Astronomický proseminář II Galaxie a galaxie hvězdné soustavy §dvojhvězdy, vícenásobné hvězdné soustavy §hvězdokupy §galaxie §skupiny galaxií §kupy galaxií §nadkupy galaxií §vyšší struktury Galaxie a galaxie 2 vícenásobné hvězdné soustavy •dvojhvězdy – např. Sirius, Prokyon, Mira •trojhvězdy – Polárka •čtyřhvězdy – Mizar, epsilon Lyr •pětihvězdy – 91 Aql, delta Ori •šestihvězdy – Castor, Alcor (s Mizarem) •sedmihvězdy – AR Cas • •katalog Tokovinin http://www.ctio.noao.edu/~atokovin/stars/intro.html • uspořádání soustav http://kontakty.slu.cz/pict/zavinac.gif Hvězdné asociace •původ: •rozpad hvězdokup •nově vznikající hvězdokupy – hvězdy mají podobné trajektorie v prostoru •pohybové asociace –skupina UMa – od UMa, Cep až TrA –Hyády –Jesličky •hvězdné asociace –O asociace (v Ori) –OB asociace (v Sco – Cen) –R asociace (střední M, zbytky původní látky – Mon R2) –T asociace (hvězdy T Tauri) • • • OB asociace Ara OB1 • Otevřené hvězdokupy •nepravidelný tvar •stovky hvězd •výskyt u galaktické roviny •obsahují také mezihvězdný prach a plyn •jedná se o relativně mladé hvězdy, jejich seskupení je gravitačně nestabilní •Plejády, Hyády, Jesličky atd. •určení stáří podle umístění charakter. zahnutí na HRD, který je sestaven pro hvězdy konkrétní hvězdokupy • Kulové hvězdokupy • •silná koncentrace hvězd směrem ke středu, •počet hvězd řádově 106 •staré útvary (~1010 let) •gravitačně stabilní •jsou v tzv. galaktickém halu •M 13, 47 Tuc M 13 47 Tuc Figure 25.24 Globular Cluster M54. A nearly perfectly spherical cluster of stars, so dense that the central core appears as a bright patch of light rather than individual stars. •Globular Cluster M54. This beautiful Hubble Space Telescope image shows the globular cluster that is now believed to be the nucleus of the Sagittarius Dwarf Galaxy. (credit: ESA/Hubble & NASA) • základní údaje o hvězdokupách • Asociace Otevřené h. Kulové h. • •tvar nepravidelný nepravidelný kulový • •množství málo hvězd málo hvězd mnoho hvězd • •koncentrace jen u některých slabá k. silná k. • •místo výskytu spirální galaktická galaktické • v Galaxii ramena rovina halo • •poloha v HR jako u mladých jako u hvězd jako u hvězd • diagramu hvězd populace I populace II • srovnání vzhledu jesličky m3 naše Galaxie § Galaxie a galaxie 16 Galaxie •naše Galaxie, resp. její spirální ramena jsou dobře viditelná jako tzv. Mléčná dráha. Také všechny ostatní hvězdy, které jsou viditelné pouhým okem, patří do tohoto systému •Galaxii tvoří několik set miliard hvězd, velké množství mezihvězdné látky a patrně i tzv. skryté hmoty •v centru Galaxie je velmi hmotná černá díra •při pohledu z mimogalaktického prostoru by měla Galaxie plochý tvar (jako dva talíře přiklopené na sebe), pohled „shora“ by ukázal spirálovitou strukturu s centrální příčkou •rotace Galaxie je poměrně složitá •Slunce ve 2/3 vzdálenosti poloměru Galaxie od jejího středu 1 oběh za ~ 220 mil. let milkyway_lund Galaxie •Jak jsme k těmto poznatkům dospěli? • •1. model z pozorování – W. Herschel, 18. století –chyby: totožný zářivý výkon všech hvězd, konstantní prostorová hustota, neznalost mezihvězdné extinkce –výsledkem byl model Galaxie o průměru 3 kpc, Slunce uprostřed •1922 další model – Kapteyn –zářivé výkony různé, ale bez extinkce –elipsoid 8500 x 1700 pc, Slunce 650 pc od středu •1920 – Velká debata – Shapley x Curtis •role mezihvězdné látky odhalena až později –plyn tvoří až 80 % –prach – Si, grafitová, kovová a ledová zrnka Figure 25.3 Herschel’s Diagram of the Milky Way. The Sun is to the right of center in this elongated and irregularly shaped illustration of our galaxy. •Herschel’s Diagram of the Milky Way. Herschel constructed this cross section of the Galaxy by counting stars in various directions. Figure 25.4 Panel (a), at left: Photograph of Harlow Shapley. Panel (b), at right: Shapley’s diagram of the Milky Way. The Sun is labeled left of center, within parallel dashed lines representing the disk of the galaxy. White dots represent the location of globular clusters, which are not centered on the Sun but at a point near the center of the diagram. •Harlow Shapley and His Diagram of the Milky Way. (a)Shapley poses for a formal portrait. (b)His diagram shows the location of globular clusters, with the position of the Sun also marked. The black area shows Herschel’s old diagram, centered on the Sun, approximately to scale. Galaxie •Galaktická souřadnicová soustava • •základní rovina – rovina největší koncentrace hvězd • –úhel mezi rovinou galaktického rovníku a rovinou světového rovníku je 62 st. 36 min. –základní