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 present a 3x3 degrees, 105-pointing, high-resolution neutral hydrogen (HI)mosaic of the M81 galaxy triplet (including the galaxies M81, M82 and NGC 3077,as well as dwarf galaxy NGC 2976) obtained with the Very Large Array (VLA) Cand D arrays. This uniformly covers the entire area and velocity range of thetriplet with a resolution of ~20'' or ~420 pc. The data reveal many small-scaleanomalous velocity features highlighting the complexity of the interacting M81triplet. We compare our data with Green Bank Telescope (GBT) observations ofthe same area. This provides evidence for a substantial reservoir of low-columndensity gas in the northern part of the triplet, probably associated with M82.Such a reservoir is not found in the southern part. We report a number ofkpc-sized low-mass HI clouds with HI masses of a few times 10^6 Msun. Theirdynamical masses are much larger than their baryonic masses, which couldindicate the presence of dark matter if the clouds are rotationally supported.However, due to their spatial and kinematical association with HI tidalfeatures, it is more likely that the velocity widths indicate tidal effects orstreaming motions. We do not find any clouds not associated with tidal featuresdown to an HI mass limit of a few times 10^4 Msun. We compare the HI columndensities with resolved stellar density maps and find a star formationthreshold around 3-6 10^20 cm-2$. We find that extreme velocity dispersions canbe explained by a superposition of multiple components along the line of sightnear M81 as well as winds or outflows around M82. The velocity dispersionsfound are high enough that these processes could explain the linewidths ofDamped-Lyman-alpha absorbers observed at high redshift.

A high-resolution mosaic of the neutral hydrogen in the M81 triplet