English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We investigate colors and mass-to-light ratios ($M/L$s) of the bulges anddisks for 28 nearby spiral galaxies with various morphological types of Sab toScd, using images in optical and near-infrared ($V$, $I$, and $J$) bands andpublished rotation curves. It is shown that the observed colors and $M/L$sgenerally agree with the galaxy formation model with an exponentially decliningstar formation rate and shallow slope (ex. Scalo) initial mass function (IMF)for both the bulges and the disks. We find that the bulge $M/L$ is generallyhigher than the disk $M/L$ and that the galaxies with larger bulge-to-totalluminosity ratio tend to have a smaller bulge $M/L$. The fact indicates thatthe luminosity-weighted average age of bulges for early-type spirals is youngerthan that of later-type spirals. These results support a formation scenariothat produces young stars for the bulges of middle-type and early-type spirals.

Colors and Mass-to-Light Ratios of Bulges and Disks of Nearby Spiral Galaxies