Monitoring accretion rate variability in the Orion Nebula Cluster with the Wendelstein Wide Field Imager

Abstract

Context. The understanding of the accretion process has a central role in the understanding of star and planet formation. Aims. We aim to test how accretion variability influences previous correlation analyses of the relation between X-ray activity and accretion rates, which is important for understanding the evolution of circumstellar disks and disk photoevaporation. Methods. We monitored accreting stars in the Orion Nebula Cluster from November 24, 2014, until February 17, 2019, for 42 epochs with the Wendelstein Wide Field Imager in the Sloan Digital Sky Survey u g r filters on the 2 m Fraunhofer Telescope on Mount Wendelstein. Mass accretion rates were determined from the measured ultraviolet excess. The influence of the mass accretion rate variability on the relation between X-ray luminosities and mass accretion rates was analyzed statistically. Results. We find a typical interquartile range of ∼ 0.3 dex for the mass accretion rate variability on timescales from weeks to ∼ 2 years. The variability has likely no significant influence on a correlation analysis of the X-ray luminosity and the mass accretion rate observed at different times when the sample size is large enough. Conclusions. The observed anticorrelation between the X-ray luminosity and the mass accretion rate predicted by models of photoevaporation-starved accretion is likely not due to a bias introduced by different observing times.

Variability of Young Stellar Objects in the Perseus Molecular Cloud

“…The CMD slope angles due to accretion variation is around 62 • , in consistence with the bursters in our sample (middle left panel of Figure 14). We also compared the variability amplitudes in g-band with the accretion model (middle right panel of Figure 14), and the comparison indicates that the bursters in our sample have changes of L acc /L å in the range 0.1-0.3, these values are larger than the typical value of 0.11 in Flaischlen et al (2022), but within 1σ range of that work.…”

“…Burster variables are thought to arise from discrete accretion shocks. We model the CMD pattern for a star with T eff = 4000 K, and adopt the accretion spectrum from Manara et al (2013) with the same model parameters as in Flaischlen et al (2022), i.e., the electron temperature T slab = 11,000 K, the electron density n e = 10 15 cm −3 , and the optical depth at 300 nm τ 300 = 5.0. The CMD slope angles due to accretion variation is around 62 • , in consistence with the bursters in our sample (middle left panel of Figure 14).…”

HST Survey of the Orion Nebula Cluster in the H2O 1.4 μm Absorption Band. III. The Population of Substellar Binary Companions

“…(Alcalá et al 2014(Alcalá et al , 2017Manara et al 2016bManara et al , 2017aHartmann et al 2016). Recent works, however, show that accretion variability alone is not enough to explain the spread observed in Ṁacc measurements (Fischer et al 2022;Flaischlen et al 2022) that must therefore be also related to physical processes such as disk evolution. Is still not yet clear in what measure the Ṁacc ∝ M 2 * relation is due to the disk evolutionary process or if it reflects how the initial conditions scale with stellar mass (Manara et al 2022, and references therein).…”

Rubin Observatory LSST Stars Milky Way and Local Volume Star Clusters Roadmap

“…While typical changes in the young star-inner disk environment are triggered on comparable or shorter timescales (days to weeks) than the expected observing cadence for LSST fields (e.g., Costigan et al 2014;Flaischlen et al 2022), the long observational baseline over which young open clusters and star-forming regions will be regularly sampled will be The distances to some well-known star-forming regions are marked on the diagrams as a reference for the scale. These projections were derived by assuming the single-image and coadded-image 5σ depths simulated for the baseline survey (Bianco et al 2022), and converting them to expected limiting distances by using the MIST isochrones (Choi et al 2016;Dotter 2016) with synthetic LSST photometry, and a sample range of ages and extinction values.…”