вещество в небесных телах и системах, намного отличаются от доступных современным физическим лабораториям (сверхвысокие и сверхнизкие плотности, высокие температуры и т. п.). Благодаря этому астрофизические исследования нередко приводят к открытию новых физических закономерностей.

Исторически сложилось разделение наблюдательной астрофизики на отдельные дисциплины по двум признакам: по методам наблюдения и по объектам наблюдения. Различным методам посвящены такие дисциплины, как астрофотометрия, астроспектроскопия, астроспектрофотометрия, рентгеновская астрономия, гамма-астрономия и др. Примером дисциплин, выделенных по объекту исследования, могут служить: физика Солнца, физика планет, физика туманностей галактических, физика звёзд и др.

По мере развития техники космических полётов в астрофизических исследованиях всё большую роль играет внеатмосферная астрономия, основанная на наблюдениях с помощью инструментов, размещенных на искусственных спутниках Земли и космических зондах. С развитием космонавтики появилась возможность устанавливать такие инструменты также и на других небесных телах (прежде всего на Луне). На этой же основе предполагается развитие экспериментальной астрономии. На грани наблюдательной и экспериментальной астрономии находятся радиолокационная астрономия (радиолокация метеоров, Луны, ближайших к Земле планет), а также лазерная астрономия, получающие информацию о небесных телах, используемую в астрофизике, путём их искусственного освещения пучками электромагнитных волн.


  1. Translate the text into English. What are the main techniques of optical astronomy?

Оптическая астрономия - самый старый раздел астрономии, изучающий различными физическими методами электро-магнитное излучение небесных объектов в диапазоне длин волн от 0,3 до 10 мкм (оптическое окно прозрачности земной атмосферы). При работе оптического телескопов вне атмосферы (на ИСЗ) их волновой диапазон несколько расширяется за счёт участков ИК- и УФ-диапазонов, примыкающих к оптическому диапазону.

Основная масса вещества Вселенной, излучающего в оптическом диапазоне, сосредоточена в звёздах. Электро-магнитное излучение звёзд и межзвёздного газа генерируется главным образом за счёт энергии теплового движения ионов и электронов и называется тепловым излучением. Различают несколько типов энергетических переходов частиц, порождающих тепловое излучение: 1) свободно-свободные переходы электрона в электрическое поле иона; электрон, испустивший (поглотивший) фотон, остаётся свободным; спектр излучения в этом случае непрерывный, он характерен для сильно ионизованного газа при высокой температуре; 2) свободно-связанные переходы при рекомбинации свободного электрона с ионом; они дают непрерывный спектр излучения с длиной волны короче предела спектральной серии; 3) связанно-связанные переходы электрона в атоме с одного уровня энергии на другой с испусканием или поглощением фотона, они порождают излучение или поглощение в спектральных линиях. Наличие спектральных линий в оптическом излучении небесных объектов даёт обширную информацию об их физических характеристиках: температуре, химическом составе, плотности, скорости движения вещества и др.



Излучение некоторых объектов в оптическом диапазоне носит нетепловой характер. Это, прежде всего, синхротронное излучение, характерное для квазаров, активных ядер галактик, пульсаров и туманностей, образовавшихся в результате взрыва сверхновых звёзд.

13. Translate the sentences into English.

  1. Целью астрофизических исследований является понимание строения, взаимодействия и эволюции небесных тел, их систем и Вселенной как целого.

  2. Диапазон физических параметров – плотности, температуры, давления, напряженности магнитного поля и т.п., с которыми приходится иметь дело в астрофизике, далеко превосходит то, что достижимо в земных лабораториях.
    Основным методом исследования в астрофизике служит не активный эксперимент (как в физике, химии и т.п.), а пассивное наблюдение.

  3. Обычно астрофизику подразделяют на наблюдательную и теоретическую, хотя в последние десятилетия 20 в. граница между ними стала весьма размытой.

  4. В зависимости от того, откуда проводятся наблюдения, различают наземную и внеатмосферную наблюдательную астрофизику.

  5. Подавляющая часть информации в астрофизике получается путем регистрации и анализа электромагнитного излучения небесных тел.

