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J/MNRAS/429/1981    NGC 2264 T Tauri star properties         (Barentsen+, 2013)

Bayesian inference of T Tauri star properties using multi-wavelength survey photometry. Barentsen G., Vink J.S., Drew J.E., Sale S.E. <Mon. Not. R. Astron. Soc., 429, 1981-2000 (2013)> =2013MNRAS.429.1981B (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Stars, pre-main sequence ; Photometry, infrared Keywords: accretion, accretion discs - methods: data analysis - surveys - stars: pre-main-sequence - open clusters and associations: individual: NGC 2264 Abstract: There are many pertinent open issues in the area of star and planet formation. Large statistical samples of young stars across star-forming regions are needed to trigger a breakthrough in our understanding, but most optical studies are based on a wide variety of spectrographs and analysis methods, which introduces large biases. Here we show how graphical Bayesian networks can be employed to construct a hierarchical probabilistic model which allows pre-main-sequence ages, masses, accretion rates and extinctions to be estimated using two widely available photometric survey data bases (Isaac Newton Telescope Photometric Hα Survey r'/Hα/i' and Two Micron All Sky Survey J-band magnitudes). Because our approach does not rely on spectroscopy, it can easily be applied to homogeneously study the large number of clusters for which Gaia will yield membership lists. We explain how the analysis is carried out using the Markov chain Monte Carlo method and provide python source code. We then demonstrate its use on 587 known low-mass members of the star-forming region NGC 2264 (Cone Nebula), arriving at a median age of 3.0Myr, an accretion fraction of 20±2 per cent and a median accretion rate of 10-8.4M☉/yr. The Bayesian analysis formulated in this work delivers results which are in agreement with spectroscopic studies already in the literature, but achieves this with great efficiency by depending only on photometry. It is a significant step forward from previous photometric studies because the probabilistic approach ensures that nuisance parameters, such as extinction and distance, are fully included in the analysis with a clear picture on any degeneracies. Description: We showed how the theory of graphical Bayesian networks can be used to define a probabilistic model which allows extinction, age, mass and accretion rate to be inferred from IPHAS r'/Hα/i' and 2MASS J-band photometry without the need for spectroscopy. We applied the method to 587 low-mass members of the NGC 2264 star-forming region File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table3.dat 92 587 IPHAS and 2MASS photometry for known members of NGC 2264 which satisfy our selection and quality criteria table4.dat 73 587 *Posterior expectation values and standard deviations for parameters of NGC 2264 members
Note on table4.dat: obtained from IPHAS and 2MASS photometry using Bayesian inference.
See also: II/321 : IPHAS DR2 Source Catalogue (Barentsen+, 2014) J/AJ/135/441 : VRIHα photometry in NGC 2264 (Sung+, 2008) Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 6 A6 --- Sung Object identifier (CNNNNN) as defined by Sung et al. (2008, Cat. J/AJ/135/441) (G1) 8- 26 A19 --- IPHAS IPHAS name (JHHMMSS.ss+DDMMSS.s) 28- 32 F5.2 mag rmag IPHAS r magnitude 34- 37 F4.2 mag e_rmag rms uncertainty on rmag 39- 43 F5.2 mag Hamag IPHAS Hα magnitude 45- 48 F4.2 mag e_Hamag rms uncertainty on Hamag 50- 54 F5.2 mag imag IPHAS i magnitude 56- 59 F4.2 mag e_imag rms uncertainty on imag 61- 65 F5.2 mag Jmag 2MASS J magnitude 67- 70 F4.2 mag e_Jmag rms uncertainty on Jmag 72- 76 F5.2 mag Hmag 2MASS H magnitude 77 A1 --- u_Hmag Uncertainty flag on Hmag 78- 81 F4.2 mag e_Hmag ? rms uncertainty on Hmag 83- 87 F5.2 mag Kmag 2MASS K magnitude 88 A1 --- u_Kmag Uncertainty flag on Kmag 89- 92 F4.2 mag e_Kmag ? rms uncertainty on Kmag
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 6 A6 --- Sung Object identifier (CNNNNN) as defined by Sung et al. (2008, Cat. J/AJ/135/441) (G1) 8- 12 F5.2 [mag] logA0 Extinction parameter 14- 17 F4.2 [mag] e_logA0 rms uncertainty on logA0 19- 23 F5.2 [Msun] logMass Stellar mass 25- 28 F4.2 [Msun] e_logMass rms uncertainty on logMass 30- 33 F4.2 [yr] logAge Stellar age 35- 38 F4.2 [yr] e_logAge rms uncertainty on logAge 40- 44 F5.2 [0.1nm] logEWHa Hα emission equivalent width 46- 49 F4.2 [0.1nm] e_logEWHa rms uncertainty on logEWHa 51- 54 F4.1 [Lsun] logLHa Excess Hα luminosity 56- 58 F3.1 [Lsun] e_logLHa rms uncertainty on logLHa 60- 64 F5.1 [Msun/yr] logdMacc/dt ? Accretion rate 66- 68 F3.1 [Msun/yr] e_logdMacc/dt ? rms uncertainty on logdMacc/dt 70- 73 A4 --- Com Comments
Global notes: Note (G1): Cl* NGC 2264 CID CNNNNN in Simbad
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 14-Jun-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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