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

Recent studies have identified several young stellar objects (YSOs) whichexhibit significant mid-infrared (mid-IR) variability. A wide range of physicalmechanisms may be responsible for these variations, including changes in aYSO's accretion rate or in the extinction or emission from the inner disk. Wehave obtained and analyzed multi-epoch near-infrared (NIR) spectra for fiveactively accreting YSOs in the $\rho$ Oph star-forming region along withcontemporaneous mid-IR light curves obtained as part of the YSOVAR Spitzer/IRACsurvey. Four of the five YSOs exhibit mid-IR light curves with modest ($\sim0.2$--0.4 mag) but statistically significant variations over our 40-dayobservation window. Measuring the strengths of prominent photosphericabsorption lines and accretion sensitive \ion{H}{1} and \ion{He}{1} lines ineach NIR spectrum, we derive estimates of each YSO's spectral type, effectivetemperature ({\Teff}), and $H$ band extinction ($A_H$), and analyze the timeevolution of their NIR veiling ($r_H$ and $r_K$) and mass accretion rates({\Macc}). Defining a YSO's evolutionary stage such that heavily veiled, highaccretion rate objects are less evolved than those with lower levels of veilingand ongoing accretion, we infer that GY 314 is the most evolved YSO in oursample, with GY 308 and GY 292 at progressively earlier evolutionary stages.Leveraging our multi-epoch, multi-wavelength dataset, we detect significantvariations in mass accretion rates over timescales of days to weeks, but findthat extinction levels in these YSOs remain relatively constant. We find nocorrelation between these YSO mid-IR light curves and time-resolved veiling ormass accretion rates, such that we are unable to link their mid-IR variabilitywith physical processes localized near the inner edge of the circumstellar diskor within regions which are directly responsive to mass accretion...

Potential Drivers of Mid-Infrared Variability in Young Stars: testing physical models with multi-epoch near-infrared spectra of YSOs in {\rho} Oph