Kauv vs Elliptical Galaxies
Galaxy yog cov khoom loj ntawm cov hnub qub. Lawv kuj muaj cov huab cua loj interstellar hu ua nebulae. Cov hnub qub loj ntawm cov hnub qub no tsis tau txheeb xyuas thiab kawm tau zoo kom txog rau thaum lig 18th thiab 19th centuries. Txawm li ntawd los cov no raug suav hais tias yog nebulae. Cov ntawv sau hnub qub no nyob ib puag ncig ntawm Milky Way, uas yog peb cov hnub qub sau. Feem ntau ntawm cov khoom nyob rau hauv lub ntuj tsaus ntuj yog nyob rau hauv lub galaxy no tab sis, yog hais tias koj saib ze, koj muaj peev xwm txheeb xyuas lub ntxaib galaxy ntawm lub Milky Way; Lub Andromeda Galaxy. Txawm li cas los xij, qhov txwv tsis pub muaj zog ntawm lub koob yees duab tso cai tsuas yog me ntsis nkag mus rau hauv lub ntuj tob; yog li ntawd, kev nkag siab ntawm cov khoom astronomical nyob deb no tsis meej. Kev piav qhia tiag tiag rau hauv cov qauv ntawm lub cev astronomical zoo kawg nkaus tuaj tom qab ntau.
Nyob rau hauv lub xyoo pua 20th, Edwin Hubble tau kawm ntau yam ntawm galaxies thiab muab faib raws li lawv cov duab thiab cov qauv. Ob pawg loj ntawm lub galaxies yog kauv thiab lub elliptical galaxies. Raws li cov duab ntawm cov kauv caj npab, kauv galaxies tau muab faib ua ob pawg raws li Kauv Galaxies (S) thiab Barred Spiral Galaxies (SB). (Saib cov duab hauv qab no)
Kauv Galaxies
Kauv galaxies muaj npe nyob rau hauv txoj kev no vim yog lub caj npab winding kom pom tseeb hauv hom galaxies. Cov galaxies no yog tiaj tus disk zoo li lub voj voog ncig thiab qhov chaw bulging. Cov kauv galaxies yog hom galaxies ntau tshaj plaws nyob rau hauv lub ntiaj teb (ze li 75%), thiab peb tus kheej galaxy, Milky Way, kuj yog ib lub kauv galaxy. Cov kauv galaxies yog thawj hom galaxies uas tib neeg pom, thiab qhov ntawd yog peb cov galaxy uas nyob sib ze, Andromeda.
Feem ntau, kauv galaxies muaj kwv yees li 10 9 rau 1011 hnub ci huab hwm coj thiab muaj luminosity ntawm 10 8 thiab 2×10 10 hnub ci luminosity. Txoj kab uas hla ntawm cov kauv galaxies tuaj yeem sib txawv ntawm 5 kilo parsecs txog 250 kilo parsecs. Lub disk ntawm cov kauv galaxies muaj cov hluas, Population I hnub qub, whereas lub hauv paus bulge thiab lub halo muaj ob Population I thiab Population II hnub qub.
Txoj kev xav, kauv caj npab yog tsim los ntawm cov nthwv dej ntom ntom ntws los ntawm galaxy disk. Cov nthwv dej ntom ntom no ua rau thaj chaw ntawm cov hnub qub tsim thiab cov hnub qub ci ntsa iab nyob rau hauv qhov ntom ntom hauv cov cheeb tsam no ua rau muaj qhov pom kev zoo dua ntawm thaj chaw.
Ob pawg ntawm cov kauv galaxies, Kauv galaxies thiab Barred Kauv Galaxies tau muab faib ua peb subclasses txhua, raws li cov duab thiab cov qauv ntawm cov caj npab kauv. Sa, Sb thiab Sc yog Kauv galaxies subclasses, thaum SBa, SBb thiab SBc yog txwv kauv subclasses.
Elliptical Galaxies
Elliptical galaxies muaj cov yam ntxwv oval zoo nyob rau hauv lawv cov cheeb tsam sab nrauv thiab ib qho kev tsim xws li caj npab kauv tsis pom. Txawm hais tias elliptical galaxies tsis pom cov qauv sab hauv, lawv kuj muaj cov nucleus denser. Kwv yees li 20% ntawm cov galaxies hauv lub ntiaj teb yog elliptical galaxies.
Ib lub galaxy elliptical tej zaum yuav muaj 10 5 rau 1013 hnub ci ntau thiab tuaj yeem tsim luminosity ntawm 3 × 10 5 rau 1011 hnub ci luminosities. Txoj kab uas hla yuav nyob ntawm 1 kilo parsec mus rau 200 kilo parsec. Lub galaxy elliptical muaj qhov sib xyaw ntawm Population I thiab Population II hnub qub hauv lub cev.
Elliptical galaxies muaj yim subclasses E0-E7, qhov twg eccentricity nce nyob rau hauv kev coj ntawm E0 rau E7, thiab E0 yog roughly spherical nyob rau hauv cov duab.
Dab tsi yog qhov txawv ntawm Kauv thiab Elliptical Galaxies?
• Kauv galaxies muaj lub tiaj tiaj zoo li cov duab thiab qhov chaw bulging nrog kauv caj npab muaj cov disk. Elliptical galaxies yog ellipsoids uas tsis muaj qhov pom tseeb hauv cov qauv.
• Kem galaxies muaj cov nucleus ntom ntom ntom thiab thaj av ntawm cov hnub qub bulging sab nraud los ntawm disks thiab, yog li ntawd, hu ua lub central su. Elliptical galaxies kuj muaj qhov chaw ntom ntom, tab sis lawv tsis tawm ntawm lub cev ntawm lub galaxy.
• Kauv galaxies yog hom galaxies ntau tshaj plaws thiab muaj peb lub quarters ntawm tag nrho cov galaxy cov pejxeem. Elliptical galaxies yog qhov tsawg heev thiab tsuas muaj ib feem tsib ntawm cov neeg galaxy xwb.
• Kauv galaxies muaj lub hnub qub tsim thaj tsam hauv caj npab kauv; yog li ntawd muaj feem coob Population kuv hnub qub. Muaj ob qho tib si Population I thiab II hnub qub nyob rau hauv lub halo thiab lub hauv paus bulge. Elliptical galaxies, tsis muaj qauv muaj kev sib xyaw ntawm Population I thiab II hnub qub.