  6. Изучение планет, в первую очередь земной группы, а также астероидов и спутников планет стало предметом планетологии – новой дисциплины, сложившейся на стыке астрономии, геологии и геофизики.

  7. Космические исследования позволили получить крупномасштабные изображения и выполнить картирование поверхностей Луны, планет земной группы, спутников планет, ряда астероидов и ядер нескольких комет.

  8. Прояснилась относительная роль эндогенных (вулканизм, тектонические перемещения) и экзогенных факторов (метеоритная бомбардировка) и процессов эрозии в формировании рельефа поверхностей планет.

  9. Общепринятая точка зрения состоит в том, что планеты сформировались около 5 млрд. лет назад, вскоре после рождения Солнца, из окружавшего его газо-пылевого диска. Подобные диски обнаружены у некоторых звезд. Однако детали процесса формирования Солнечной системы известны плохо.

  10. Другая важнейшая перспективная задача исследований экзопланет – попытка обнаружения планет земного типа (не газовых) с атмосферами, содержащими озон и водяной пар.

  11. Многие явления, наблюдаемые на звездах, были поняты благодаря тому, что их гораздо детальнее удалось ранее исследовать на Солнце.

  12. Гелиофизические исследования имеют прикладное значение из-за прямого воздействия событий на Солнце на биосферу, в том числе на здоровье людей и на их технологическую деятельность (радиосвязь, космонавтика и др.).


14. Look through the exercises and answer the following questions:

  1. What is the main difference between physics and astrophysics?

  2. What subfields of astrophysics do you know?

  3. What are the directions of the future developments in astrophysics?

Supplementary material

Read the text and answer the questions:

  1. What other Space Telescope project do you know?

  2. Which of them are launched by NASA, ESA (European Space Agency), Roscosmos (the Russian Federal Space Agency)?

  3. Are there any space telescopes launched by the forth party?

  4. What other Space Agencies work in this direction?

  5. Can you explain the tradition of naming Space Telescopes?

Spitzer Space Telescope

spitzer space telescope prior to launch

The Spitzer Space Telescope prior to launch

The Spitzer Space Telescope (SST), formerly the Space Infrared Telescope Facility (SIRTF) is an infrared space observatory launched in 2003. It is the fourth and final of the NASA Great Observatories program.

The planned mission period was to be 2.5 years with a pre-launch expectation that the mission could extend to five or slightly more years until the onboard liquid helium supply was exhausted. This occurred on 15 May 2009. Without liquid helium to cool the telescope to the very cold temperatures needed to operate, most instruments are no longer usable. However, the two shortest wavelength modules of the IRAC camera are still operable with the same sensitivity as before the cryogen was exhausted, and will continue to be used in the Spitzer Warm Mission.

In keeping with NASA tradition, the telescope was renamed after successful demonstration of operation, on December 18, 2003. Unlike most telescopes which are named after famous deceased astronomers by a board of scientists, the name for SIRTF was obtained from a contest open to the general public.

The contest led to the telescope being named in honor of Lyman Spitzer, one of the 20th century's great scientists. Though he was not the first to propose the idea of the space telescope (Hermann Oberth being the first, in Wege zur Raumschiffahrt, 1929, and also in Die Rakete zu den Planetenräumen, 1923), Spitzer wrote a 1946 report for RAND describing the advantages of an extraterrestrial observatory and how it could be realized with available (or upcoming) technology. He has been cited for his pioneering contributions to rocketry and astronomy, as well as "his vision and leadership in articulating the advantages and benefits to be realized from the Space Telescope Program."

The US$800 million Spitzer was launched from Cape Canaveral Air Force Station, on a Delta II 7920H ELV rocket, Monday, 25 August 2003 at 13:35:39 UTC-5 (EDT).

It follows a rather unusual orbit, heliocentric instead of geocentric, trailing and drifting away from Earth's orbit at approximately 0.1 astronomical unit per year (a so-called "earth-trailing" orbit). The primary mirror is 85 centimetres (33 in) in diameter, f/12 and made of beryllium and was cooled to 5.5 K (−449.77 °F). The satellite contains three instruments that allowed it to perform imaging and photometry from 3 to 180 micrometers, spectroscopy from 5 to 40 micrometers, and spectrophotometry from 5 to 100 micrometers.

