AstronomijaAstronomijakratka povijest problematikekratka povijest problematike

Područje interesaPodručje interesa

PlanetPlanetii SSunčev sustavunčev sustav ZvijezdeZvijezde Međuzvjezdani prostorMeđuzvjezdani prostor GalGalaksijeaksije Aktivne galaktičke jezgre (Aktivne galaktičke jezgre (AGNAGN)) Kvazari (eng. quasar - quasi-stellar radio source) Kvazari (eng. quasar - quasi-stellar radio source) Klasteri galaksijaKlasteri galaksija Pulsari (brzorotirajuće neutronske zvijezde)Pulsari (brzorotirajuće neutronske zvijezde) SvemirSvemir

Sunčev sustavSunčev sustav

Fizika Fizika SSuncaunca SolaSolarni vjetarrni vjetar PlanetPlaneti i Njihovi satelitiNjihovi sateliti AsteroidAsteroidii NEOsNEOs (eng. Near (eng. Near

eart objects)eart objects) PojasiPojasi InterplanetInterplanetarna arna

prašinaprašina

ZvijezdeZvijezde

promjenjive zvijezdepromjenjive zvijezde dvojne zvijezdedvojne zvijezde patuljci, divovipatuljci, divovi SupernoveSupernove kompaktni objektikompaktni objekti

((crne rupecrne rupe, , bijeli bijeli patuljcipatuljci, neutro, neutronskenske zvijezdezvijezde))

Međuzvjezdani prostorMeđuzvjezdani prostor

Nastanak zvijezdaNastanak zvijezdaAstro-kemijaAstro-kemijaStruktura i razvoj Struktura i razvoj

zvijezdazvijezdaNuklearna Nuklearna

astrofizikaastrofizika

GalaksijeGalaksije

Nastanak i Nastanak i formiranjeformiranje

StruStrukturakturaNaseljenostNaseljenostDDinamikainamika

AGN (Aktivne galaktičke jezgre) AGN (Aktivne galaktičke jezgre) KvazariKvazari

nastanaknastanakklasifikacijaklasifikacijagorivogorivoevolucijaevolucijagustoćagustoća

KlasteriKlasteri

Nastanak i Nastanak i razvojrazvoj

StruStrukturakturaTamna tvarTamna tvarGravitacijske Gravitacijske

lećeleće

SvemirSvemir

Starost i veličinaStarost i veličinaNastanak i razvojNastanak i razvojTamna materija , Tamna materija ,

stringovi, egzotične stringovi, egzotične česticečestice

TopoloTopologijagija ( (oblikoblik))

Znanstveni elementi u astronomijiZnanstveni elementi u astronomiji PromatranjePromatranje

• Zemaljsko Zemaljsko (opti(optičkočko, , infrainfracrvenocrveno, radio), radio)

• VanplanetarnoVanplanetarno ((sateliti i satelitske sateliti i satelitske platformeplatforme; UV, x-ray); UV, x-ray)

RačunanjeRačunanje• AnalAnaliza podatakaiza podataka• KKompleompleksniksni problem problemii• NumeriNumeričke čke simula simulacijecije

AnalAnalizaiza• objeobjektivnostktivnost• asimilasimiliranjeiranje formi i formi i

podatakapodataka• linearlinearnono & & nenelinearlinearnono

razmišljanjerazmišljanje

PisanjePisanje• publikacijapublikacija• prprijedlogaijedloga• preprezentacijazentacija

ZapošljavanjeZapošljavanje (danas) (danas)

Što astronomi Što astronomi nene rade rade

Pišu horoskopePišu horoskope Imaju vezu s vanzemaljskim Imaju vezu s vanzemaljskim

civilizacijamacivilizacijama Memoriraju konstelacijeMemoriraju konstelacije Cijelo vrijeme gledaju kroz teleskopCijelo vrijeme gledaju kroz teleskop

RadioastronomijaRadioastronomija

Kozmičko zračenje 3KKozmičko zračenje 3K

Elektromagnetski valoviElektromagnetski valovi

E=hE=h c= c=

Duži valoviNiža energijaNiža frekvencija

Kraćo valoviVeća energijaViša frekvencija

Elektromagnetski Elektromagnetski spektarspektar

Elektromagnetski prozor kroz Elektromagnetski prozor kroz atmosferu!atmosferu!

