Yog koj saib ze ntawm lub ntuj tsaus, nws yooj yim kom pom tias cov hnub qub saib peb txawv xim. Bluish, dawb, liab, lawv ci sib npaug los yog flicker zoo li Christmas tsob ntoo garland. Nyob rau hauv ib lub telescope, xim sib txawv tau pom ntau dua. Yog vim li cas rau qhov sib txawv no nyob rau hauv qhov kub ntawm lub photosphere. Thiab, tsis zoo li qhov kev xav, qhov kub tshaj plaws tsis yog liab, tab sis xiav, dawb-xiav thiab dawb hnub qub. Tab sis ua ntej ua ntej.
Spectral classification
hnub qub yog cov pa roj kub loj loj. Txoj kev uas peb pom lawv los ntawm lub ntiaj teb nyob ntawm ntau yam tsis muaj. Piv txwv li, cov hnub qub tsis tau twinkle. Nws yog ib qho yooj yim heev kom ntseeg tau qhov no: nws txaus los nco txog Hnub. Cov nyhuv flickering tshwm sim vim qhov tseeb tias lub teeb los ntawm lub cev cosmic rau peb kov yeej lub hnub qub nruab nrab, tag nrho ntawm plua plav thiab roj. Lwm qhov yog xim. Nws yog qhov tshwm sim ntawm cov cua kub ntawm lub plhaub (tshwj xeeb tshaj yog cov photosphere) rau qee qhov kub. Cov xim tiag tiag yuav txawv ntawm qhov pom, tab sis qhov sib txawv feem ntau me me.
Hnub no, Harvard spectral faib cov hnub qub tau siv thoob plaws ntiaj teb. Nws tshwm simqhov kub thiab txias yog nyob ntawm daim ntawv thiab qhov sib txheeb ntawm cov kab ntawm cov spectrum. Txhua chav kawm sib raug rau cov hnub qub ntawm ib qho xim. Kev faib tawm yog tsim los ntawm Harvard Observatory hauv 1890-1924.
Ib shaved Englishman Chewed hnub zoo li Carrots
Muaj xya lub ntsiab spectral: O-B-A-F-G-K-M. Cov kab ke no qhia txog qhov txo qis hauv qhov kub thiab txias (los ntawm O rau M). Kom nco ntsoov, muaj cov qauv mnemonic tshwj xeeb. Nyob rau hauv Lavxias teb sab, ib tug ntawm lawv suab zoo li no: "Ib tug Shaved Englishman Chewed hnub zoo li Carrots." Ob ntxiv ntxiv rau cov chav kawm no. Cov tsiaj ntawv C thiab S qhia txog qhov txias luminaries nrog hlau oxide bands hauv spectrum. Cia wb mus saib cov chav hnub qub:
- Class O yog tus yam ntxwv ntawm qhov kub siab tshaj plaws (ntawm 30 txog 60 txhiab Kelvin). Hnub qub ntawm hom no tshaj lub hnub nyob rau hauv loj los ntawm 60, thiab nyob rau hauv lub vojvoog - los ntawm 15 zaug. Lawv pom xim yog xiav. Nyob rau hauv cov nqe lus ntawm luminosity, lawv ua ntej ntawm peb lub hnub qub los ntawm ntau tshaj li ib lab lub sij hawm. Lub hnub qub xiav HD93129A, nyob rau hauv chav kawm no, yog tus cwj pwm los ntawm ib qho ntawm cov luminosity siab tshaj plaws ntawm cov paub lub cev cosmic. Raws li qhov ntsuas no, nws yog ua ntej ntawm Lub Hnub los ntawm 5 lab lub sijhawm. Lub hnub qub xiav nyob ntawm qhov deb ntawm 7.5 txhiab lub teeb xyoo ntawm peb.
- Class B muaj qhov kub ntawm 10-30 txhiab Kelvin, qhov loj 18 npaug ntau dua li lub hnub. Cov no yog cov hnub qub dawb-xiav thiab dawb hnub qub. Lawv lub vojvoog yog 7 npaug loj dua lub hnub.
- Class A yog qhov ntsuas kub ntawm 7.5-10 txhiab Kelvin,Lub vojvoog thiab qhov loj tshaj 2.1 thiab 3.1 npaug, feem, qhov zoo sib xws ntawm lub hnub. Cov no yog cov hnub qub dawb.