History

By the early 1970s, astronomers began to consider the possibility of placing an infrared telescope above the obscuring effects of Earth's atmosphere. In 1979, a National Research Council of the National Academy of Sciences report, A Strategy for Space Astronomy and Astrophysics for the 1980s, identified a Space Infrared Telescope Facility (SIRTF) as "one of two major astrophysics facilities [to be developed] for Spacelab", a Shuttle-borne platform. Anticipating the major results from an upcoming Explorer satellite and from the Shuttle mission, the report also favored the "study and development of ... long-duration spaceflights of infrared telescopes cooled to cryogenic temperatures." The launch in January 1983 of the Infrared Astronomical Satellite, jointly developed by the United States, the Netherlands, and the United Kingdom, to conduct the first infrared survey of the sky, whetted the appetites of scientists worldwide for follow-up space missions capitalizing on the rapid improvements in infrared detector technology.

Earlier infrared observations had been made by both space-based and ground-based observatories. Ground-based observatories have the drawback that at infrared wavelengths or frequencies, both the Earth's atmosphere and the telescope itself will radiate (glow) strongly. Additionally, the atmosphere is opaque at most infrared wavelengths. This necessitates lengthy exposure times and greatly decreases the ability to detect faint objects. It could be compared to trying to observe the stars at noon. Previous space-based satellites (such as IRAS, the Infrared Astronomical Satellite, and ISO, the Infrared Space Observatory) were operational during the 1980s and 1990s and great advances in astronomical technology have been made since then.

Most of the early concepts envisioned repeated flights aboard the NASA Space Shuttle. This approach was developed in an era when the Shuttle program was expected to support weekly flights of up to 30 days duration. A May 1983 NASA proposal described SIRTF as a Shuttle-attached mission, with an evolving scientific instrument payload. Several flights were anticipated with a probable transition into a more extended mode of operation, possibly in association with a future space platform or space station. SIRTF would be a 1-meter class, cryogenically cooled, multi-user facility consisting of a telescope and associated focal plane instruments. It would be launched on the Space Shuttle and remain attached to the Shuttle as a Spacelab payload during astronomical observations, after which it would be returned to Earth for refurbishment prior to re-flight. The first flight was expected to occur about 1990, with the succeeding flights anticipated beginning approximately one year later. However, the Spacelab-2 flight aboard STS-51-F showed that the Shuttle environment was poorly suited to an onboard infrared telescope due to contamination from the relatively "dirty" vacuum associated with the orbiters. By September 1983 NASA was considering the "possibility of a long duration [free-flyer] SIRTF mission".

Spitzer is the only one of the Great Observatories not launched by the Space Shuttle, which had been originally intended. However after the 1986 Challenger disaster, the Centaur LH2/LOX upper stage, which would have been required to place it in its final orbit, was banned from Shuttle use. The mission underwent a series of redesigns during the 1990s, primarily due to budget considerations. This resulted in a much smaller but still fully capable mission which could use the smaller Delta II expendable launch vehicle.

One of the most important advances of this redesign was an Earth-trailing orbit. Cryogenic satellites that require liquid helium (LHe, T ≈ 4 K) temperatures in near-Earth orbit are typically exposed to a large heat load from the Earth, and consequently entail large usage of LHe coolant, which then tends to dominate the total payload mass and limits mission life. Placing the satellite in solar orbit far from Earth allowed innovative passive cooling such as the sun shield, against the single remaining major heat source to drastically reduce the total mass of helium needed, resulting in an overall smaller lighter payload, with major cost savings. This orbit also simplifies telescope pointing, but does require the Deep Space Network for communications.