Izvori elektromagnetskog zračenjaIzvori elektromagnetskog zračenja

TermalniTermalni• Zračenje crnog Zračenje crnog

tijelatijela• Kontinuirana Kontinuirana

emisija ioniziranog emisija ioniziranog plina (plazma)plina (plazma)

• Emisija spektralnog Emisija spektralnog zračenja atoma i zračenja atoma i molekulamolekula

NetermalniNetermalni• Sinkrotronsko Sinkrotronsko

zračenjezračenje• MASERSMASERS

Plankov zakonPlankov zakonu(ν,T) = 4I(ν,T) / c

Zračenje crnog tijela - SjajZračenje crnog tijela - Sjaj

Sjaj elektromagnetskog zračenja različitih valnih dužina za Sjaj elektromagnetskog zračenja različitih valnih dužina za crno tijelo na različitim temperaturamacrno tijelo na različitim temperaturama

MASERMASER

Sinkrotronsko zračenjeSinkrotronsko zračenje

PolarizaPolarizacojska svojstvacojska svojstva EM zračenja daju EM zračenja daju informacije o geometriji magnetskog poljainformacije o geometriji magnetskog polja

Sinkrotronsko zračenjeSinkrotronsko zračenje

Zakon obrnutog kvadrata !Zakon obrnutog kvadrata !

ZabludaZabluda

Radio program koji se ne sluša!

Radio Radio TeleskopiTeleskopi

Dvije izvedbeDvije izvedbe::

Polje radio antena

Green Bank Telescope, WV Very Large Array, NM

Radio antena

1980 1980 godinegodine Dvadest sedamDvadest sedam

25-m25-metarskih etarskih rekonfigurabilnihrekonfigurabilnihantenantena;a; Socorro, Socorro, NM NM

Više publikacija Više publikacija od bilo kojeg od bilo kojeg teleskopa na teleskopa na svijetusvijetu

The Very Large ArrayThe Very Large Array (VLA) (VLA)

Very Long Baseline ArrayVery Long Baseline Array (VLBA) (VLBA)

1993 1993 godinegodine OOperirane ozperirane oz

SocorroSocorro-a-a DesetDeset 25-m 25-m

antennas antennas diljemdiljem SADSAD, , KKanadanadee, P.R., P.R.

Najviša Najviša rezolucijarezolucija

PočeciPočecieksperiment Janskogeksperiment Janskog

Promatra nemodulirani doprinos RF (static)

Postepeno s mijenja intenzitet s periodom od gotovo 24hSunce izvor?maksimum 4 minute rani svaki danIzvor izvan Sunčeva sustavaIzvor u Mlječnoj stazi!1933 objavljuje rezultate

Karl G. Jansky (1905-1950)

Reberov tip radioteleskopaReberov tip radioteleskopaDespite the implications of Jansky’s work, both on the design of radio receivers, as well as for radio astronomy, no one paid much attention at first. Then, in 1937, Grote Reber, another radio engineer, picked up on Jansky’s discoveries and built the prototype for the modern radio telescope in his back yard in Wheaton, Illinois.

He started out looking for radiation at shorter wavelengths, thinking these wavelengths would be stronger and easier to detect. He didn’t have much luck, however, and ended up modifying his antenna to detect radiation at a wavelength of 1.87 meters (about the height of a human), where he found strong emissions along the plane of the Milky Way.