směr (ke středu G) je definován rezolucí IAU (1959): rekt. 17h 42min 29,3vt a deklinace -28st 59min 18vt –galaktická délka l a šířka b • • Galaxie •Struktura • •složení – hvězdy, mezihvězdná látka, skrytá hmota • –kulová složka (halo) –disková složka –plochá složka –jádro Galaxie • Figure 25.5 A schematic representation of the Milky Way Galaxy. On the left is the face-on view of the spiral disk, with the central bar in the center, the Cygnus spiral arm on the lower left, the Perseus arm labeled on the bottom, the smaller Orion spur labeled above that, and the Carina arm labeled on the right. On the right of the schematic is the edge-on view of the spiral disk, surrounded by serval globular clusters. The nuclear bulge is labeled in the center of both views, and the Sun is labeled on the Orion spur. The distance between the Sun and the nuclear bulge is labeled 26,000 light years. •Schematic Representation of the Galaxy. The left image shows the face-on view of the spiral disk; the right image shows the view looking edge-on along the disk. The major spiral arms are labeled. The Sun is located on the inside edge of the short Orion spur. Figure 25.10 Map of the The Milky Way Galaxy. Over-plotted on this data-based illustration of the Milky Way is a coordinate system centered on the Sun, which is located about half way from the center and the bottom of the image. It is a polar coordinate system, with zero degrees straight up from the Sun, 90O to the left, 180O straight down and 270O to the right. Distances are shown as circles of increasing radius centered on the Sun. Distances from 15,000 ly to 75,000 ly are indicated in increments of 5,000 ly. Moving outward from the Sun along the zero degree line are the “Near 3kpc Arm”, “Far 3 kpc Arm” and the “Sagittarius Arm”. Moving outward from the Sun along the 330O line (to the right of zero) are the “Norma Arm” and the “Scutum-Centaurus Arm”. Moving outward from the Sun along the 90O line are are the: “Orion Spur”, “Perseus Arm” and the “Outer Arm”. •Milky Way Bar and Arms. Here, we see the Milky Way Galaxy as it would look from above. This image, assembled from data from NASA’s WISE mission, shows that the Milky Way Galaxy has a modest bar in its central regions. Two spiral arms, Scutum-Centaurus and Perseus, emerge from the ends of the bar and wrap around the bulge. The Sagittarius and Outer arms have fewer stars than the other two arms. (credit: modification of work by NASA/JPL-Caltech/R. Hurt (SSC/Caltech)) Figure 25.11 The Sun and the Orion Spur. Portions of three spiral arms of the Milky Way are shown in this illustration. The “Cygnus arm” at top, the “Perseus arm” at center and the “Sagittarius arm” at bottom. The “Orion spur” is a stream of stars and gas runs from the Cygnus arm diagonally downward to the right through the Perseus arm and on to the Sagittarius arm. The Sun is located in the portion of the spur between the Perseus and Sagittarius arms. Objects of interest are indicated with arrows from above and below the figure. At top, from left to right are: “Sn2 289”, “Perseus transit”, “Rosetta nebula” and the “Orion nebula”. At bottom, from left to right are: “Turner S”, “Vela molecular ridge”, “Gum nebula”, “Sun”, “Cygnus X-1” and “W51”. •Orion Spur. The Sun is located in the Orion Spur, which is a minor spiral arm located between two other arms. In this diagram, the white lines point to some other noteworthy objects that share this feature of the Milky Way Galaxy with the Sun. (credit: modification of work by NASA/JPL-Caltech) Galaxie •Spirální ramena • • Figure 25.12 Simplified Model for the Formation of Spiral Arms. At left, the illustration begins with two irregular blue blobs, one above the other, with a short curved arrow at top pointing to the right indicating the direction of rotation. The next frame, with a longer curved arrow, shows how parts of the initial blobs have moved toward each other, but the parts further away have moved less, giving the appearance of two small comets. In the next frame, the curved arrow covers about 180O, and the blobs are now even more curved and elongated. In the final frame at right, the curved arrow covers 270O, and the classic spiral shape has emerged. •Simplified Model for the Formation of Spiral Arms. This sketch shows how spiral arms might form from irregular clouds of interstellar material stretched out by the different rotation rates throughout the Galaxy. The regions farthest from the galactic center take longer to complete their orbits and thus lag behind the