- Class F: kub 6000-7500 K. Mass loj dua lub hnub los ntawm 1.7 npaug, lub vojvoog - los ntawm 1.3. Los ntawm lub ntiaj teb, cov hnub qub no tseem saib dawb, lawv cov xim tiag tiag yog daj dawb.
- Class G: kub 5-6 txhiab Kelvin. Lub hnub belongs rau chav kawm no. Qhov tseeb thiab tseeb xim ntawm cov hnub qub yog daj.
- Class K: qhov kub thiab txias 3500-5000 K. Lub vojvoog thiab qhov loj yog tsawg dua hnub ci, lawv yog 0.9 thiab 0.8 ntawm qhov sib thooj ntawm lub hnub qub. Pom los ntawm lub ntiaj teb, cov xim ntawm cov hnub qub yog daj-txiv kab ntxwv.
- Class M: kub 2-3.5 txhiab Kelvin. Loj thiab vojvoog - 0.3 thiab 0.4 los ntawm cov tsis zoo sib xws ntawm lub hnub. Los ntawm qhov chaw ntawm peb ntiaj chaw, lawv zoo li liab-txiv kab ntxwv. Beta Andromedae thiab Alpha Chanterelles yog nyob rau hauv chav kawm M. Lub hnub qub ci liab uas paub ntau yog Betelgeuse (Alpha Orionis). Nws yog qhov zoo tshaj los nrhiav nws saum ntuj nyob rau lub caij ntuj no. Lub hnub qub liab nyob saum toj thiab me ntsis rau sab laug ntawm Orion txoj siv.
Txhua chav kawm muab faib ua subclasses ntawm 0 txog 9, uas yog, los ntawm kub tshaj mus rau txias tshaj plaws. Cov naj npawb ntawm cov hnub qub qhia tau hais tias yog ib hom spectral thiab qib ntawm cov cua sov ntawm photosphere hauv kev sib piv nrog rau lwm cov luminaries hauv pab pawg. Piv txwv li, lub hnub nyob rau hauv chav kawm G2.
Visual whites
Yog li, hnub qub chav B txog F tuaj yeem saib dawb ntawm lub ntiaj teb. Thiab tsuas yog cov khoom uas yog A-hom tiag tiag muaj cov xim no. Yog li ntawd, lub hnub qub Saif (constellation Orion) thiab Algol (beta Perseus) rau ib tug neeg soj ntsuam tsis armed nrog ib tug telescope yuav zoo li.dawb. Lawv nyob rau hauv chav kawm spectral B. Lawv cov xim tseeb yog xiav-dawb. Tsis tas li ntawd tshwm sim dawb yog Mythrax thiab Procyon, lub hnub qub ci tshaj plaws nyob rau hauv lub hnub qub kos duab ntawm Perseus thiab Canis Minor. Txawm li cas los xij, lawv cov xim tiag tiag ze dua rau xim daj (qib F).
Vim li cas cov hnub qub thiaj li dawb rau cov neeg soj ntsuam hauv ntiaj teb? Cov xim yog distorted vim qhov deb heev sib cais peb ntiaj chaw los ntawm cov khoom zoo sib xws, nrog rau cov huab voluminous ntawm plua plav thiab roj, feem ntau pom nyob rau hauv qhov chaw.
Klass A
Cov hnub qub dawb yog qhov tsis muaj qhov kub thiab txias li cov neeg sawv cev ntawm cov chav kawm O thiab B. Spectral class A hnub qub loj dua lub hnub. Lawv cov luminosity kuj ntau dua - txog 80 npaug.
Nyob rau hauv lub spectra ntawm A-hnub qub, hydrogen kab ntawm Balmer series tau hais tau zoo. Cov kab ntawm lwm cov ntsiab lus yog qhov tsis muaj zog, tab sis lawv tseem ceeb dua thaum koj txav los ntawm subclass A0 mus rau A9. Giants thiab supergiants teej tug mus rau spectral chav kawm ntawv A yog tus yam ntxwv los ntawm me ntsis tsawg pronounced hydrogen kab tshaj lub ntsiab ua raws hnub qub. Nyob rau hauv rooj plaub ntawm cov luminaries no, cov hlau hnyav hnyav dhau los ua pom tau ntau dua.
