Study Guide 3 Astronomy 104 Spring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
:KDW NLQGV RI REMHFWV OLH LQ WKH GLVN RI RXU JDOD[\" $ JDV DQG GXVW % RSHQ FOXVWHUV & 2 DQG % VWDUV ' ROG. DQG 0 VWDUV ( DOO RI WKH DERYH :KHUH DUH PRVW KHDY\ HOHPHQWV PDGH" $ LQ VWDUV DQG VXSHUQRYDH % LQ WKH %LJ %DQJ ZKHQ WKH XQLYHUVH ILUVW EHJDQ & LQ WKH LQWHUVWHOODU PHGLXP ' QRQH RI WKH DERYH ( DOO RI WKH DERYH :KDW LV WKH PRVW FRPPRQ IRUP RI JDV LQ WKH LQWHUVWHOODU PHGLXP" $ PROHFXODU KHOLXP % DWRPLF K\GURJHQ & PROHFXODU K\GURJHQ ' DWRPLF KHOLXP ( LRQL]HG K\GURJHQ &RPSDUHG ZLWK RXU 6XQ PRVW VWDUV LQ WKH KDOR DUH $ ROG UHG DQG EULJKW DQG KDYH IHZHU KHDY\ HOHPHQWV % \RXQJ EOXH DQG EULJKW DQG KDYH PXFK PRUH KHDY\ HOHPHQW PDWHULDO & ROG UHG DQG GLP DQG KDYH IHZHU KHDY\ HOHPHQWV ' ROG UHG DQG GLP DQG KDYH PXFK PRUH KHDY\ HOHPHQW PDWHULDO ( \RXQJ UHG DQG GLP DQG KDYH IHZHU KHDY\ HOHPHQWV :K\ GR ZH EHOLHYH RI WKH PDVV RI WKH 0LON\ :D\ LV LQ WKH IRUP RI GDUN PDWWHU" $ 2XU YLHZ RI GLVWDQW JDOD[LHV LV VRPHWLPHV REVFXUHG E\ GDUN EORWFKHV LQ WKH VN\ DQG ZH EHOLHYH WKHVH EORWFKHV DUH GDUN PDWWHU ORFDWHG LQ WKH KDOR % $OWKRXJK GDUN PDWWHU HPLWV QR YLVLEOH OLJKW LW FDQ EH VHHQ ZLWK UDGLR ZDYHOHQJWKV DQG VXFK REVHUYDWLRQV FRQILUP WKDW WKH KDOR LV IXOO RI WKLV PDWHULDO & 7KHRUHWLFDO PRGHOV RI JDOD[\ IRUPDWLRQ VXJJHVW WKDW D JDOD[\ FDQQRW IRUP XQOHVV LW KDV DW OHDVW WLPHV DV PXFK PDWWHU DV ZH VHH LQ WKH 0LON\ :D\ GLVN VXJJHVWLQJ WKDW WKH KDOR LV IXOO RI GDUN PDWWHU ' 7KH RUELWDO VSHHGV RI VWDUV IDU IURP WKH JDODFWLF FHQWHU DUH VXUSULVLQJO\ KLJK VXJJHVWLQJ WKDW WKHVH VWDUV DUH IHHOLQJ JUDYLWDWLRQDO HIIHFWV IURP XQVHHQ PDWWHU LQ WKH KDOR :KDW LV 6JU $ " $ D VRXUFH RI EULJKW ;UD\ HPLVVLRQ FRPLQJ IURP WKH HQWLUH FRQVWHOODWLRQ RI 6DJLWWDULXV % D VRXUFH WKDW LV EULJKW LQ WKH YLVLEOH ZDYHOHQJWKV LQ WKH FHQWHU RI RXU JDOD[\ & WKH EXOJH DW WKH FHQWHU RI RXU JDOD[\ ' D VRXUFH RI EULJKW UDGLR HPLVVLRQ LQ WKH FHQWHU RI RXU JDOD[\ ( WKH EULJKWHVW VWDU LQ WKH FRQVWHOODWLRQ 6DJLWWDULXV 7KH 6XQ LV ORFDWHG DW WKH HGJH RI WKH JDOD[\ DSSUR[LPDWHO\ OLJKW\HDUV IURP WKH JDODFWLF FHQWHU
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
7KH YHU\ ODUJHVW JDOD[LHV DUH RI ZKLFK W\SH $ VSLUDO % HOOLSWLFDO & LUUHJXODU ' DOO WKH VDPH 7KH PRVW ZLGHO\ DFFHSWHG YDOXH IRU +XEEOHV FRQVWDQW LV $ NPVHF0SF % NPVHF0SF & NPVHF0SF ' NPVHF0SF 7KH 'RSSOHU VKLIW RI OLJKW IURP RWKHU JDOD[LHV DUH $ PRVWO\ EOXH VKLIWHG % HYHQO\ GLVWULEXWHG EHWZHHQ UHG DQG EOXH VKLIWV & PRVWO\ UHG VKLIWHG ' XVXVDOO\ ]HUR $ SURWRJDODFWLF FORXG ZLWK YHU\ OLWWOH DQJXODU PRPHQWXP LV PRUH OLNHO\ WR IRUP DQ HOOLSWLFDO JDOD[\ WKDQ D VSLUDO JDOD[\