inner regions. If this were the only mechanism for creating spiral arms, then over time the spiral arms would completely wind up and disappear. Since many galaxies have spiral arms, they must be long-lived, and there must be other processes at work to maintain them. Figure 25.13 In this plot the vertical axis is labeled “Orbital Velocity (km/s)”, and ranges from zero at bottom to 300 at top, in increments of 100 km/s. The horizontal axis is labeled “Distance from Center of Galaxy (kpc)”, and ranges from zero at left to 35 at right, in increments of 5 kpc. The rotation curve is drawn in red and starts at the origin at lower left, and rises quickly to about 250 km/s at about 2 kpc. The curve drops to about 200 km/s at 5 kpc, then rises again to near 250 km/s at about 7.5 kpc. From there is drops slightly again to near 200 km/s at 10 kpc, then begins a slow, steady rise to almost 300 km/s at 35 kpc. The blue curve shows what the rotation curve would look like if all of the matter in the Galaxy were located inside a radius of 10 kpc. The blue curve begins to drop from about 250 km/s at 15 kpc down to 100 km/s at 35 kpc. •Rotation Curve of the Galaxy. The orbital speed of carbon monoxide (CO) and hydrogen (H) gas at different distances from the center of the Milky Way Galaxy is shown in red. The blue curve shows what the rotation curve would look like if all the matter in the Galaxy were located inside a radius of 30,000 light-years. Instead of going down, the speed of gas clouds farther out remains high, indicating a great deal of mass beyond the Sun’s orbit. The horizontal axis shows the distance from the galactic center in kiloparsecs (where a kiloparsec equals 3,260 light-years). Figure 25.16 Central 10 Light-Years of the Galaxy. The bright region at lower right is Sagittarius A* and the straight filaments running from lower left to upper right are collectively known as “The Arc”. See [Figure 25_04_RImage] to see these features in context with other objects near the galactic center. •Sagittarius A. This image, taken with the Very Large Array of radio telescopes, shows the radio emission from hot, ionized gas in the center of the Milky Way. The lines slanting across the top of the image are gas streamers. Sagittarius A* is the bright spot in the lower right. (credit: modification of work by Farhad Zadeh et al. (Northwestern), VLA, NRAO) Figure 25.17 Near-infrared View of the Galactic Center. The measured orbits of eight stars are plotted orbiting the galactic center, shown as ellipses of different colors. The dots that lie along each ellipse are the observed data points. The scale at upper left, indicated with a short double headed arrow, reads: 0.1”. At upper right the orientation of the image is indicated with arrows, north is up and east is to the left. •Near-Infrared View of the Galactic Center. This image shows the inner 1 arcsecond, or 0.13 light-year, at the center of the Galaxy, as observed with the giant Keck Telescope. Tracks of the orbiting stars measured from 1995 to 2014 have been added to this “snapshot.” The stars are moving around the center very fast, and their tracks are all consistent with a single massive “gravitator” that resides in the very center of this image. (credit: modification of work by Andrea Ghez, UCLA Galactic Center Group, W.M. Keck Observatory Laser Team) Figure 25.19 Orbital Motions in the Milky Way. In panel (a), at top and labeled “Thin Disk”, shows the orbits of stars as blue concentric ellipses centered on a + sign indicating the galactic center. The orbits are in the same plane, labeled “Galactic plane”. In panel (b), at bottom and labeled: “Halo”, shows the orbits of stars as blue ellipses of many different sizes and orientations extending above and below the galactic plane and centered on a + sign indicating the galactic center. •How Objects Orbit the Galaxy. (a)In this image, you see stars in the thin disk of our Galaxy in nearly circular orbits. (b)In this image, you see the motion of stars in the Galaxy’s halo in randomly oriented and elliptical orbits. galaxie § Galaxie a galaxie 34 extragalaktické systémy •1. objev - 16. století - Magellanova mračna, dnes známo cca 100 miliard • •Hubbleova klasifikace (dle vzhledu) –E eliptické 13 % –S spirální 62 % –SO čočkovitý tvar 9 % –Ir nepravidelné 3 % • •13 % zbývajících se z této klasifikace vymyká - tzv. aktivní galaxie –Seyfertovy –rádiové galaxie –kvasary (QSO - quasi stellar object) Hubbleova klasifikace Spirální galaxie Eliptické galaxie Figure 26.8 Dwarf Elliptical Galaxy