Muaj ntau lub hnub qub peculiar uas yog nyob rau hauv chav kawm spectral A. Lub sij hawm no yog hais txog cov luminaries uas muaj cov yam ntxwv ntawm cov spectrum thiab lub cev tsis zoo, uas ua rau nws nyuaj rau kev faib lawv. Piv txwv li, tsis tshua muaj hnub qub ntawm Bootes lambda hom yog qhov tsis muaj hlau hnyav thiab kev sib hloov qeeb heev. Peculiar luminaries kuj suav nrog dwarfs dawb.
Class A belongs rau cov khoom ci ntsa iab hmo ntujntuj ceeb tsheej, zoo li Sirius, Mencalinan, Alioth, Castor thiab lwm yam. Cia peb paub lawv zoo dua.
Alpha Canis Major
Sirius yog qhov ci tshaj plaws, txawm tias tsis yog qhov ze tshaj plaws, lub hnub qub saum ntuj. Qhov kev ncua deb ntawm nws yog 8.6 lub teeb xyoo. Rau cov neeg soj ntsuam hauv ntiaj teb, nws zoo li ci ntsa iab vim tias nws muaj qhov loj me thiab tseem tsis tau tshem tawm deb npaum li ntau lwm yam khoom loj thiab ci. Lub hnub qub ze tshaj plaws rau lub hnub yog Alpha Centauri. Sirius yog qhov thib tsib ntawm daim ntawv teev npe no.
Nws belongs rau lub hnub qub Canis Major thiab yog ib qho ntawm ob lub ntsiab lus. Sirius A thiab Sirius B tau sib cais los ntawm 20 astronomical units thiab tig nrog lub sijhawm tsawg dua 50 xyoo. Thawj feem ntawm lub kaw lus, lub hnub qub tseem ceeb, yog nyob rau hauv chav kawm spectral A1. Nws qhov loj yog ob npaug ntawm lub hnub, thiab nws lub vojvoog yog 1.7 npaug. Nws yog tus uas tuaj yeem pom ntawm qhov muag liab qab ntawm lub ntiaj teb.
Qhov thib ob ntawm lub kaw lus yog lub ntsej muag dawb. Lub hnub qub Sirius B yuav luag sib npaug rau peb cov luminary hauv huab hwm coj, uas tsis yog ib txwm zoo rau cov khoom zoo li no. Feem ntau, dwarfs dawb yog tus cwj pwm los ntawm qhov loj ntawm 0.6-0.7 hnub ci. Tib lub sijhawm, qhov ntev ntawm Sirius B yog ze rau cov neeg hauv ntiaj teb. Nws tau xav tias qhov dawb dwarf theem pib rau lub hnub qub no txog 120 lab xyoo dhau los. Thaum Sirius B tau nyob rau ntawm qhov sib lawv liag, nws yog ib qho luminary uas muaj 5 lub hnub ci loj thiab koom rau hauv hom spectral B.
Sirius A, raws li cov kws tshawb fawb, yuav txav mus rau theem tom ntej ntawm kev hloov pauv hauv kwv yees li 660 lab xyoo. CesNws yuav tig mus rau hauv ib tug loj loj liab, thiab ib tug me ntsis tom qab - mus rau hauv ib tug dawb dwarf, zoo li nws tus khub.
Alpha Eagle
Zoo li Sirius, ntau lub hnub qub dawb, uas nws cov npe tau muab hauv qab no, paub zoo tsis yog rau cov tib neeg uas nyiam hnub qub vim lawv qhov ci ntsa iab thiab nquag hais nyob rau hauv nplooj ntawv ntawm cov ntaub ntawv keeb kwm science. Altair yog ib qho ntawm cov luminaries. Alpha Eagle pom, piv txwv li, hauv Ursula le Guin thiab Steven King. Nyob rau hauv lub ntuj hmo ntuj, lub hnub qub no pom meej meej vim nws ci ntsa iab thiab ze ze. Qhov kev ncua deb ntawm lub hnub thiab Altair yog 16.8 lub teeb xyoo. Ntawm cov hnub qub ntawm spectral class A, tsuas yog Sirius nyob ze rau peb.