The primary instrument package (telescope and cryogenic chamber) was developed by Ball Aerospace & Technologies Corp., in Boulder, CO. The individual instruments were developed jointly by industrial, academic, and government institutions, the principals being Cornell, the University of Arizona, the Smithsonian Astrophysical Observatory, Ball Aerospace, and Goddard Spaceflight Center. The infrared detectors were developed by Raytheon in Goleta, California. Raytheon used indium antimonide and a doped silicon detector in the creation of the infrared detectors. It is stated that these detectors are 100 times more sensitive than what was once available in the beginning of the project during the 1980's. The spacecraft was built by Lockheed Martin. The mission is operated and managed by the Jet Propulsion Laboratory and the Spitzer Science Center, located on the Caltech campus in Pasadena, California.

Instruments

Spitzer carries three instruments on-board:

IRAC (Infrared Array Camera), an infrared camera which operates simultaneously on four wavelengths (3.6 µm, 4.5 µm, 5.8 µm and 8 µm). Each module uses a 256 × 256 pixel detector—the short wavelength pair use indium antimonide technology, the long wavelength pair use arsenic-doped silicon impurity band conduction technology. The two shorter wavelength bands (3.6 µm & 4.5 µm) for this instrument remain productive after LHe depletion in the spring of 2009, at the telescope equilibrium temperature of around 30 K, so IRAC continues to operate as the "Spitzer Warm Mission".

IRS (Infrared Spectrograph), an infrared spectrometer with four sub-modules which operate at the wavelengths 5.3-14 µm (low resolution), 10-19.5 µm (high resolution), 14-40 µm (low resolution), and 19-37 µm (high resolution). Each module uses a 128x128 pixel detector—the short wavelength pair use arsenic-doped silicon blocked impurity band technology, the long wavelength pair use antimony-doped silicon blocked impurity band technology.

MIPS (Multiband Imaging Photometer for Spitzer), three detector arrays in the far infrared (128 × 128 pixels at 24 µm, 32 × 32 pixels at 70 µm, 2 × 20 pixels at 160 µm). The 24 µm detector is identical to one of the IRS short wavelength modules. The 70 µm detector uses gallium-doped germanium technology, and the 160 µm detector also uses gallium-doped germanium, but with mechanical stress added to each pixel to lower the bandgap and extend sensitivity to this long wavelength.[

As an example of data from the different instruments, the nebula Henize 206 was imaged in 2004, allowing comparison of images from each device.



Results

http://upload.wikimedia.org/wikipedia/commons/thumb/2/2a/169141main_piaa09178.jpg/300px-169141main_piaa09178.jpg

The Helix Nebula. Blue shows infrared light of 3.6 to 4.5 micrometers; green shows infrared light of 5.8 to 8 micrometers; and red shows infrared light of 24 micrometers.



http://upload.wikimedia.org/wikipedia/commons/thumb/a/a5/andromeda_galaxy_ssc2005-20a1.jpg/300px-andromeda_galaxy_ssc2005-20a1.jpg

The Andromeda Galaxy (M31) taken by Spitzer in infrared, MIPS, 24 micrometers 2004 August 25.

The first images taken by SST were designed to show off the abilities of the telescope and showed a glowing stellar nursery; a big swirling, dusty galaxy; a disc of planet-forming debris; and organic material in the distant universe. Since then, many monthly press releases have highlighted Spitzer's capabilities, as the NASA and ESA images do for the Hubble Space Telescope.

As one of its most noteworthy observations, in 2005, SST became the first telescope to directly capture the light from extrasolar planets, namely the "hot Jupiters" HD 209458b and TrES-1. (It did not resolve that light into actual images though.)[22] This was the first time extrasolar planets had actually been visually seen; earlier observations had been indirectly made by drawing conclusions from behaviors of the stars the planets were orbiting. The telescope also discovered in April 2005 that Cohen-kuhi Tau/4 had a planetary disk that was vastly younger and contained less mass than previously theorized, leading to new understandings of how planets are formed.

While some time on the telescope is reserved for participating institutions and crucial projects, astronomers around the world also have the opportunity to submit proposals for observing time. Important targets include forming stars (young stellar objects, or YSOs), planets, and other galaxies. Images are freely available for educational and journalistic purposes.

