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 use HST/ACS to study the resolved stellar populations of the nearby,nearly edge-on galaxy NGC4244 across its outer disk surface density break. Thestellar photometry allows us to study the distribution of different stellarpopulations and reach very low equivalent surface brightnesses. We find thatthe break occurs at the same radius for young, intermediate age, and old stars.The stellar density beyond the break drops sharply by a factor of at least 600in 5 kpc. The break occurs at the same radius independent of height above thedisk, but is sharpest in the midplane and nearly disappears at large heights.These results make it unlikely that truncations are caused by a star formationthreshold alone: the threshold would have to keep the same radial position fromless than 100 Myr to 10 Gyr ago, in spite of potential disturbances such asinfall and redistribution of gas by internal processes. A dynamicalinterpretation of truncation formation is more likely such as due to angularmomentum redistribution by bars or density waves, or heating and stripping ofstars caused by the bombardment of dark matter sub-halos. The latterexplanation is also in quantitative agreement with the small diffuse componentwe see around the galaxy.

Stellar populations across the NGC4244 truncated galactic disk