Altair yog 1.8 npaug loj li lub hnub. Nws cov yam ntxwv feature yog kev sib hloov ceev heev. Lub hnub qub ua rau ib qho kev sib hloov nyob ib ncig ntawm nws cov axis hauv tsawg tshaj li cuaj teev. Kev sib hloov ceev nyob ze ntawm txoj kab nruab nrab yog 286 km / s. Yog li ntawd, lub "nimble" Altair yuav flattened los ntawm tus ncej. Tsis tas li ntawd, vim yog cov duab elliptical, qhov kub thiab qhov ci ntawm lub hnub qub txo qis los ntawm cov ncej mus rau txoj kab nruab nrab. Cov nyhuv no hu ua "gravitational darkening".
Lwm qhov tshwj xeeb ntawm Altair yog tias nws qhov ci ntsa iab hloov pauv lub sijhawm. Nws hais txog qhov sib txawv ntawm Shield delta type.
Alpha Lyra
Vega yog lub hnub qub kawm tshaj plaws tom qab Hnub. Alpha Lyrae yog thawj lub hnub qub kom muaj nws qhov kev txiav txim siab. Nws kuj tau los ua tus thib ob luminary tom qab lub hnub, ntes nyob rau hauv daim duab. Vega kuj yog thawj hnub qub uas cov kws tshawb fawb ntsuas qhov kev ncua deb siv txoj kev parlax. Rau lub sijhawm ntev, qhov ci ntawm lub hnub qub raug coj los ua 0 thaum txiav txim siab qhov loj ntawm lwm yam khoom.
Alpha Lyra paub zoo rau ob qho tib si amateur astronomer thiab cov neeg soj ntsuam yooj yim. Nws yog lub thib tsib ci ntsa iab ntawm cov hnub qub, thiab suav nrog lub caij ntuj sov daim duab peb sab asterism nrog rau Altair thiab Deneb.
Qhov deb ntawm lub hnub mus rau Vega yog 25.3 lub teeb xyoo. Nws lub voj voog kab nruab nrab thiab qhov loj yog 2.78 thiab 2.3 npaug loj dua li qhov tsis sib xws ntawm peb lub hnub qub, raws li. Cov duab ntawm lub hnub qub nyob deb ntawm kev ua lub pob zoo meej. Txoj kab uas hla ntawm txoj kab nruab nrab yog pom tau tias loj dua ntawm cov ncej. Qhov laj thawj yog qhov kev sib hloov loj loj. Nyob rau ntawm txoj kab nruab nrab, nws ncav cuag 274 km / s (rau lub hnub, qhov ntsuas no yog me ntsis ntau tshaj ob kilometers ib ob).
Ib qho ntawm Vega qhov tshwj xeeb yog cov hmoov av uas nyob ib puag ncig nws. Piv txwv li, nws tshwm sim los ntawm ib tug loj tus naj npawb ntawm kev sib tsoo ntawm comets thiab meteorites. Cov plua plav disk tig ncig lub hnub qub thiab ua kom sov los ntawm nws cov hluav taws xob. Yog li ntawd, qhov kev siv ntawm cov hluav taws xob infrared ntawm Vega nce. Tsis ntev tas los no, asymmetries tau pom nyob rau hauv lub disk. Lawv cov lus piav qhia yog tias lub hnub qub muaj tsawg kawg yog ib lub ntiaj teb.
Alpha Gemini
Qhov thib ob brightest khoom nyob rau hauv lub constellation Gemini yog Castor. Nws, zoo li yav dhau los luminaries, belongs rau chav kawm spectral A. Castor yog ib lub hnub qub ci tshaj plaws nyob rau hmo ntuj. Hauv daim ntawv teev npe sib raug, nws nyob ntawm 23rd qhov chaw.
Castor yog ntau lub kaw lus uas muaj rau lub Cheebtsam. Ob lub ntsiab tseem ceeb (Castor A thiab Castor B) tignyob ib ncig ntawm qhov chaw nruab nrab ntawm pawg nrog lub sijhawm ntawm 350 xyoo. Txhua ntawm ob lub hnub qub yog spectral binary. Cov Cheebtsam ntawm Castor A thiab Castor B yog qhov kaj tsawg thiab xav tias yog hom spectral M.
Castor C tsis txuas nrog lub kaw lus tam sim ntawd. Thaum pib, nws tau raug xaiv los ua lub hnub qub ywj pheej YY Gemini. Nyob rau hauv tus txheej txheem ntawm kev tshawb fawb cheeb tsam ntawm lub ntuj, nws tau paub tias lub luminary no yog lub cev txuas nrog lub Castor system. Lub hnub qub revolves nyob ib ncig ntawm qhov chaw ntawm huab hwm coj mus rau tag nrho cov Cheebtsam nrog lub sij hawm ntawm ob peb kaum txhiab xyoo thiab kuj yog ib tug spectral binary.
