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

Based on the near infrared spectra of 42 M dwarfs, carbon abundances aredetermined from the ro-vibrational lines of CO 2-0 band. We use Teff valuesbased on the angular diameters if available or apply a logTeff - M3.4 (theabsolute magnitude at 3.4 micron based on the WISE W1 flux and the Hipparcosparallax) relation to estimate Teff values of objects for which angulardiameters are unknown. Also, we discuss briefly the HR diagram of low massstars. On the observed spectrum of M dwarf, the continuum is depressed by thenumerous weak lines of H2O and only the depressed continuum or the pseudo-continuum can be seen. On the theoretical spectrum of M dwarfs, we find thatthe pseudo-continuum can be evaluated accurately thanks to the recent H2O linedatabase. Then quantitative analysis of the spectrum of M dwarf can be done byreferring to the pseudo-continua both on the observed and theoretical spectra.Since the basic principle of the spectroscopic analysis should be the samewhether the true- or pseudo-continuum is referred to, the difficulty related tothe continuum in cool stars can in principle be overcome. Then, the numerous COlines can be excellent abundance indicators of carbon, since almost all thecarbon atoms are in stable CO molecules whose abundance remains almostunchanged for the changes of physical condition in the photosphere and,somewhat unexpectedly, carbon abundances in late-type stars can best bedetermined in M dwarfs rather than in solar type stars. The resulting C/Feratios for most M dwarfs are nearly constant at about the solar value based onthe classical high carbon abundance rather than on the recently revised lowervalue. This result implies that the solar carbon abundance is atypical for itsmetallicity among the stellar objects in the solar neighborhood if the downwardrevised solar carbon abundance is correct.

Near Infrared Spectroscopy of M Dwarfs. I. CO Molecule as an Abundance Indicator of Carbon