J/MNRAS/434/806     Pre-main-sequence isochrones. II. SFR       (Bell+, 2013)

Pre-main-sequence isochrones. II. Revising star and planet formation time-scales. Bell C.P.M., Naylor T., Mayne N.J., Jeffries R.D., Littlefair S.P. <Mon. Not. R. Astron. Soc., 434, 806-831 (2013)> =2013MNRAS.434..806B 2013MNRAS.434..806B
ADC_Keywords: Associations, stellar ; Stars, pre-main sequence ; Isochrones ; Photometry Keywords: techniques: photometric - stars: evolution - stars: formation - stars: fundamental parameters - Hertzsprung-Russell and colour-magnitude diagrams - stars: pre-main-sequence Abstract: We have derived ages for 13 young (<30Myr) star-forming regions and find that they are up to a factor of 2 older than the ages typically adopted in the literature. This result has wide-ranging implications, including that circumstellar discs survive longer (≃10-12Myr) and that the average Class I lifetime is greater (≃1Myr) than currently believed. For each star-forming region, we derived two ages from colour-magnitude diagrams. First, we fitted models of the evolution between the zero-age main sequence and terminal-age main sequence to derive a homogeneous set of main-sequence ages, distances and reddenings with statistically meaningful uncertainties. Our second age for each star-forming region was derived by fitting pre-main-sequence stars to new semi-empirical model isochrones. For the first time (for a set of clusters younger than 50Myr), we find broad agreement between these two ages, and since these are derived from two distinct mass regimes that rely on different aspects of stellar physics, it gives us confidence in the new age scale. This agreement is largely due to our adoption of empirical colour-Teff relations and bolometric corrections for pre-main-sequence stars cooler than 4000K. The revised ages for the star-forming regions in our sample are: ∼2Myr for NGC 6611 (Eagle Nebula; M 16), IC 5146 (Cocoon Nebula), NGC 6530 (Lagoon Nebula; M 8) and NGC 2244 (Rosette Nebula); ∼6Myr for σ Ori, Cep OB3b and IC 348; ∼10Myr for λ Ori (Collinder 69); ∼11Myr for NGC 2169; ∼12Myr for NGC 2362; ∼13Myr for NGC 7160; ∼14Myr for χPer (NGC 884); and ∼20Myr for NGC 1960 (M 36). Description: The observations presented were obtained using the 2.5m Isaac Newton Telescope (INT) on La Palma at the same time as our Pleiades observations described in Paper I (Bell et al., 2012MNRAS.424.3178B 2012MNRAS.424.3178B, Cat. J/MNRAS/424/3178). We refer the reader to Paper I for details of our observational techniques, photometric calibration and data reduction. 24-Jan-2024: This is an updated version of the catalogues correcting a bug whereby some stars within about 3 arcseconds of each other were merged into a single object in the final catalogue. Since the resulting object always had the position of the brighter star, this resulted in a star whose magnitude was too faint. The bug was fixed by using a smaller radius search to define which stars in different observations were likely to be the same star (1 arcsec vs 3 arcsec). File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 66 19 The central coordinates for each field of view and limiting magnitude in the INT-WFC (UgriZ)WFC bandpasses (for a signal-to-noise of 10) for our sample of SFRs table2.dat 113 26 *Photometric catalogues presented in this study refs.dat 111 39 References table9.dat 282 68665 Cep OB3b Full catalogue table10.dat 282 676 Cep OB3b Members catalogue table11.dat 282 51922 χ Per Full catalogue table12.dat 282 584 χ Per Members catalogue table13.dat 282 20111 IC 348 Full catalogue table14.dat 282 310 IC 348 Members catalogue table15.dat 282 65761 IC 5146 Full catalogue table16.dat 282 126 IC 5146 Members catalogue table17.dat 282 103739 λ Ori Full catalogue table18.dat 282 205 λ Ori Members catalogue table19.dat 282 41236 NGC 1960 Full catalogue table20.dat 282 54 NGC 1960 Members catalogue table21.dat 282 33654 NGC 2169 Full catalogue table22.dat 282 35 NGC 2169 Members catalogue table23.dat 282 37323 NGC 2244 Full catalogue table24.dat 282 522 NGC 2244 Members catalogue table25.dat 282 53259 NGC 2362 Full catalogue table26.dat 282 326 NGC 2362 Members catalogue table27.dat 282 57492 NGC 6530 Full catalogue table28.dat 282 663 NGC 6530 Members catalogue table29.dat 282 51073 NGC 6611 Full catalogue table30.dat 282 898 NGC 6611 Members catalogue table31.dat 282 59798 NGC 7160 Full catalogue table32.dat 282 90 NGC 7160 Members catalogue table33.dat 282 90001 σ Ori Full catalogue table34.dat 282 238 σ Ori Members catalogue -------------------------------------------------------------------------------- Note on table2.dat: The members catalogues use the data where stars variable from night to night have been replaced by the values from one night as described in Paper I (Bell et al., 2012, Cat. J/MNRAS/424/3178). -------------------------------------------------------------------------------- See also: J/MNRAS/424/3178 : PMS isochrones. Pleiades benchmark (Bell+, 2012) http://www.astro.ex.ac.uk/people/timn/Catalogues/ : The Cluster Collaboration Home Page Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 10 A10 --- SFR Cluster name 11- 12 A2 --- m_SFR Multiplicity index of central source 14- 15 I2 h RAh Right ascension (J2000.0) 17- 18 I2 min RAm Right ascension (J2000.0) 20- 23 F4.1 s RAs Right ascension (J2000.0) 25 A1 --- DE- Declination sign (J2000) 26- 27 I2 deg DEd Declination (J2000) 29- 30 I2 arcmin DEm Declination (J2000) 32- 35 F4.1 arcsec DEs Declination (J2000) 37- 40 F4.1 mag Ulim ?