M32. This companion to the Andromeda Galaxy is, like most ellipticals, a featureless and uniform oval of light. Note that individual stars can be seen at the edges where the density of stars declines. •Dwarf Elliptical Galaxy. M32, a dwarf elliptical galaxy and one of the companions to the giant Andromeda galaxy M31. M32 is a dwarf by galactic standards, as it is only 2400 light-years across. (credit: NOAO/AURA/NSF) Figure 26.7 Elliptical Galaxies. Panel (a), at left, shows the giant elliptical ESO 325-G004, a large and nearly featureless oval of light with a bright nucleus. Panel (b), at right, shows an unnamed elliptical that has more structure within the otherwise featureless oval, suggesting a relatively recent formation from the collision of two spiral galaxies. •Elliptical Galaxies. (a)ESO 325-G004 is a giant elliptical galaxy. Other elliptical galaxies can be seen around the edges of this image. (b)This elliptical galaxy probably originated from the collision of two spiral galaxies. (credit a: modification of work by NASA, ESA, and The Hubble Heritage Team (STScI/AURA); credit b: modification of work by ESA/Hubble, NASA) Čočkovité galaxie Nepravidelné galaxie Figure 25.21 Monolithic Collapse Model for the Formation of the Galaxy. Panel 1 at upper left shows the gas cloud, drawn as a blue blob, at the beginning of its collapse. The axis of rotation (drawn in all four panels) is a vertical line above center with a counter-clockwise arrow around it indicating the direction of rotation. White arrows at the periphery of the cloud point toward the center illustrating the collapse. Panel 2 at upper right shows the gas cloud flattened a bit at the edges and thicker nearer the axis of rotation. Globular clusters are indicated as white dots outside the cloud. Panel 3 at lower left shows the cloud further flattened and continuing to collapse into a disk. Finally, panel 4 at lower right shows the galaxy much thinner, and now drawn in white to indicate that stars have formed in the disk. Globular clusters are evenly distributed around the galactic bulge. •Monolithic Collapse Model for the Formation of the Galaxy. According to this model, the Milky Way Galaxy initially formed from a rotating cloud of gas that collapsed due to gravity. Halo stars and globular clusters either formed prior to the collapse or were formed elsewhere. Stars in the disk formed later, when the gas from which they were made was already “contaminated” with heavy elements produced in earlier generations of stars. Figure 25.25 Collision of the Milky Way with Andromeda. In panel 1, at upper left, the Andromeda galaxy looms large in the night sky. In panel 2, at top center, the interaction has begun with the Milky Way and Andromeda becoming visibly distorted as Andromeda gets closer to us. In panel 3, at upper right, the sky is ablaze with star forming regions and a riot of dust clouds and star clusters. In panel 4, at lower left, the galaxies further lose their spiral shapes, but dust lanes and star formation persists. By panel 5, at lower center, the two galactic nuclei fill the sky. Finally, in panel 6 at lower right, the nuclei have merged into a huge elliptical mass of stars. •Collision of the Milky Way with Andromeda. In about 3 billion years, the Milky Way Galaxy and Andromeda Galaxy will begin a long process of colliding, separating, and then coming back together to form an elliptical galaxy. The whole interaction will take 3 to 4 billion years. These images show the following sequence: (1) In 3.75 billion years, Andromeda has approached the Milky Way. (2) New star formation fills the sky 3.85 billion years from now. (3) Star formation continues at 3.9 billion years. (4) The galaxy shapes change as they interact, with Andromeda being stretched and our Galaxy becoming warped, about 4 billion years from now. (5) In 5.1 billion years, the cores of the two galaxies are bright lobes. (6) In 7 billion years, the merged galaxies form a huge elliptical galaxy whose brightness fills the night sky. This artist’s illustrations show events from a vantage point 25,000 light-years from the center of the Milky Way. However, we should mention that the Sun may not be at that distance throughout the sequence of events, as the collision readjusts the orbits of many stars within each galaxy. (credit: NASA; ESA; Z. Levay, R. van der Marel, STScl; T. Hallas, and A. Mellinger) gal_evolve vývoj galaxií podle HDF Aktivní galaxie •rádiově tiché –linery, Seyfertovy, kvasary •rádiově hlučné –rádiové galaxie, blasary, OVV kvasary