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J/ApJ/786/117      M31 PHAT star clusters ages and masses     (Fouesneau+, 2014)

The panchromatic Hubble Andromeda treasury. V. Ages and masses of the year 1 stellar clusters. Fouesneau M., Johnson L.C., Weisz D.R., Dalcanton J.J., Bell E.F., Bianchi L., Caldwell N., Gouliermis D.A., Guhathakurta P., Kalirai J., Larsen S.S., Rix H.-W., Seth A.C., Skillman E.D., Williams B.F. <Astrophys. J., 786, 117 (2014)> =2014ApJ...786..117F (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Clusters, globular ; Extinction ; Stars, ages ; Stars, masses Keywords: galaxies: individual: M31 - galaxies: star clusters: general - methods: data analysis - techniques: photometric Abstract: We present ages and masses for 601 star clusters in M31 from the analysis of the six filter integrated light measurements from near-ultraviolet to near-infrared wavelengths, made as part of the Panchromatic Hubble Andromeda Treasury (PHAT). We derive the ages and masses using a probabilistic technique, which accounts for the effects of stochastic sampling of the stellar initial mass function. Tests on synthetic data show that this method, in conjunction with the exquisite sensitivity of the PHAT observations and their broad wavelength baseline, provides robust age and mass recovery for clusters ranging from ∼102 to 2x106 M. We find that the cluster age distribution is consistent with being uniform over the past 100 Myr, which suggests a weak effect of cluster disruption within M31. The age distribution of older (>100 Myr) clusters falls toward old ages, consistent with a power-law decline of index -1, likely from a combination of fading and disruption of the clusters. We find that the mass distribution of the whole sample can be well described by a single power law with a spectral index of -1.9±0.1 over the range of 103-3x105 M. However, if we subdivide the sample by galactocentric radius, we find that the age distributions remain unchanged. However, the mass spectral index varies significantly, showing best-fit values between -2.2 and -1.8, with the shallower slope in the highest star formation intensity regions. We explore the robustness of our study to potential systematics and conclude that the cluster mass function may vary with respect to environment. Description: For this paper, we use the list of 601 high-probability cluster candidates from the Johnson et al. (2012, J/ApJ/752/95) Year 1 catalog, which contains integrated photometry through six broadband filters from the UV to the near-infrared: F275W (UV), F336W (U), F475W (g), F814W (I), F110W (J), F160W (H). Clusters were detected by eye, primarily based on the F475W images, and visually classified based on their sizes, shapes, and concentrations as explained in Johnson et al. (2012, J/ApJ/752/95). Objects: ----------------------------------------------------- RA (ICRS) DE Designation(s) ----------------------------------------------------- 00 42 44.33 +41 16 07.5 M31 = NAME Andromeda ----------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 138 601 Ag-Mass and extinction results from the analysis with discrete cluster models
See also: J/A+A/449/143 : Photometry of M31 globular cluster candidates (Ma+, 2006) J/AJ/139/1438 : SED and age estimates of 104 M31 globular clusters (Wang+, 2010) J/ApJ/752/95 : PHAT stellar cluster survey. I. Year 1 (Johnson+, 2012) J/A+A/549/A60 : Ages and [Fe/H] of M31 globular clusters (Cezario+, 2013) J/ApJ/762/123 : PHAT. IV. Initial Mass Function (Weisz+, 2013) J/ApJS/215/9 : PHAT X. UV-IR photometry of M31 stars (Williams+, 2014) J/ApJ/827/33 : PHAT. XVI. Star cluster masses and ages (Johnson+, 2016) J/A+A/602/A112 : M31 PHAT star clusters (de Meulenaer+, 2017) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 4 I4 --- PCID [1/1728] PHAT identifier ([JSD2012] PC NNNN in Simbad) (1) 6- 23 F18.15 deg RAdeg Right Ascension in decimal degrees (J2000) 25- 42 F18.15 deg DEdeg Declination in decimal degrees (J2000) 44- 46 F3.1 mag AV-best ? Best V band extinction (2) 49- 51 F3.1 mag AV-p16 ? The 16th percentile V band extinction 54- 56 F3.1 mag AV-p84 ? The 84th percentile V band extinction 59- 61 F3.1 mag AV-p2.5 ? The 2.5th percentile V band extinction 64- 66 F3.1 mag AV-p97.5 ? The 97.5th percentile V band extinction 68- 73 F6.3 [yr] logA-best ? Best log age (2) 75- 80 F6.3 [yr] logA-p16 ? The 16th percentile log age 82- 87 F6.3 [yr] logA-p84 ? The 84th percentile log age 89- 94 F6.3 [yr] logA-p2.5 ? The 2.5th percentile log age 96-101 F6.3 [yr] logA-p97.5 ? The 97.5th percentile log age 104-108 F5.3 [Msun] logM-bset ? Best log mass (2) 111-115 F5.3 [Msun] logM-p16 ? The 16th percentile mass 118-122 F5.3 [Msun] logM-p84 ? The 84th percentile mass 125-129 F5.3 [Msun] logM-p2.5 ? The 2.5th percentile mass 132-136 F5.3 [Msun] logM-p97.5 ? The 97.5th percentile mass 138 I1 --- CFlag [0/1]? Suspicious fit from visual color-magnitude inspection (3)
Note (1): As in Johnson et al. (2012, J/ApJ/752/95). Note (2): Represents the triplet which maximize the full posterior. Note (3): Flag as follows: 0 = no; 1 = yes.
History: From electronic version of the journal References: Dalcanton et al. PHAT Suvey 2012ApJS..200...18D Rosenfield et al. Paper I 2012ApJ...755..131R Williams et al. Paper II 2012ApJ...759...46W Beerman et al. Paper III 2012ApJ...760..104B Weisz et al. Paper IV 2013ApJ...762..123W Cat. J/ApJ/762/123 Fouesneau et al. Paper V 2014ApJ...786..117F Simones et al. Paper VI 2014ApJ...788...12S Dong et al. Paper VII 2014ApJ...785..136D Dalcanton et al. Paper VIII 2015ApJ...814....3D Veyette et al. Paper IX 2014ApJ...792..121V Williams et al. Paper X 2014ApJS..215....9W Cat. J/ApJS/215/9 Lewis et al. Paper XI 2015ApJ...805..183L Gregersen et al. Paper XII 2015AJ....150..189G Wagner-Kaiser et al. Paper XIII 2015MNRAS.451..724W Cat. J/MNRAS/451/724 Senchyna et al. Paper XIV 2015ApJ...813...31S Gordon et al. Paper XV 2016ApJ...826..104G Johnson et al. Paper XVI 2016ApJ...827...33J Cat. J/ApJ/827/33 Lewis et al. Paper XVII 2017ApJ...834...70L Johnson et al. Paper XVIII 2017ApJ...839...78J
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 21-Jul-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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