On the metallicity gradient of the Galactic disk Export

@article{citeulike:4890364, abstract = {Aims: The iron abundance gradient in the Galactic stellar disk provides fundamental constraints on the chemical evolution of this important Galaxy component. However the spread around the mean slope is, at fixed Galactocentric distance, larger than estimated uncertainties. Methods: To provide quantitative constraints on these trends we adopted iron abundances for 265 classical Cepheids (more than 50\% of the currently known sample) based either on high-resolution spectra or on photometric metallicity indices. Homogeneous distances were estimated using near-infrared Period-Luminosity relations. The sample covers the four disk quadrants and their Galactocentric distances range from \~{}5 to \~{}17 kpc. Results: A linear regression over the entire sample provides an iron gradient of -0.051+/-0.004 dex/kpc. The above slope agrees quite well, within the errors, with previous estimates based either on Cepheids or on open clusters covering similar Galactocentric distances. However, once we split the sample in inner (Rg \< 8 kpc) and outer disk Cepheids we found that the slope (-0.130+/-0.015 dex/kpc) in the former region is \~{}3 times steeper than the slope in the latter one (-0.042+/-0.004 dex/kpc). We found that in the outer disk the radial distribution of metal-poor (MP, [Fe/H]\<-0.02 dex) and metal-rich (MR) Cepheids across the four disk quadrants does not show a clear trend when moving from the innermost to the external disk regions. We also found that the relative fractions of MP and MR Cepheids in the 1st and in the 3rd quadrant differ at 8 sigma (MP) and 15 sigma (MR) level.}, archivePrefix = {arXiv}, author = {Pedicelli, S. and Bono, G. and Lemasle, B. and Francois, P. and Groenewegen, M. and Lub, J. and Pel, J. W. and Laney, D. and Piersimoni, A. and Romaniello, M. and Buonanno, R. and Caputo, F. and Cassisi, S. and Castelli, F. and Leurini, S. and Pietrinferni, A. and Primas, F. and Pritchard, J.}, citeulike-article-id = {4890364}, citeulike-linkout-0 = {http://arxiv.org/abs/0906.3140}, citeulike-linkout-1 = {http://arxiv.org/pdf/0906.3140}, day = {17}, eprint = {0906.3140}, keywords = {abundance\_gradients, milky\_way, thin\_disk}, month = {Jun}, posted-at = {2009-07-16 14:24:32}, priority = {2}, title = {On the metallicity gradient of the Galactic disk}, url = {http://arxiv.org/abs/0906.3140}, year = {2009} }

TY - JOUR ID - citeulike:4890364 L3 - citeulike-article-id:4890364 N2 - Aims: The iron abundance gradient in the Galactic stellar disk provides fundamental constraints on the chemical evolution of this important Galaxy component. However the spread around the mean slope is, at fixed Galactocentric distance, larger than estimated uncertainties. Methods: To provide quantitative constraints on these trends we adopted iron abundances for 265 classical Cepheids (more than 50% of the currently known sample) based either on high-resolution spectra or on photometric metallicity indices. Homogeneous distances were estimated using near-infrared Period-Luminosity relations. The sample covers the four disk quadrants and their Galactocentric distances range from ~5 to ~17 kpc. Results: A linear regression over the entire sample provides an iron gradient of -0.051+/-0.004 dex/kpc. The above slope agrees quite well, within the errors, with previous estimates based either on Cepheids or on open clusters covering similar Galactocentric distances. However, once we split the sample in inner (Rg < 8 kpc) and outer disk Cepheids we found that the slope (-0.130+/-0.015 dex/kpc) in the former region is ~3 times steeper than the slope in the latter one (-0.042+/-0.004 dex/kpc). We found that in the outer disk the radial distribution of metal-poor (MP, [Fe/H]<-0.02 dex) and metal-rich (MR) Cepheids across the four disk quadrants does not show a clear trend when moving from the innermost to the external disk regions. We also found that the relative fractions of MP and MR Cepheids in the 1st and in the 3rd quadrant differ at 8 sigma (MP) and 15 sigma (MR) level. TI - On the metallicity gradient of the Galactic disk KW - abundance_gradients KW - milky_way KW - thin_disk AU - Pedicelli, S AU - Bono, G AU - Lemasle, B AU - Francois, P AU - Groenewegen, M AU - Lub, J AU - Pel, JW AU - Laney, D AU - Piersimoni, A AU - Romaniello, M AU - Buonanno, R AU - Caputo, F AU - Cassisi, S AU - Castelli, F AU - Leurini, S AU - Pietrinferni, A AU - Primas, F AU - Pritchard, J PY - 2009/Jun/17/ UR - http://arxiv.org/abs/0906.3140 ER -