Reconfigurable Arrays: Zoom Lens Effect Reconfigurable Arrays: Zoom Lens Effect

Više Više detektora – detektora – bolja bolja rezolucijarezolucija

VLAVLBA

Radio Telescopes: SensitivityRadio Telescopes: Sensitivity

• VLA B-array: Total VLA B-array: Total telescope telescope collecting area is collecting area is only 0.02% of land only 0.02% of land areaarea

More spread-out More spread-out arrays can only arrays can only image very image very bright, compact bright, compact sourcessources

• Sensitivity (how faint of a thing you can “see”) depends on how much of the area of the telescope/array is actually collecting data

Green Bank Telescope, WV

Parabolic DishParabolic Dish

Aluminum Aluminum reflecting reflecting surface surface

Focuses Focuses incoming waves incoming waves to prime focus to prime focus or sub-reflectoror sub-reflector

Sub-reflector

Sub-reflectorSub-reflector

Feed Pedestal

Sub-reflector

• Re-directs incoming waves to Feed Pedestal

• Can be rotated to redirect radiation to a number of different receivers

1.5GHz 20cm 2.3GHz 13cm 4.8GHz 6cm 8.4GHz 4cm 14GHz 2cm 23GHz 1.3cm 43GHz 7mm 86GHz 3mm

327MHz 90cm610MHz 50cm

Feed PedestalFeed Pedestal

Antenna Feed and Antenna Feed and ReceiversReceivers

Benefits of Observing in the Benefits of Observing in the RadioRadio

Track physical processes with no Track physical processes with no signature at other wavelengthssignature at other wavelengths

Radio waves can travel through dusty Radio waves can travel through dusty regions regions

Can provide information on magnetic Can provide information on magnetic field strength and orientationfield strength and orientation

Can provide information on line-of-sight Can provide information on line-of-sight velocitiesvelocities

Daytime observing (for cm-scale Daytime observing (for cm-scale wavelengths anyway)wavelengths anyway)

Primary Astrophysical Processes Primary Astrophysical Processes Emitting Radio RadiationEmitting Radio Radiation

Synchrotron RadiationSynchrotron Radiation• Charged particles moving along magnetic field Charged particles moving along magnetic field

lineslines Thermal emission Thermal emission

• Cool bodiesCool bodies• Charged particles in a plasma moving aroundCharged particles in a plasma moving around

Spectral Line emissionSpectral Line emission• Discrete transitions in atoms and molecules Discrete transitions in atoms and molecules

When charged particles change direction, they emit radiation

Thermal EmissionThermal Emission

Emission from warm Emission from warm bodiesbodies• ““Blackbody” Blackbody”

radiation radiation • Bodies with Bodies with

temperatures of ~ 3-temperatures of ~ 3-30 K emit in the mm 30 K emit in the mm & submm bands& submm bands

Emission from Emission from accelerating accelerating charged particlescharged particles• ““Bremsstrahlung” or Bremsstrahlung” or

free-free emission free-free emission from ionized plasmasfrom ionized plasmas

Nobelova nagrada za otkriće Nobelova nagrada za otkriće kozmičkog mikrovalnog kozmičkog mikrovalnog pozadinskog zračenjapozadinskog zračenja

Arno Allan Penzias Robert Woodrow Wilson

The Nobel Prize in Physics 1993The Nobel Prize in Physics 1993

for the discovery of a new type of for the discovery of a new type of pulsar, a discovery that has opened pulsar, a discovery that has opened up new possibilities for the study of up new possibilities for the study of gravitation" gravitation"

Russell A. Hulse Joseph H. Taylor Jr

Emits photon with a wavelength of 21 cm (frequency of 1.42 GHz)

Spectral Line emission: hyperfine Spectral Line emission: hyperfine transition of neutral Hydrogentransition of neutral Hydrogen

Transition probability=3x10-15 s-1 = once in 11 Myr

Spectral Line emission: Spectral Line emission: molecular rotational and molecular rotational and

vibrational modesvibrational modes Commonly observed Commonly observed

molecules in space:molecules in space:• Carbon Monoxide (CO)Carbon Monoxide (CO)