=- Limiting magnitude in U WFC bandpass 42- 45 F4.1 mag glim Limiting magnitude in g WFC bandpass 47- 50 F4.1 mag rlim Limiting magnitude in r WFC bandpass 52- 55 F4.1 mag ilim Limiting magnitude in i WFC bandpass 57- 60 F4.1 mag Zlim Limiting magnitude in Z WFC bandpass 62- 63 I2 --- Fld1 [7/90] Minimal Field number in table 9-34 65- 66 I2 --- Fld2 [7/93] Maximal Field number in table 9-34 -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 10 A10 --- SFR Cluster name 12- 13 I2 --- Tab Table number 15- 16 I2 --- Fld1 [7/90] Minimal Field number in table 9-34 18- 19 I2 --- Fld2 [7/93] Maximal Field number in table 9-34 21- 34 A14 --- Desc Description 37-113 A77 --- Source Sources (1) -------------------------------------------------------------------------------- Note (1): Sources used in the identification of pre-MS members in refs.dat file (see also Appendix A). -------------------------------------------------------------------------------- Byte-by-byte Description of file: refs.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 2 I2 --- Ref Reference number 4- 22 A19 --- BibCode BibCode 24- 51 A28 --- Aut Author's name 53-111 A59 --- Com Comments -------------------------------------------------------------------------------- Byte-by-byte Description of file (# headlines): table9.dat table??.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 3- 7 F5.2 --- Field [7.01/93.04] Field 11- 15 I5 --- ID [1/20799] Identification number 18- 19 I2 h RAh Right ascension (J2000.0) 21- 22 I2 min RAm Right ascension (J2000.0) 24- 29 F6.3 s RAs [0/60] Right ascension (J2000.0) 31 A1 --- DE- Declination sign (J2000) 32- 33 I2 deg DEd Declination (J2000) 35- 36 I2 arcmin DEm Declination (J2000) 38- 42 F5.2 arcsec DEs [0/60] Declination (J2000) 46- 53 F8.3 pix Xpos X position 57- 64 F8.3 pix Ypos Y position 69- 75 F7.3 mag gmag WFC g magnitude 80- 86 F7.3 mag e_gmag [-99/99] rms uncertainty on gmag (2) 89- 90 A2 --- f_gmag Flag on gmag, OO=OK (1) 93- 99 F7.3 mag g-i WFC g-i colour index 104-110 F7.3 mag e_g-i [-99/127] rms uncertainty on g-i (2) 113-114 A2 --- f_g-i Flag on g-i, OO=OK (1) 117-123 F7.3 mag U-g WFC U-g colour index 129-134 F6.3 mag e_U-g [-99/99] rms uncertainty on U-g (2) 137-138 A2 --- f_U-g Flag on U-g, OO=OK (1) 140-147 F8.3 mag r-i WFC r-i colour index 152-158 F7.3 mag e_r-i [-99/127] rms uncertainty on r-i (2) 161-162 A2 --- f_r-i Flag on r-i, OO=OK (1) 165-171 F7.3 mag i-Z WFC i-Z colour index 177-182 F6.3 mag e_i-Z [-99/99] rms uncertainty on i-Z (2) 185-186 A2 --- f_i-Z Flag on i-Z, OO=OK (1) 189-195 F7.3 mag Umag WFC U magnitude 200-206 F7.3 mag e_Umag [-99/99] rms uncertainty on Umag (2) 209-210 A2 --- f_Umag Flag on Umag, OO=OK (1) 213-219 F7.3 mag rmag WFC r magnitude 224-230 F7.3 mag e_rmag [-99/99] rms uncertainty on rmag (2) 233-234 A2 --- f_rmag Flag on rmag, OO=OK (1) 237-243 F7.3 mag imag WFC i magnitude 248-254 F7.3 mag e_imag [-99/99] rms uncertainty on imag (2) 257-258 A2 --- f_imag Flag on imag, OO=OK (1) 261-267 F7.3 mag Zmag WFC Z magnitude 272-278 F7.3 mag e_Zmag [-99/99] rms uncertainty on Zmag (2) 281-282 A2 --- f_Zmag Flag on Zmag, OO=OK (1) -------------------------------------------------------------------------------- Note (1): Quality flag (2 flags for a color index) as follows: O = O.K. (clean detection) A = Absent input data B = Background fit failed [unused] C = Large relative transparency correction (cloudy) [unused] E = Too close to CCD edge F = Flagged pixel I = Ill-determined background [unused] M = Negative (minus) counts N = Non-stellar P = Position fit failed [unused] R = Uncalibrated region S = Saturated V = Variable H = poor profile correction in the optimal photometry reduction L = a star has been identified with counts above the pixel linearity limit on the CCD during the pixel flagging procedure W = photometry taken at a random position to test for the effects of crowding in the field. Note (2): the error is negative when there are negative counts (flag M). -------------------------------------------------------------------------------- History: 24-Sep-2014: From electronic version of the journal 24-Jan-2024: tables updated References: Bell et al., Paper I 2012MNRAS.424.3178B 2012MNRAS.424.3178B, Cat. J/MNRAS/424/3178
(End) Patricia Vannier [CDS] 29-Jul-2014
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