Star Clusters in the M31 Galaxy Southwest Field. Photometric Survey and Population Properties ; Žvaigždžių spiečiai M31 galaktikos pietvakarinėje dalyje. Fotometrinė apžvalga ir populiacijos savybės

Sujets

• Galaxies
• M
• Physics
• Star cluster
• Star formation
• Stars
• List of Lithuanian gods

Informations

• Publié par: vilnius_university
• Publié le: 01 janvier 2010
• Nombre de lectures: 19
• Langue: English
• Poids de l'ouvrage: 11 Mo

Extrait

VILNIUS UNIVERSITY
Donatas Narbutis
St ar Clusters
in the M31 Galaxy Southwest Field.
Photometric Sur vey and Popula tion Pr oper ties
Do ctoral Dissertation
Ph ysical scien ces, Ph ysics (02 P)
Vilnius, 2010Do ctoral Dissertation w as completed during 2006–2010 at Vilnius
Univ ersit y .
Scien tific sup ervisor:
Dr. Vladas V ansevičius (Vilnius Univ ersit y , Institute of Ph ysics of Cen ter
for Ph ysical Sciences and T ec hnology , Ph ysical sciences, Ph ysics – 02 P)VILNIA US UNIVERSITET AS
Donatas Narbutis
Žv aigždžių spiečiai
M31 galaktik os pietv akarinėje d al yje.
F otometrinė apžv alga ir populia cijos sa vybės
Daktaro disertacija
Fiziniai mokslai, fizika (02 P)
Vilnius, 2010Disertacija rengta 2006–2010 metais Vilniaus univ ersitete.
Mokslinis v ado v as:
Dr. Vladas V ansevičius (Vilniaus univ ersitetas, Fizinių ir tec hnologijos
mokslų cen tro Fizik os institutas, fiziniai mokslai, fizika – 02 P)Abstract
Observ ational evidence that star formation pro ceeds in a clustered manner
raises a question on the mass function of star clusters and their ev olution.
Ho w ev er, w e ha v e a limited scop e of these pro cesses in the Milky W a y
galaxy . The M31 galaxy is the nearest stellar system similar to our Galaxy ,
therefore, it is the most suitable one to pro vide clues for understanding the
star cluster p opulation and the ev olution of galactic structures. Ho w ev er,
detailed study of stellar p opulations and star clusters is a c hallenging task
for ground-based observ ations due to cro wded stellar fields.
Using Subaru telescop e Suprime-Cam wide-field images, a surv ey of clus-
ters w as carried out in the disk region of the M31 galaxy south w est field,
whic h is a close analogue to that of the Solar neigh b orho o d in terms of
c hemical comp osition, stellar densit y , and quiescen t star formation. Data
analysis metho ds and programs w ere dev elop ed, tested, and applied for
cro wded wide-field image reduction and ev olutionary parameter determina-
tion of semi-resolv ed star clusters.
The main results are: (1) enhanced star cluster formation activit y in
M31 o ccurred ∼ 70 Myr ago; (2) appro ximately 10% of stars b orn in star
clusters remain there at 100 Myr age; (3) the c haracteristic lifetime of a
4cluster of∼10 M mass is∼ 300 Myr; (4) the mass function of star clusters
⊙
in M31 is similar to that in other lo w star formation activit y galaxies, and
it is b est describ ed b y the Sc hec h ter’s function with a c haracteristic mass of
5
∼2×10 M ; (5) a ric h in termediate-mass cluster p opulation in M31, whic h
⊙
app ears to b e scarce or hidden b y dust clouds in the Milky W a y galaxy , w as
disco v ered.
56A c kno wledgmen ts
I w ould lik e to express gratitude to Rima Stonkutė, A udrius Bridžius,
Dmitrij Semiono v, Viktoras Dev eikis, Ram ūnas V anagas, Iev a Šablevičiūtė,
T adas Mineikis, V aldas V ansevičius, Mark Kidger, F abiola Martin-Luis,
Nobuo Arimoto, and Keiic hi K o daira.
I appreciate n umerous in teractions and help from J. Sūdžius, S. Bar-
tašiūtė, J. Sp erauskas, A. Kučinskas, V. Straižys, G. T rinkūnas, S. Nar-
but ytė, S. Ka v aliauskas, T. Lunec kas, M. Karčiauskas, J. Bagdonaitė, V.
Dobro v olskas, A. Iv anauskas, S. Bek eraitė, A. Pučinskas, S. Raudeliū-
nas, R. Lazauskaitė, G. T autv aišienė, K. Černis, S. Lo v čikas, G. V aliauga,
G. Kakaras, R. Beinorienė, O. Gaubienė, A. Viso c kienė, P . Jablonka, T.
Hasega w a, Y. K omiy ama, S. Miy azaki, C. Ikuta, K. Oh ta, N. T am ura, and
Y. Y amada among man y p eople.
I w ould lik e to ac kno wledge Vilnius Univ ersit y , Institute of Ph ysics, and