• Water (HWater (H22O), OH, HCN, O), OH, HCN, HCOHCO++, CS, CS

• Ammonia (NHAmmonia (NH33), ), Formaldehyde (HFormaldehyde (H22CO)CO)

Less common Less common molecules:molecules:• Sugar, Alcohol, Antifreeze Sugar, Alcohol, Antifreeze

(Ethylene Glycol), …(Ethylene Glycol), …

malondialdyde

Spectral Line Doppler effectSpectral Line Doppler effect

Spectral lines have fixed Spectral lines have fixed and very well determined and very well determined frequenciesfrequencies

The frequency of a source The frequency of a source will changed when it moves will changed when it moves towards or away from youtowards or away from you

• Comparing observed frequency to known frequency tells you the velocity of the source towards or away from you

Sees original wavelength

Sees shorter wavelength

Sees longer wavelength

Special example of Spectral Special example of Spectral Line observation:Line observation:Doppler Radar ImagingDoppler Radar Imaging

Transmit radio wave with well defined frequency…

..observe same frequency

…bounce off

object…

NASA’s Goldstone Solar System Radar Very Large Array

Brief Tour of the Radio UniverseBrief Tour of the Radio Universe

Solar SystemSolar System• Sun, Planets, AsteroidsSun, Planets, Asteroids

Galactic objectsGalactic objects• Dark clouds, proto-stellar disks, supernova Dark clouds, proto-stellar disks, supernova

remnants, remnants, GalaxiesGalaxies

• Magnetic fields, neutral hydrogenMagnetic fields, neutral hydrogen Radio Jets Radio Jets The UniverseThe Universe

K-band 23 GHz

Ka-band 33 GHzQ-band 41 GHzV-band 61 GHzW-band 94 GHz

Shepherding in the era of “Precision Cosmology”

Background=3 K blackbody radiation

Wilkinson Microwave Anisotropy Probe Wilkinson Microwave Anisotropy Probe (WMAP)(WMAP) map.gsfc.nasa.gov

image of the cosmic microwave background radiation anisotropy. It has the most precise image of the cosmic microwave background radiation anisotropy. It has the most precise thermal emission spectrum known and corresponds to a temperature of 2.725 kelvin (K) thermal emission spectrum known and corresponds to a temperature of 2.725 kelvin (K)

with an emission peak at 160.2 GHz with an emission peak at 160.2 GHz

Radio pregled Mlječne stazeRadio pregled Mlječne staze

(a) radio (b) infrared, (c) visible(d) X-rayEach illustration shows the Milky Way stretching horizontally across the picture.

PulsarPulsar PulsarsPulsars are highly magnetized, rotating are highly magnetized, rotating

neutron neutron starsstars that emit a beam of that emit a beam of electromagneticelectromagnetic radiationradiation. The observed . The observed periods of their pulses range from 1.4 periods of their pulses range from 1.4 millisecondsmilliseconds to 8.5 seconds. The radiation to 8.5 seconds. The radiation can only be observed when the beam of can only be observed when the beam of emission is pointing towards the emission is pointing towards the EarthEarth. .

This is called the lighthouse effect and gives This is called the lighthouse effect and gives rise to the pulsed nature that gives pulsars rise to the pulsed nature that gives pulsars their name. Because neutron stars are very their name. Because neutron stars are very dense objects, the rotation period and thus dense objects, the rotation period and thus the interval between observed pulses are the interval between observed pulses are very regular. For some pulsars, the regularity very regular. For some pulsars, the regularity of pulsation is as precise as an of pulsation is as precise as an atomicatomic clockclock..

Pulsars are known to have planets orbiting Pulsars are known to have planets orbiting them, as in the case of them, as in the case of PSR B1257+12PSR B1257+12. . Werner Becker of the Werner Becker of the MaxMax--PlanckPlanck-Institut -Institut fürfür extraterrestrischeextraterrestrische PhysikPhysik said in 2006, "The said in 2006, "The theory of how pulsars emit their radiation is theory of how pulsars emit their radiation is still in its infancy, even after nearly forty still in its infancy, even after nearly forty years of work.years of work.

