PROTOSTARS

A photometric and spectral survey of young stars in nearby star-forming regions: towards a revised evolutionary sequence based on quantitative accretion/ejection diagnostics

 Partecipanti

Mappa

 Word cloud

Esplora la "nuvola delle parole (Word Cloud) per avere un'idea di massima del progetto.

 Obiettivo del progetto (Objective)

'This research project proposes to obtain the first unbiased survey on a large flux-limited sample of young stellar objects (YSOs) in 6 different molecular clouds. This study makes use of a huge dataset, namely various photometric maps from 0.6 μm up to 850 μm (including data from the Spitzer and the Herschel Space Telescope), and spectra (between 0.6 and 2.4 μm) of several YSOs in these clouds. The immediate aim of this proposal is to catalogue all the YSOs in the selected star forming regions, getting quantitative information on their accretion and ejection activity. In particular, line luminosities and ratios will be obtained from spectra to measure the fraction of source luminosity due to accretion, and the mass accretion and ejection rates in the late YSOs (Class I, II and III). Spectral energy distributions (SEDs) will be constructed from the photometric data to classify the objects, and to estimate the accretion luminosity and the mass accretion rate for early YSOs (Class 0). Mass ejection rates will be inferred from the YSO outflows. The final goal is then to redefine the YSO evolutionary classification, traditionally based on the SED alone, by means of diagnostic emission lines and the mass accretion rates. This will also allow us to derive the YSO lifetime in the various stages. Additionally, the proposed survey will provide the largest available catalogue of SEDs and spectra from YSOs, which will be fundamental for the selection of promising targets to be observed by highly oversubscribed instrumentation, such as the forthcoming James Webb Space Telescope.'

Introduzione (Teaser)

Scientists rely on spectral data to characterise a number of properties of astrophysical objects including their elemental compositions, densities and motion. EU-funded researchers composed and analysed a comprehensive data set of spectral characteristics of young forming stars highlighting the best parameters to accurately classify evolutionary stages.

Descrizione progetto (Article)

Spectral energy distributions (SEDs) describing the energy objects that radiate over the entire electromagnetic spectrum have conventionally been the main way of classifying the age and evolutionary phase of young stellar objects (YSOs).

YSOs attain most of their mass when an isolated rotating dense core collapses and forms an accreting protostellar core and disc that accumulates surrounding interstellar gas and dust via large gravitational forces.

Recent theoretical studies suggest that SED information alone is not sufficient to accurately determine whether YSOs are early (Class 0) or late (Classes I, II and III) phase. Rather, a combination of SED and near-infrared (NIR) spectroscopy that enables characterisation of the accreting protostar are required.

Given the lack of a comprehensive examination of both SED and NIR data from YSOs, European researchers initiated the Protostars project to create the first unbiased survey of a huge data set of selected Class I and Class II YSOs from six star-forming regions.

Scientists combined spectrographic data from the New Technology Telescope of the European Southern Observatory (ESO) and the Spitzer Space Telescope (SST) enabling construction of the YSOs SEDs and inference of main stellar parameters including accretion and ejection rates, spectral types and luminosities.

Results demonstrated that YSO emission lines indicative of accretion or outflow were better indicators of age than SEDs and provide the basis for selection of future observational targets.