Beta Aurigae
Auriga lub hnub qub kos duab suav nrog txog 150 "cov ntsiab lus", feem ntau yog cov hnub qub dawb. Cov npe ntawm cov luminaries yuav hais me ntsis rau ib tug neeg nyob deb ntawm astronomy, tab sis qhov no tsis cuam tshuam los ntawm lawv qhov tseem ceeb rau kev tshawb fawb. Cov khoom ci ntsa iab tshaj plaws nyob rau hauv cov qauv xilethi-aus, koom nrog hauv chav kawm spectral A, yog Mencalinan lossis Beta Aurigae. Lub npe ntawm lub hnub qub hauv Arabic txhais tau tias "lub xub pwg ntawm tus tswv ntawm lub reins."
Menkalinan - triple system. Nws ob lub ntsiab lus yog subgiants ntawm spectral class A. Qhov ci ntsa iab ntawm txhua tus ntawm lawv tshaj qhov zoo sib xws ntawm lub hnub los ntawm 48 zaug. Lawv raug cais los ntawm qhov deb ntawm 0.08 astronomical units. Qhov thib peb tivthaiv yog ib tug liab dwarf nyob deb ntawm 330 AU los ntawm khub. e.
Epsilon Ursa Major
Lub brightest "point" nyob rau hauv tej zaum lub constellation nto moo tshaj plaws nyob rau hauv sab qaum teb ntuj (Ursa Major) yog Aliot, kuj muab cais raws li chav kawm ntawv A. Qhov tseeb magnitude yog 1.76. Lub hnub qub ci ntsa iab tshaj plaws yuav siv 33rd qhov chaw. Alioth nkag mus rau Big Dipper asterism thiab nyob ze rau lub tais dua li lwm cov luminaries.
Aliot's spectrum yog tus cwj pwm los ntawm cov kab txawv txawv nrog lub sijhawm 5.1 hnub. Nws yog assumed tias cov yam ntxwv yog txuam nrog lub zog ntawm magnetic teb ntawm lub hnub qub. Kev hloov pauv hauv cov spectrum, raws li cov ntaub ntawv tsis ntev los no, tuaj yeem tshwm sim vim qhov chaw ze ntawm lub cev cosmic nrog qhov loj ntawm yuav luag 15 Jupiter pawg. Txawm hais tias qhov no yog li ntawd tseem yog qhov tsis paub. Nws, zoo li lwm yam zais cia ntawm cov hnub qub, astronomers sim nkag siab txhua hnub.
Dwarfs dawb
Zaj dab neeg hais txog cov hnub qub dawb yuav ua tsis tiav yog tias peb tsis hais txog theem ntawm kev hloov pauv ntawm cov hnub qub, uas tau xaiv los ua "dawb dwarf". Cov khoom zoo li no tau txais lawv lub npe vim qhov tseeb tias thawj zaug pom ntawm lawv tau koom rau hauv chav kawm spectral A. Nws yog Sirius B thiab 40 Eridani B. Niaj hnub no, cov neeg saib xyuas dawb hu ua ib qho kev xaiv rau theem kawg ntawm lub hnub qub lub neej.
Cia peb nyob kom ntxaws ntxiv ntawm lub neej voj voog ntawm cov luminaries.
Star evolution
Hnub qub tsis yug hauv ib hmo: ib qho ntawm lawv mus dhau ntau theem. Ua ntej, huab cua ntawm cov pa thiab plua plav pib poob qis los ntawm nws tus kheej lub zog gravitational. Maj mam, nws yuav siv lub pob, thaum lub zog ntawm lub ntiajteb txawj nqus hloov mus rau hauv tshav kub - qhov kub ntawm cov khoom nce. Nyob rau lub sijhawm thaum nws nce mus txog tus nqi ntawm 20 lab Kelvin, cov tshuaj tiv thaiv nuclear pib pib. Qhov no yog qhov pib ntawm lub neej ntawm lub hnub qub puv puv.