KvazarKvazar A A Quasi-stellar radio sourceQuasi-stellar radio source ( (QuasarQuasar) is a powerfully ) is a powerfully

energetic and distant energetic and distant galaxygalaxy with an with an activeactive galacticgalactic nucleusnucleus. Quasars were first identified as being high . Quasars were first identified as being high redshiftredshift sources sources of of electromagneticelectromagnetic energyenergy, including , including radio radio waveswaves and and visiblevisible lightlight, that were point-like, similar to , that were point-like, similar to starsstars, rather , rather than extended sources similar to than extended sources similar to galaxiesgalaxies..

While there was initially some controversy over the nature While there was initially some controversy over the nature of these objects — as recently as the 1980s, there was no of these objects — as recently as the 1980s, there was no clear consensus as to their nature — there is now a clear consensus as to their nature — there is now a scientificscientific consensusconsensus that a quasar is a compact region 10- that a quasar is a compact region 10-10,000 10,000 SchwarzschildSchwarzschild radiiradii across surrounding the central across surrounding the central supermassivesupermassive blackblack hole hole of a galaxy, powered by its of a galaxy, powered by its accretionaccretion discdisc..

MaserMaser [[editedit] Historical background] Historical background In 1965 an unexpected discovery was made by Weaver In 1965 an unexpected discovery was made by Weaver et al.et al.[3][3] - emission lines in - emission lines in

space of unknown origin at a frequency of 1665 MHz. At this time many people still space of unknown origin at a frequency of 1665 MHz. At this time many people still thought that molecules could not exist in space, so the emission was at first put down thought that molecules could not exist in space, so the emission was at first put down to an interstellar species named to an interstellar species named MysteriumMysterium, but the emission was soon identified as , but the emission was soon identified as line emission from OH molecules in compact sources within molecular cloudsline emission from OH molecules in compact sources within molecular clouds[4][4]. . More discoveries followed, with H2O emission in 1969More discoveries followed, with H2O emission in 1969[5][5], CH3OH emission in 1970, CH3OH emission in 1970[6][6] and SiO emission in 1974and SiO emission in 1974[7][7], all coming from within molecular clouds. These were , all coming from within molecular clouds. These were termed "masers", as from their narrow line-widths and high effective temperatures it termed "masers", as from their narrow line-widths and high effective temperatures it became clear that these sources were amplifying microwave radiation.became clear that these sources were amplifying microwave radiation.

Masers were then discovered around highly evolved Masers were then discovered around highly evolved Late type starsLate type stars; First was OH ; First was OH emission in 1968[8], then H2O emission in 1969[9] and SiO emission in 1974[10]. emission in 1968[8], then H2O emission in 1969[9] and SiO emission in 1974[10]. Masers were also discovered in external galaxies in 1973[11], and in our own solar Masers were also discovered in external galaxies in 1973[11], and in our own solar system in comet halos.system in comet halos.

Another unexpected discovery was made in 1982 with the discovery of emission from Another unexpected discovery was made in 1982 with the discovery of emission from an extra-galactic source with an unrivalled luminosity about 106 times larger than an extra-galactic source with an unrivalled luminosity about 106 times larger than any previous source[12]. This was termed a any previous source[12]. This was termed a megamasermegamaser because of its great because of its great luminosity, and many more megamasers have since been discovered.luminosity, and many more megamasers have since been discovered.

Evidence for an Evidence for an anti-pumpedanti-pumped (dasar) sub-thermal population in the 4830 MHz (dasar) sub-thermal population in the 4830 MHz transition of formaldehyde (H2CO) was observed in 1969 by Palmer transition of formaldehyde (H2CO) was observed in 1969 by Palmer et al.et al.