Universita’ degli Studi di Padova Facoltà di Scienze MM.FF.NN. Dipartimento di Astronomia Scuola di Dottorato in Astronomia ARCS:THEASIAGOREDCLUMP SPECTROSCOPICSURVEYANDITS FIRSTAPPLICATIONS Ph. D. Thesis of: Supervisor: Marica Valentini Prof. Ulisse Munari Marica Valentini: ARCS: the Asiago Red Clump Spectroscopic Survey and its first applications, Ph. D. Thesis, © December 2009 To my family... CONTENTS 1 red clump stars 1 1.1 Introduction1 1.2 The Red Clump2 1.3 Structure and evolution of Red Clump stars2 1.3.1 The Fine Structure9 1.4 Properties 11 1.5 The Red Clump in Hipparcos 11 1.6 Red Clump Stars as Standard Candles: the calibra- tion of MRedClump 14 1.7 Red Clump stars as Milky Way structure indica- tors 19 1.8 The Red Clump as Star Formation History Trac- ers 22 1.9 Catalogs of Red Clump in literature 23 1.9.1 This thesis and the ARCS survey 24 2 target selection and assembling of the imput catalogue 27 2.1 ARCS Selection Criteria 27 2.2 The Problem of contamination 30 2.2.1 Binaries 30 2.2.2 AGB 31 2.3 Comparison of ARCS with other catalogs in litera- ture 31 3 data acquisition and reduction 35 3.1 Instrument and performances 35 3.1.1 Spectrograph characteristics 35 3.2 Modus operandi at the telescope 36 3.3 Data Reduction 36 3.3.1 Data Modeling with IRAF 36 3.3.2 Scattered Light Evaluation and Correction 38 4 radial velocity and atmospheric parame- ter determination 45 4.1 Introduction 45 4.2 The synthetic library 45 4.3 Cross Correlation on syntetic Spectra 48 4.4 χ2 test 49 4.4.1 The χ2 method 49 vii viii Contents 5 testing the method 51 5.1 Introduction 51 5.2 Tests on radial velocity measurements 52 5.2.1 IAU Velocity Standards 52 5.2.2 RAVE 52 5.3 Test on atmospheric parameters :Soubiran, Hekker, Takeda catalogs 54 5.3.1 The importance of the S/N 55 5.4 Test on atmospheric parameters: stars from litera- ture 55 5.5 Test on atmospheric parameters: Open Clusters 65 5.6 Discussion 65 6 constructing arcs high resolution cata- log 69 6.1 Introduction 69 6.2 Distances 69 6.2.1 Hipparcos distances 70 6.2.2 K-band 71 6.2.3 Spectrophotometric distances 71 6.3 Galactic Velocities 71 6.4 Reddening 75 6.5 Detected binaries 75 7 arcs output catalogue 83 7.1 Introduction 83 7.2 The Catalog 83 8 applications of arcs results on galactic structure and kinematics 95 8.1 Introduction 95 8.2 The Milky Way Disk 96 8.3 Moving Groups 96 8.4 Thin Disk 99 8.5 ARCS space velocities and orbits 99 8.5.1 Distances and space velocities 99 8.5.2 Galactic model of mass distribution and or- bits integration 102 8.6 ARCS Ages 102 8.6.1 Comparison of ARCS gravities with PARAM gravities 104 8.7 Age distribution of ARCS objects 104 8.7.1 Age-Velocity relation - don’t know if feasi- ble 104 8.7.2 Age-Metallicity relation -to check 106 8.7.3 Vertical metallicity gradient- to check 106 Contents ix 8.7.4 A signature of Radial Mixing?(provvisory ti- tle) 106 8.8 Structures in the U-V velocity space of ARCS ob- jects 107 8.8.1 Moving Groups 107 8.8.2 Kinematic branches 107 8.9 Conclusions 107 Bibliography 127 LISTOFFIGURES Figure 1 Hertzsprung-Russell (MV , B-V) diagrams for the 4902 and 16631 stars from the Hipparcos Catalog.3 Figure 2 The evolution of the internal structure of a star of 1.3 M 4 Figure 3 Evolutionary tracks on Hertzsprung-Russel Diagram6 Figure 4 Position of the ZAHB for stellar evolution- ary tracks of different masses and metallic- ity.7 Figure 5 The evolution of the internal structure of a star of 1.3 M during the He flash.8 Figure 6 Distribution of clump stars in the MV vs B − V diagram, from theoretical models and from Hipparcos data. 10 Figure 7 Udalski calibration of MI vs V − I color and metallicity. 15 Figure 8 Groenewegen (2008) calibration of MI vs V − I color and metallicity. 17 Figure 9 Groenewegen (2008) calibration of MK vs V − K color and metallicity. 18 Figure 10 Subtracted map in terms of surface density in the sky for RC stars in order to detect Canis Major 21 Figure 11 Spectral type distribution if ARCS objects 28 Figure 12 Aitoff equatorial projection of ARCS targets. 28 Figure 13 Aitoff galactic projection of ARCS targets. 29 Figure 14 Distribution in magnitude of ARCS, Famaey, Takeda, Soubiran and Hekker targets. 33 Figure 15 Echelle Orders 31-35 of ARCS 203222. 37 Figure 16 Echelle orders 36-40 dof ARCS 203222. 38 Figure 17 Echelle orders 41-45 of ARCS 203222. 39 Figure 18 Echelle orders 46-51 of ARCS 203222. 40 Figure 19 Echelle orders 52-57 of star ARCS 203222 . 41 Figure 20 Scattered light. 