Figure 27.2 Photograph of a Typical Quasar. What looks like an ordinary star (arrowed) in this image is actually a distant quasi-stellar object, also known as a quasar. •Typical Quasar. The arrow in this image marks the quasar known by its catalog number, PKS 1117-248. Note that nothing in this image distinguishes the quasar from an ordinary star. Its spectrum, however, shows that it is moving away from us at a speed of 36% the speed of light, or 67,000 miles per second. In contrast, the maximum speed observed for any star is only a few hundred miles per second. (credit: modification of work by WIYN Telescope, Kitt Peak National Observatory, NOAO) Figure 27.5 Quasar Host Galaxies. These HST images reveal the details of the fainter “host” galaxies around quasars. The top left image shows a quasar at the heart of a spiral galaxy 1.4 billion light years away. The bottom left image shows a quasar at the center of an elliptical galaxy some 1.5 billion light years from Earth. The middle images show remote pairs of interacting galaxies, in which one of the galaxies harbors a quasar. Each of the images at right shows long tails of gas and dust streaming away from galaxies that contain a quasar. •Quasar Host Galaxies. The Hubble Space Telescope reveals the much fainter “host” galaxies around quasars. The top left image shows a quasar that lies at the heart of a spiral galaxy 1.4 billion light-years from Earth. The bottom left image shows a quasar that lies at the center of an elliptical galaxy some 1.5 billion light-years from us. The middle images show remote pairs of interacting galaxies, one of which harbors a quasar. Each of the right images shows long tails of gas and dust streaming away from a galaxy that contains a quasar. Such tails are produced when one galaxy collides with another. (credit: modification of work by John Bahcall, Mike Disney, NASA) Figure 26.11 Cepheid Variable Star in M100. In the background of this image is a portion of the galaxy M100. At center right is a small white box indicating the area that contains the variable star observed using the Hubble Space Telescope. Along the top of the image are three insets showing the star at three different times. From left: “May 4”, “May 9” and “May 31”. The star is significantly brighter in the May 31 image. •Cepheid Variable Star. In 1994, using the Hubble Space Telescope, astronomers were able to make out an individual cepheid variable star in the galaxy M100 and measure its distance to be 56 million light-years. The insets show the star on three different nights; you can see that its brightness is indeed variable. (credit: modification of work by Wendy L. Freedman, Observatories of the Carnegie Institution of Washington, and NASA/ESA) Figure 26.12 Type Ia Supernova. The very bright star to the left of center is a type Ia supernova at the outskirts of the spiral galaxy seen at upper right. •Type Ia Supernova. The bright object at the bottom left of center is a type Ia supernova near its peak intensity. The supernova easily outshines its host galaxy. This extreme increase and luminosity help astronomers use Ia supernova as standard bulbs. (credit: NASA, ESA, A. Riess (STScI)) Figure 27.15 In this plot the vertical axis is labeled “Black Hole Mass”. The scale goes from “No black hole” at bottom, “One million solar masses” in the middle and “One billion solar masses” at top. The horizontal axis is labeled: “Mass of Central Bulge”. The scale is arbitrary, with an arrow pointing to the right labeled “Increasing”. A straight white line is drawn from lower left to upper right with illustrations of galaxies along its length. At bottom left is a small spiral galaxy. Moving upward along the line, the galaxies increase in size as do the black dots at the center of each representing black holes. The final image at upper right is a very large elliptical with a very large black hole. •Relationship between Black Hole Mass and the Mass of the Host Galaxy. Observations show that there is a close correlation between the mass of the black hole at the center of a galaxy and the mass of the spherical distribution of stars that surrounds the black hole. That spherical distribution may be in the form of either an elliptical galaxy or the central bulge of a spiral galaxy. (credit: modification of work by K. Cordes, S. Brown (STScI)) Velkorozměrové struktury •galaxie jsou většinou ve skupinách •Místní skupina galaxií –Galaxie, M 31, M 33, LMC, SMC –průměr 800 kpc •kupy galaxií •buněčná struktura • • … konec Messierovy objekty katalog