We present the first study of bars in the local Universe , based on the Sloan Digitized Sky Survey ( SDSS ) .
The large sample of \sim 5000 local galaxies provides the largest study to date of local bars and minimizes the effect of cosmic variance .
The sample galaxies have M _ { g } \leq - 18.5 mag and cover the redshift range 0.01 \leq z < 0.04 .
We use a color cut in the color-magnitude diagram and the Sérsic index n to identify disk galaxies .
We characterize bars and disks using r -band images and the method of iterative ellipse fits and quantitative criteria developed in Jogee at al .
( 2004 , ApJL , 615 , L105 ) .
After excluding highly inclined ( i > 60 ^ { \circ } ) systems our results are : ( 1 ) the optical ( r -band ) fraction of barred galaxies among local disk galaxies is 43 \% ( Figure 1 , left panel ) , which confirms the ubiquity of local bars , in agreement with other optical studies based on smaller samples ( e.g .
Eskridge et al .
2000 , AJ , 119 , 536 , Marinova & Jogee 2006 , astro-ph/0608039 ) ; ( 2 ) the optical bar fraction rises for bluer galaxies , suggesting a relation between bars and star formation ( Figure 1 , middle panel ) ; ( 3 ) preliminary analyzes suggest that the optical bar fraction increases steeply with the galaxy effective radius ( r _ { eff } , Figure 1 , right panel ) ; ( 4 ) the optical bar fraction at z \sim 0 is \sim 35 \% for bright disks ( M _ { g } \leq - 19.3 mag ) and strong ( bar ellipticity > 0.4 ) , large-scale ( bar semi-major axis > 1.5 kpc ) bars , which is comparable to the value of \sim 30 \pm 6 \% reported earlier ( Jogee et al .
2004 ) for similar disks and bars at z \sim 0.2 - 1.0 . 1 The optical bar fraction as a function of M _ { g } ( left panel ) , g - r color ( middle panel ) , and r _ { eff } ( right panel ) .
The number next to each point denotes the total number of galaxies in the corresponding bin .
The dashed line indicates the total optical bar fraction .
Only bins with more than 10 objects are shown . Figure 1 The optical bar fraction as a function of M _ { g } ( left panel ) , g - r color ( middle panel ) , and r _ { eff } ( right panel ) .
The number next to each point denotes the total number of galaxies in the corresponding bin .
The dashed line indicates the total optical bar fraction .
Only bins with more than 10 objects are shown .