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UC Santa Cruz UC Santa Cruz Electronic Theses and Dissertations UC Santa Cruz UC Santa Cruz Electronic Theses and Dissertations Title AGB Stars in the Disk, Satellites, and Halo of M31 Permalink https://escholarship.org/uc/item/39k1w2rq Author Hamren, Katherine Publication Date 2016 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California UNIVERSITY OF CALIFORNIA SANTA CRUZ AGB STARS IN THE DISK, SATELLITES, AND HALO OF M31 A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in ASTRONOMY & ASTROPHYSICS by Katherine M. Hamren June 2016 The Dissertation of Katherine M. Hamren is approved: Professor Puragra GuhaThakurta, Chair Professor Constance Rockosi Professor Graeme Smith Dean Tyrus Miller Vice Provost and Dean of Graduate Studies Copyright c by Katherine M. Hamren 2016 Table of Contents List of Figures vi List of Tables viii Abstract x Dedication xi Acknowledgments xii 1 Introduction1 1.1 The physics of AGB stars.............................1 1.2 Observations of AGB Stars in the Local Group.................4 1.3 Outstanding Questions..............................6 1.4 Why M31?....................................7 1.5 Chapter Descriptions...............................9 1.5.1 The C/M ratio in the disk of M31....................9 1.5.2 Carbon stars in the satellites and halo of M31.............. 10 1.5.3 M-giants in the satellites and halo of M31................ 11 2 The C/M Ratio in the Disk of M31 12 2.1 Introduction.................................... 12 2.2 Data........................................ 14 2.2.1 Photometry................................ 14 2.2.2 Spectroscopy............................... 15 2.2.3 Spectroscopic Templates......................... 16 2.2.4 AGB Identification............................ 17 2.2.5 Carbon Star Identification........................ 19 2.3 Defining M.................................... 33 2.3.1 Boyer et al. 2013............................. 34 2.3.2 Brewer et al. 1995............................ 34 2.3.3 Battinelli & Demers 2005........................ 36 iii 2.4 C/M ratio across M31............................... 40 2.4.1 As a function of galactocentric radius.................. 40 2.4.2 As a function of metallicity........................ 43 2.4.3 As a function of SFH........................... 49 2.5 Discussion..................................... 52 2.5.1 The C/M ratio vs. environment...................... 52 2.5.2 Possible effects of dust.......................... 56 2.5.3 Comparing definitions of M....................... 58 2.6 Conclusion.................................... 59 3 Carbon stars in the Satellites and Halo of M31 61 3.1 Introduction.................................... 61 3.2 Data........................................ 64 3.2.1 Spectroscopic and Photometric Observations.............. 69 3.2.2 Synthetic Photometry and Photometric Transformations........ 72 3.2.3 Membership............................... 73 3.3 The Carbon Star Sample............................. 75 3.3.1 Identification............................... 75 3.3.2 Selection Functions............................ 83 3.4 Photometric properties.............................. 90 3.5 Spectroscopic Properties............................. 96 3.6 Discussion..................................... 106 3.6.1 General properties of the SPLASH carbon stars............. 106 3.6.2 Characterizing the faint carbon stars................... 109 3.6.3 Carbon star luminosity by environment................. 111 3.7 Conclusions.................................... 116 4 M-giants in the Satellites and Halo of M31 117 4.1 Introduction.................................... 117 4.2 Data........................................ 120 4.2.1 Spectroscopic and Photometric Observations.............. 120 4.2.2 Membership............................... 121 4.3 The M-giant sample................................ 122 4.3.1 Automated M-star classification..................... 123 4.3.2 Separating the AGB and RGB...................... 131 4.4 Spatial distribution of M31 M-giants....................... 132 4.5 Physical Properties of M31 M-giants....................... 138 4.5.1 Effective Temperature.......................... 138 4.5.2 Stellar Dust and Variability........................ 143 4.5.3 Metallicity................................ 150 4.5.4 The AGB versus the RGB........................ 155 4.6 Summary and Conclusions............................ 162 iv 5 Conclusions and Future Directions 164 5.1 Future directions: M31AGES........................... 166 5.1.1 Motivation................................ 166 5.1.2 Survey progress and next steps...................... 168 v List of Figures 1.1 Post-main sequence HR diagram.........................3 2.1 Distribution of spectral types represented in MW template spectra....... 