Open AccessISO ‐LWS two‐colour diagram of young stellar objects
Author(s) -
Pezzuto S.,
Grillo F.,
Benedettini M.,
Caux E.,
Di Giorgio A. M.,
Giannini T.,
Leeks S. J.,
Lorenzetti D.,
Nisini B.,
Saraceno P.,
Spinoglio L.,
Tommasi E.
Publication year - 2002
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2002.05146.x
Subject(s) - physics , astrophysics , young stellar object , stars , photometry (optics) , astronomy , infrared excess , diagram , hertzsprung–russell diagram , confusion , stellar classification , t tauri star , observatory , stellar evolution , star formation , psychology , statistics , mathematics , psychoanalysis
We present a [60–100] versus [100–170]μm two‐colour diagram for a sample of 61 young stellar objects (YSOs) observed with the Long Wavelength Spectrometer (LWS) on‐board the Infrared Space Observatory ( ISO ). The sample consists of 17 Class 0 sources, 15 Class I, nine Bright Class I ( L bol >10 4 L ⊙ ) and 20 Class II (14 Herbig Ae/Be stars and six T Tauri stars). We find that each class occupies a well‐defined region in our diagram with colour temperatures increasing from Class 0 to Class II. Therefore the [60–100] versus [100–170] two‐colour diagram is a powerful and simple tool to derive from future (e.g. with the Herschel Space Observatory ) photometric surveys the evolutionary status of YSOs. The advantage over other tools already developed is that photometry at other wavelengths is not required: three flux measurements are enough to derive the evolutionary status of a source. As an example we use the colours of the YSO IRAS 18148−0440 to classify it as Class I. The main limitation of this work is the low spatial resolution of the LWS which, for some objects, causes a high uncertainty in the measured fluxes due to background emission or to source confusion inside the LWS beam.