In 2004, it was reported that Spitzer had spotted a faintly glowing body that may be the youngest star ever seen. The telescope was trained on a core of gas and dust known as L1014 which had previously appeared completely dark to ground-based observatories and to ISO (Infrared Space Observatory), a predecessor to Spitzer. The advanced technology of Spitzer revealed a bright red hot spot in the middle of L1014.

Scientists from the University of Texas at Austin, who discovered the object, believe the hot spot to be an example of early star development, with the young star collecting gas and dust from the cloud around it. Early speculation about the hot spot was that it might have been the faint light of another core that lies 10 times further from Earth but along the same line of sight as L1014. Follow-up observation from ground-based near-infrared observatories detected a faint fan-shaped glow in the same location as the object found by Spitzer. That glow is too feeble to have come from the more distant core, leading to the conclusion that the object is located within L1014. (Young et al., 2004)

In 2005, astronomers from the University of Wisconsin at Madison and Whitewater determined, on the basis of 400 hours of observation on the Spitzer Space Telescope, that the Milky Way Galaxy has a more substantial bar structure across its core than previously recognized.

Also in 2005, astronomers Alexander Kashlinsky and John Mather of NASA's Goddard Space Flight Center reported that one of Spitzer's earliest images may have captured the light of the first stars in the universe. An image of a quasar in the Draco constellation, intended only to help calibrate the telescope, was found to contain an infrared glow after the light of known objects was removed. Kashlinsky and Mather are convinced that the numerous blobs in this glow are the light of stars that formed as early as 100 million years after the big bang, red shifted by cosmic expansion.

In March 2006, astronomers reported an 80-light-year-long nebula near the center of the Milky Way Galaxy, the Double Helix Nebula, which is, as the name implies, twisted into a double spiral shape. This is thought to be evidence of massive magnetic fields generated by the gas disc orbiting the supermassive black hole at the galaxy's center, 300 light years from the nebula and 25,000 light years from Earth. This nebula was discovered by the Spitzer Space Telescope, and published in the magazine Nature on March 16, 2006.

In May 2007, astronomers successfully mapped the atmospheric temperature of HD 189733 b, thus obtaining the first map of some kind of an extrasolar planet.

Since September 2006 the telescope participates in a series of surveys called the Gould Belt Survey, observing the Gould's Belt region in multiple wavelengths. The first set of observations by the Spitzer Space Telescope were completed from September 21, 2006 through September 27. Resulting from these observations, the team of astronomers led by Dr. Robert Gutermuth, of the Harvard-Smithsonian Center for Astrophysics reported the discovery of Serpens South, a cluster of 50 young stars in the Serpens constellation.

In August 2009, the telescope found evidence of a high-speed collision between two burgeoning planets orbiting a young star.

In October 2009, astronomers Anne J. Verbiscer, Michael F. Skrutskie, and Douglas P. Hamilton published findings of the "Phoebe ring" of Saturn, which was found with the telescope; the ring is a huge, tenuous disc of material extending from 128 to 207 times the radius of Saturn.



GLIMPSE and MIPSGAL surveys

GLIMPSE, the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire, is a survey spanning 300° of the inner Milky Way galaxy. It consists of approximately 444,000 images taken at 4 separate wavelengths using the Infrared Array Camera.

MIPSGAL is a similar survey covering 278° of the galactic disk at longer wavelengths.

On June 3, 2008, scientists unveiled the largest, most detailed infra-red portrait of the Milky Way, created by stitching together more than 800,000 snapshots, at the 212th meeting of the American Astronomical Society in St.Louis, Missouri.



Использованная литература:

  1. Астрофизика, Большая Советская Энциклопедия.

  2. Иванов В.В., Астрофизика. Большая Российская Энциклопедия (БРЭ), 2004г.

  3. Научно-технический энциклопедический словарь. http://dic.academic.ru/contents.nsf/ntes/

  4. Новиков С. Б., "Физика Космоса", 1986

  5. The Science Dictionary – Houghton Mifflin Company, 2005.

  6. http://helios.gsfc.nasa.gov/gloss_ab.html

  7. http://en.wikipedia.org/wiki/Main_Page

  8. http://www.spitzer.caltech.edu/