16 2.2 PHAT color-color diagrams and sample spectra................. 18 2.3 Evaluation of the K-statistic based carbon star identification method...... 20 2.4 Comparison of MW template carbon stars and SPLASH carbon stars...... 21 2.5 FBPS color-color diagram with disk carbon stars................ 22 2.6 Brewer et al. 1995 based selection of M-stars.................. 35 2.7 Battinelli & Demers 2005 based selection of M-stars.............. 37 2.8 Spectroscopic selection of M-stars........................ 39 2.9 Distribution of AGB stars in the disk of M31................... 41 2.10 Log(C/M) in radial bins.............................. 42 2.11 Positions of HII regions and PNe in the disk of M31.............. 44 2.12 Log(C/M) vs various properties of the M31 disk................. 46 2.13 Figure 2.12, continued.............................. 47 2.14 Age proxy as a function of radius in the disk of M31.............. 51 3.1 SPLASH Survey Map............................... 65 3.2 Positions of carbon stars identified in M31 satellites............... 76 3.3 Figure 3.2, continued............................... 77 3.4 Distribution of C-star magnitudes with respect to the TRGB.......... 91 3.5 Distribution of V - I and CN-TiO........................ 93 3.6 Color-color diagrams............................... 94 3.7 PCA-reconstructed C-star spectra......................... 97 3.8 First five C-star eigenspectra........................... 100 3.9 C-star Eigencoefficient correlations........................ 101 3.10 EC2 vs EC4 .................................... 103 3.11 ECs of bright vs faint carbon stars........................ 105 3.12 Fraction of faint carbon stars by environment.................. 112 4.1 Sample M-giant with regions of interest marked................. 123 4.2 SPLASH M31 members in S-index space.................... 126 vi 4.3 Sample features for M and non-M-type stars in the training set......... 128 4.4 Sample M-giant spectra.............................. 130 4.5 Map of M-giants in their host satellites...................... 133 4.6 Figure 4.5, continued............................... 134 4.7 M-giant M-types and their associated effective temperatures.......... 140 4.8 Model derived Teff ................................. 142 4.9 M-giant CN–TiO versus V - I color-color diagram................ 145 4.10 DUSTiNGS CMDs of optical-MIR matches................... 147 4.11 M-giant 3.6-4.5 versus V - I color-color diagram................. 149 4.12 ΣCa distributions for AGB versus RGB stars.................. 151 4.13 CaT-based metallicity of M-giants........................ 153 4.14 Mean ΣCa as a function of AGB contamination fraction............ 154 4.15 Effect of smoothing and S/N cuts on PCA.................... 157 4.16 M-giant eigenspectra............................... 158 4.17 Distribution of eigencoefficients of the second M-giant eigenspectrum..... 161 5.1 M31AGES Survey Map.............................. 169 5.2 M31AGES NIR photometry overlaid with SPLASH carbon stars........ 171 vii List of Tables 2.1 Positions and Magnitudes of Carbon Stars in the M31 Disk........... 24 2.1 Positions and Magnitudes of Carbon Stars in the M31 Disk........... 25 2.1 Positions and Magnitudes of Carbon Stars in the M31 Disk........... 26 2.1 Positions and Magnitudes of Carbon Stars in the M31 Disk........... 27 2.1 Positions and Magnitudes of Carbon Stars in the M31 Disk........... 28 2.1 Positions and Magnitudes of Carbon Stars in the M31 Disk........... 29 2.1 Positions and Magnitudes of Carbon Stars in the M31 Disk........... 30 2.1 Positions and Magnitudes of Carbon Stars in the M31 Disk........... 31 2.1 Positions and Magnitudes of Carbon Stars in the M31 Disk........... 32 2.2 Coefficients of Multiple Regression Models................... 53 3.1 Properties of M31 Satellites Observed by SPLASH............... 66 3.1 Properties of M31 Satellites Observed by SPLASH............... 67 3.1 Properties of M31 Satellites Observed by SPLASH............... 68 3.2 Carbon stars in the satellites and halo of M31.................. 78 3.2 Carbon stars in the satellites and halo of M31.................. 79 3.2 Carbon stars in the satellites and halo of M31.................. 80 3.2 Carbon stars in the satellites and halo of M31.................. 81 3.3 Selection Function Data.............................. 86 3.3 Selection Function Data.............................. 87 3.3 Selection Function Data.............................. 88 3.3 Selection Function Data.............................. 89 3.3 Selection Function Data.............................. 90 3.4 Carbon stars in the DUSTiNGS sample..................... 95 3.5 Fraction of faint carbon stars in the Local Group................. 108 3.5 Fraction of faint carbon stars
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