43 Figure 21 Comparison between radial velocities present in Raave DR2 and atmospheric parameters derived by our cross-correlation method. 54 xi xii List of Figures Figure 22 Differences between atmospheric parameters obtained with rogue ARCS χ2 technique and literature values. 60 Figure 23 Differences between atmospheric parameters obtained with ARCS χ2 technique with the correction and literature values. 61 Figure 24 Comparison between atmospheric parame- ters present in literature and atmospheric patameters derived by our χ2. 62 Figure 25 Comparison between atmospheric parame- ters present in literature and atmospheric patameters derived by our χ2. 63 Figure 26 Comparison between distances from Hippar- cos 1997 parallaxes and distances from the 2007 Revised Hipparcos parallaxes. 70 Figure 27 Distances from Hipparcos New Reduction of Raw Data (2007) catalog plotted against photometric distance from K-2MASS. 72 Figure 28 Mean MV as function of the spectral type, from Keenan & Barnbaum (1999). 73 Figure 29 Distances from Hipparcos New Reduction of Raw Data (2007) catalog plotted against photometric distance from V Keenan & Barn- baum calibrations. 73 Figure 30 Distances from Hipparcos New Reduction of Raw Data (2007) catalog plotted against photometric distance from V Keenan & Barn- baum calibrations. 74 Figure 31 Comparison between distances obtained with revised Hipparcos parallaxes (Van Leeuwen , 2007) and those derived from V calibration of Red Clump (Keenan & Barnbaum, 2000) and V magnitudes. 76 Figure 32 ARCS’s V absolute magnitude vs [M/H] for the 46 ARCS targets which parallax has σπ π ≤ 15% (from revised Hipparcos parallaxes, van Leeuwen, 2007). From top to bottom: MV vs Teff , M V vs logg and MV vs [M/H]. There is no relevant dependence of MV from [M/H]. 77 List of Figures xiii Figure 33 V and K absolute magnitude vs [M/H] for the 46 ARCS targets which parallax has σπ π ≤ 15% (from revised Hipparcos parallaxes, van Leeuwen, 2007). Top panel: MK vs [M/H]. Dashed line is the dependence of MK on [M/H] of Alves (2000): MKRC 0.57 ± 0.36F e/H 0.25 −1.64 ± 0.07. Dotted line is the mean MK for the Red Clump found by Groenewe- gen (2008), MKRC = -1.54. Bottom panel: MV vs [M/H]. There is no relevant depen- dence of MV from [M/H]. 78 Figure 34 Histogram differences in radial velocities. 80 Figure 35 Histograms of distribution of the U,V,W ve- locities of ARCS objects. 100 Figure 36 Distribution in the U,V,W velocity space of ARCS objects. 101 Figure 38 UV distribution of the 300 ARCS objects. 104 Figure 37 Distribution in age of the ARCS stars with a meaningful age computed by PARAM. 105 Figure 39 UV distribution of the 300 ARCS objects. 106 LISTOFTABLES Table 1 Atmospheric parameters of RC stars present in literature. 12 Table 2 Distances of Milky Way bulge,LMC, SMC, M31, Fornax and Carina as obtained using Red Clump stars method. 16 Table 3 Wavelenght intervals covered by Echelle Or- ders. 42 Table 4 Range of atmospheric parameters explored by the adopted synthetic spectral library. 47 Table 5 Comparison between literature velocities and velocity measured with the ARCS’s method of cross-correlation for 7 IAU standard ve- locity stars. All the values are in km s−1 52 Table 6 Comparison between velocities given by RAVE DR2 (Zwitter et al., 2008) and velocity mea- sured with the ARCS’s method of cross-correlation for stars. All the values are in km s−1 53 Table 7 Average and errors of the difference between the values of the atmospheric parameters of the 34 stars present in literature catalogs and the ones obtained with the χ2 method for Echelle orders from 38 (5830-5966 Å) to 46 (4815-4922 Å). 56 Table 8 Comparison between the atmospheric param- eters obtained with ARCS’s χ2 method and values present in Soubiran catalog (Soubi- ran et al. 2005) for 14 stars. Soubiran’s objects were observed with the same set-up and S/N of ARCS sample, and atmospheric parameters were derived by using the same method and synthetic grid as ARCS. 57 Table 9 Comparison between the atmospheric param- eters obtained with ARCS’s χ2 method and values present in Hekker catalog (Hekker & Mendelez, 1997 ) for 11 stars. Hekkers’s objects were observed with the same set-up and S/N of ARCS sample, and atmospheric parameters were derived by using the same method and synthetic grid as ARCS. 58 xv xvi List of Tables Table 10 Comparison between the atmospheric param- eters obtained with ARCS’s χ2 method and values present in Takeda catalog (Takeda et al., 2008 ) for 10 stars.