2013A&A...560A..59C


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.16CEST19:34:10

2013A&A...560A..59C - Astronomy and Astrophysics, volume 560A, 59-59 (2013/12-1)

Density waves and star formation in grand-design spirals.

CEDRES B., CEPA J., BONGIOVANNI A., CASTANEDA H., SANCHEZ-PORTAL M. and TOMITA A.

Abstract (from CDS):

HII regions in the arms of spiral galaxies are indicators of recent star-forming processes. They may have been caused by the passage of the density wave or simply been created by other means near the arms. The study of these regions may give us clues to clarify the controversy about the existence of a triggering scenario, as proposed in the density-wave theory. If the passage of the density wave contributes significantly to the formation of HII regions in the arms of grand-design spirals, we can find a relationship in their position relative to the arms. Using Hα direct imaging, we characterize the HII regions from a sample of three grand-design galaxies: NGC 5457, NGC 628, and NGC 6946. Broad-band images in R and I were used to determine the position of the arms. The HII regions found to be associated with arms were selected for the study. The age and star formation rate of these HII regions was obtained using measurements on the Hα line. The distance between the current position of the selected HII regions and the position they would have if they had been created in the centre of the arm was calculated. A parameter, T, which measures whether a region was created in the arm or in the disc, was defined. With the help of the T parameter we determine that the majority of regions were formed some time after the passage of the density wave, and the regions are located behind the zone they should have occupied (in the direction of the rotation of the galaxy) had they been formed in the centre of the arm. Moreover, the relative efficiency of the star formation rate between arm and interarm was calculated for all the galaxies. The large number of regions created after the passage of the arm may be explained by the effect of the density wave, which helps to create the star-forming regions after its passage. There is clear evidence of triggering for NGC 5457 and a co-rotation radius is proposed. A more modest triggering seems to exist for NGC 628, and insignificant evidence of triggering is found for NGC 6946.

Abstract Copyright:

Journal keyword(s): galaxies: spiral - H II regions - galaxies: star formation - galaxies: star clusters: general - galaxies: structure

Simbad objects: 9

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Number of rows : 9

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 M 74 G 01 36 41.772 +15 47 00.46 10.52 10.00 9.46 9.16   ~ 1402 1
2 NGC 638 GiG 01 39 37.8434689430 +07 14 14.124561107   14.4       ~ 43 0
3 NGC 682 GiG 01 49 04.608 -14 58 29.57   13   12.41   ~ 26 0
4 NGC 2997 GiG 09 45 38.7537949543 -31 11 27.357027761   9.97 9.41 8.84 9.9 ~ 379 0
5 NGC 3922 GiG 11 51 13.4366861177 +50 09 24.750280716   13.8       ~ 42 0
6 M 100 AGN 12 22 54.9318850854 +15 49 20.294302163 10.04 10.05 9.35     ~ 1647 2
7 M 51 GiP 13 29 52.698 +47 11 42.93   9.26 8.36 8.40   ~ 3783 4
8 M 101 GiP 14 03 12.583 +54 20 55.50   8.46 7.86 7.76   ~ 2547 2
9 NGC 6946 H2G 20 34 52.332 +60 09 13.24   10.5       ~ 2235 2

    Equat.    Gal    SGal    Ecl

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2020.07.16-19:34:10

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