State Studies F oundation for financial supp ort pro viding opp ortunities to
participate in summer/win ter sc ho ols and conferences, and exc hange ideas
with other groups w orking on the same sub ject.
I am v ery grateful to sup ervisor Vladas V ansevičius and indebted to m y
paren ts and family .
78Con ten ts
Abstract 5
A c kno wledgmen ts 7
Con ten ts 10
In tro duction 11
Motiv ation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Aims of the study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Main tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Results and statemen ts to defend . . . . . . . . . . . . . . . . . . . . . 13
P ersonal con tribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Publications on thesis topic in refereed journals . . . . . . . . . . . . . 14
Other publications in refereed journals . . . . . . . . . . . . . . . . . . 15
Presen tations at conferences . . . . . . . . . . . . . . . . . . . . . . . . 16
Thesis outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1 Star Cluster Sample 19
1.1 Observ ations and Data . . . . . . . . . . . . . . . . . . . . . . . . 23
1.1.1 Suprime-Cam Images . . . . . . . . . . . . . . . . . . . . . 23
1.1.2 LGGS Images . . . . . . . . . . . . . . . . . . . . . . . . . 24
1.1.3 HST Images . . . . . . . . . . . . . . . . . . . . . . . . . . 25
1.1.4 Multi-Band Maps . . . . . . . . . . . . . . . . . . . . . . . 26
1.2 Star Cluster Surv ey . . . . . . . . . . . . . . . . . . . . . . . . . . 29
1.2.1 Sample Selection . . . . . . . . . . . . . . . . . . . . . . . 29
1.2.2 Photometry . . . . . . . . . . . . . . . . . . . . . . . . . . 31
1.2.3 Ap erture Size Effects . . . . . . . . . . . . . . . . . . . . . 33
1.2.4 Catalog . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
2 Analysis Metho ds and Soft w are 45
2.1 Wide-Field Mosaic Image Reductions . . . . . . . . . . . . . . . . 45
2.1.1 Corrections of CCD Image Defects . . . . . . . . . . . . . 45
2.1.2 Co ordinate System . . . . . . . . . . . . . . . . . . . . . . 51
2.1.3 Global Photometric Solution . . . . . . . . . . . . . . . . 53
2.1.4 Image Stac king . . . . . . . . . . . . . . . . . . . . . . . . 54
2.1.5 PSF homogenization . . . . . . . . . . . . . . . . . . . . . 55
2.1.6 Photometric Standards . . . . . . . . . . . . . . . . . . . . 56
2.1.7 Calibrations . . . . . . . . . . . . . . . . . . 61
2.2 Determination of Structural P arameters . . . . . . . . . . . . . . 62
92.2.1 FitClust Algorithm . . . . . . . . . . . . . . . . . . . . 63
2.2.2 Analytical Mo dels . . . . . . . . . . . . . . . . . . . . . . 64
2.2.3 Mo del P arameter Space . . . . . . . . . . . . . . . . . . . 65
2.2.4 Iden tification of Con taminan ts . . . . . . . . . . . . . . . 66
2.2.5 Determination of Half-Ligh t Radii . . . . . . . . . . . . . 67
2.3 Photometric Quan tification . . . . . . . . . . . . . . . . . . . . . 67
2.3.1 P arameter Degeneracy Constrains . . . . . . . . . . . . . . 69
2.3.2 Cluster P arameters F rom UBVRI . . . . . . . . . . . . . . 70
2.3.3 P F rom UBVRIJHK . . . . . . . . . . . 75
3 Prop erties of Star Cluster P opulation 87
3.1 P arameter Determination . . . . . . . . . . . . . . . . . . . . . . 87
3.1.1 Structural Prop erties . . . . . . . . . . . . . . . . . . . . . 89
3.1.2 Ev olutionary Prop erties . . . . . . . . . . . . . . . . . . . 92
3.2 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . 94
3.2.1 Half-Ligh t Radius . . . . . . . . . . . . . . . . . . . . . . 94
3.2.2 Age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
3.2.3 Mass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
3.2.4 Extinction . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
3.2.5 Metallicit y . . . . . . . . . . . . . . . . . . . . . . . . . . 103
3.2.6 Spatial Distribution . . . . . . . . . . . . . . . . . . . . . 105
3.2.7 Ob jects for Detailed Study . . . . . . . . . . . . . . . . . . 107
3.2.8 Cluster F ormation and Disruption . . . . . . . . . . . . . 110
Conclusions 115
References 116
10