Astronomska opazovanja:

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Astronomska opazovanja od merjenja oddaljenosti
do fizike in obratno

• pri Soncu ni teav
• oddaljenost d150x106 km
• gostota sv. toka ob Zemlji j1.4kW/m2
• torej moc L 4pd2 j 4x1026 W
• kot, ki ga z Zemlje oklepa Soncev polmer f0.25o
• torej velikost Ro f d 7x105 km
• Zemlja obkroi Sonce v enem letu
• s 3. Keplerjevim zakonom, masa Sonca Mo 2x1030
  kg

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Kaj pa za druge zvezde?
Efektivno temperaturo se da meriti iz barv in
podrobnosti v spektru.
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A8V
8250K, Z/Zo0.0, logg4.0
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Poleg temperature bi bilo koristno poznati tudi
velikost in izsev zvezde.
r f d L j 4pd2
Za oboje potrebujemo razdaljo d, poleg tega so
zvezde skoraj tockaste Sonce na d 10 sv. let
f0.0016 ", Betelgeza vec, a to je izjema...
Polmer zvezd lahko izracunamo, ce poznamo L in
T L4pr2sT4
Obicajni nacin merjenja razdalj zvezd je metoda
trigonometricne paralakse, ki izkorica kroenja
naega opazovalica (Zemlje) okoli Sonca. Vendar
je amplituda premikov zvezd majhna 1" za d1 pc
(3.3 sv. leta), le 0.01" za d100 pc (330 sv.
let).
Opazovanja z Zemlje (0.03", usmerjena),
Hipparcos (0.003", vse do 10m), GAIA
(0.00001", vse do 20m).
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Pogost trik opazujemo zvezdno kopico, vse njene
zvezde so na prakticno enaki razdalji in so enako
stare.
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H-R diagram
Kaj pa starost, masa in kemicna sestava zvezd?
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Zvezda clan fizicne dvojnice.
a3 / P2 G(M1M2)/4p2
Sonce Ro 7x108 m Mo 2x1030 kg do
1.5x1011m 214 Ro
a do P/1 leto2/3 (M1M2)/Mo1/3
0.5 Ro P/1 ura2/3 (M1M2)/Mo1/3
ce relativni tir krog v1 2pa1/P 30
km/s P/1 leto-1/3 (M1/Mo) (M1M2)/Mo-2/3
611 km/s P/1 ura-1/3 (M1/Mo) (M1M2)/Mo-2/3
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Enacba za veliko polos tira (a) pove, da je
zvezdi na nebu teko lociti ce P 10 let,
M1M21Mo , d100 pc gtgtgt f a/d 0.046"
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Astrometric and resolved binaries
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Fotometricna opazovanja na Crnem Vrhu, in treh
observatorijih v Italiji.
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Spektroskopska opazovanja na observatoriju v
Asiagu (Italija).
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GKDra
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GK Draconis d Scuti variability
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GAIA and the eclipsing binaries
Asiago
Hipparcos
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a 15.06 /- 0.08 RO
M1 1.30 /- 0.02 Mo M2 1.28 /- 0.02 Mo
R1 1.40 /- 0.02 Ro R2 1.14 /- 0.03 Ro
T1 6460 /- 50 K T2 6415 /- 50 K
Mbol, 1 3.60 /- 0.04 Mbol, 2 4.04 /- 0.05
sHP 0.009 mag sVT 0.10 mag sBT 0.09 mag
sRV 1.5, 2.5 km/sec
66 /- 4 pc Hipparcos
distance 60 /- 3 pc Asiago/GAIA
62 /- 2 pc Marshall et al.
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orbital period actual sampling with GAIA
Scanning law courtesy D. Katz
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spectra extraction

• crowding
• resolution

HIP 46241
res 18100
courtesy Toma Tomov (Torun, Poland)
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interpretation also automatic
2 posters

• A. Pra spectroscopyphotometry
• no human intervention, 35sec/object
• P. Niarchos photometry

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Binaries star parameters distance
Case of bright stars (Vlt15)
Errors on single star parameters from
astrometry, photometry spectroscopy Tefflt50K,
log(g)lt0.1, Z/Zolt0.2, distancelt10 (dlt10 kpc)
CHECKED BY
4.105 eclipsing binaries of these 105
double-lined ones and at least 104 with
excellent solutions
BONUS distances for binaries to gt10 kpc
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Binarity and stellar evolution
Vlt17 stars with dlt10 kpc
Some 5.107 stars observed in exactly the same
way. Among them single stars and binaries with
orbital periods
from hours to hundreds of years.
How binarity influences stellar evolution?
GRAND PICTURE Altogether some 7.106 eclipsing
binaries discovered (Vlt20).
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GAIA Expected harvest
Vlt15 spectroscopy photometry of eclipsing
binaries Vlt15 spectroscopy of non-eclipsing
binaries Vlt19 photometry of eclipsing binaries
Together with astrometric and resolved binaries
with periods up to 106 years we get a complete
coverage of binarity phenomenon.
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Sredice galaksije oblet zvezde

• orbitalna perioda
• 15.2 let
• razdalja do pericentra
• 17 sv. ur
• sredicna masa
• (3.71.5)x106 Mo