Feem ntau ntawm cov sij hawm cov luminaries siv rau lub ntsiab sib lawv liag. Cov tshuaj tiv thaiv tas li mus rau hauv lawv lub plabhydrogen voj voog. Qhov kub ntawm lub hnub qub yuav txawv. Thaum tag nrho cov hydrogen nyob rau hauv lub nucleus xaus, ib theem tshiab ntawm evolution pib. Tam sim no helium yog roj. Nyob rau tib lub sijhawm, lub hnub qub pib nthuav dav. Nws luminosity nce, thaum qhov kub thiab txias, ntawm qhov tsis sib xws, txo. Lub hnub qub tawm ntawm qhov tseem ceeb thiab dhau los ua tus loj loj.
Qhov loj ntawm helium core maj mam nce, thiab nws pib ntsws hauv nws qhov hnyav. Cov liab loj theem xaus sai dua li yav dhau los. Txoj kev uas ntxiv evolution yuav mus nyob ntawm qhov pib loj ntawm cov khoom. Cov hnub qub qis nyob rau theem loj loj liab pib o. Raws li qhov tshwm sim ntawm cov txheej txheem no, cov khoom tso nws cov plhaub. Ib tug planetary nebula thiab ib tug liab qab core ntawm ib lub hnub qub yog tsim. Nyob rau hauv xws li ib tug nucleus, tag nrho cov fusion tshwm sim tiav. Nws yog hu ua helium dawb dwarf. Ntau cov liab loj loj (txog ib qho kev txwv) hloov mus rau hauv cov pa roj carbon dawb dwarfs. Lawv muaj cov ntsiab lus hnyav dua li helium hauv lawv cov cores.
Ntse
dwarfs dawb yog lub cev, hauv pawg, raws li txoj cai, ze rau lub hnub. Nyob rau tib lub sijhawm, lawv qhov loj me sib haum rau lub ntiaj teb. Lub colossal ceev ntawm cov cosmic lub cev thiab cov txheej txheem ua qhov chaw nyob rau hauv lawv qhov tob yog inexplicable los ntawm qhov pom ntawm classical physics. Cov lus zais ntawm cov hnub qub tau tshwm sim los ntawm quantum mechanics.
Cov khoom ntawm cov dwarfs dawb yog electron-nuclear plasma. Nws yuav luag tsis yooj yim sua kom tsim nws txawm nyob hauv chav kuaj. Yog li ntawd, ntau yam ntawm cov khoom no tseem tsis nkag siab.
Txawm tias koj kawm cov hnub qub txhua hmo, koj yuav tsis tuaj yeem ntes tau tsawg kawg yog ib lub ntsej muag dawb uas tsis muaj cov cuab yeej tshwj xeeb. Lawv qhov luminosity tsawg dua li lub hnub. Raws li cov kws tshawb fawb, dwarfs dawb muaj li ntawm 3 txog 10% ntawm tag nrho cov khoom hauv Galaxy. Txawm li cas los xij, txog niaj hnub no, tsuas yog cov uas tau pom muaj nyob tsis pub dhau 200-300 parsecs los ntawm lub ntiaj teb.
Dwarfs dawb txuas ntxiv mus. Tam sim ntawd tom qab tsim, lawv muaj qhov kub thiab txias, tab sis txias sai. Ob peb kaum txhiab plhom xyoo tom qab tsim, raws li txoj kev xav, tus neeg ntsiaj dawb hloov mus ua ib lub ntsej muag dub - lub cev uas tsis pom lub teeb pom kev.
Dawb, liab lossis xiav lub hnub qub rau cov neeg soj ntsuam sib txawv ntawm cov xim. Cov astronomer saib tob. Xim rau nws tam sim ntawd qhia ntau txog qhov kub thiab txias, qhov loj thiab qhov loj ntawm cov khoom. Lub hnub qub xiav lossis ci xiav yog lub pob kub loj, nyob deb ntawm lub hnub nyob rau txhua qhov kev hwm. Dawb luminaries, piv txwv ntawm cov uas tau piav nyob rau hauv tsab xov xwm, yog me ntsis me. Cov lej hnub qub hauv ntau phau ntawv teev npe kuj qhia cov kws tshaj lij, tab sis tsis yog txhua tus. Ntau cov ntaub ntawv hais txog lub neej ntawm cov khoom nyob deb ntawm qhov chaw tseem tsis tau piav qhia, lossis tseem tsis tau pom dua.
