DOCSLIB.ORG

The Universe After Gaia Data Release 2

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Universe After Gaia Data Release 2 The Universe after Gaia Data Release 2 Eugene Vasiliev Institute of Astronomy, Cambridge University of Z¨urich 4 October 2019 The Universe after Gaia Data Release 2 Eugene Vasiliev Institute of Astronomy, Cambridge University of Z¨urich 4 October 2019 Alberto Giacometti, \Le Nez" Synopsis Overview of the Gaia mission and DR2: scientific instruments, catalogue contents, measurement uncertainties, caveats and limitations. Scientific highlights: Kinematic complexity of the disk Accretion history of the halo Search for new objects (streams, satellites) Internal kinematics of stellar structures Measurement of Milky Way gravitational potential Astrometry 101 Position on the sky α; δ Parallax $ = 1=distance Proper motion µα; µδ Line-of-sight velocity vlos Binary orbit parameters How Gaia astrometry works Overview of Gaia mission G I Scanning the entire sky every couple of weeks BP RP RVS I Astrometry for sources down to 21 mag I Broad-band photometry/low-res spectra I Line-of-sight velocity down to 15 mag (end-of-mission) ∼ [Source: ESA] Overview of Data Release 2 astrometry I Based on 22 months of data collection 9 I Total number of sources: 1:69 10 RV × I Sources with full astrometry (parallax $, 9 proper motions µα∗; µδ): 1:33 10 × 9 I Colours (GBP ; GRP ): 1:38 10 × I Line-of-sight velocities: 7:2 106 colours × 6 108 I Effective temperature: 160 10 Teff ICRF3 prototype 107 vrad SSO × Variable Gaia DR1 6 Gaia-CRF2 Gaia DR2 n 6 Stellar parameters (R ; L ): 77 10 i 10 b I g × a 105 m 6 1 . Extinction and reddening: 88 10 0 4 I 10 r e p × 6 r 103 e Variable sources: 0:55 10 b I m 2 u 10 × N 101 100 5 10 15 20 25 Mean G [mag] [Brown+ 2018] Measurement uncertainties 10 parallax uncertainty [mas] 5 ] s a m 2 [ Parallax: 0 05 0 1 mas ) $ : : $ & ¾ ( 1 − x a l l Proper motion: 0 1 0 2 mas/yr a 0:5 µ : : r & a p − n i 0:2 y Line-of-sight velocity: 0 5 km/s t V : n & i a t r 0:1 e c n u 0:05 d r a d n a 0 02 t : RV measurements only for stars with S systematic error 0:01 Teff [3500 6900] K and GRVS 12 (G 13) . 0:005 2 ÷ ≤ 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 ] 10 1 G magnitude ¡ r radial velocity uncertainty [km/s] y proper motion uncertainty [mas/yr] 5 s a m [ ) x a 2 m ; m p ¾ 1 ( : m : 0:5 p n i e s p 0:2 i l l e r o 0:1 r r e f o 0:05 s i x a systematic error r o j 0:02 a m ¡ i 0:01 systematic error m e 1 mas/yr = 4:7 km/s × (D=1 Kpc) S 0:005 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 [Katz+ 2018] G magnitude [Lindegren+ 2018] Gaia parallaxes and the absolute distance scale Mean parallax of 5 × 105 quasars [Arenou+2018] 0:10 ¡63 0:08 ¡64 0:06 Compilation of parallax offset measurements [Lindegren+2018b] ¡65 0:04 1.15 ¡66 ] H = s 0 a m ¡67 0:02 [ 1.10 80.5 x 95% a l l ¡68 a 0 r 99% a 1.05 76.9 p ¡69 n a ¡0:02 i d e Declination [deg] 1.00 ¡70 73.2 M ¡0:04 Median parallax[mas] ¡71 0.95 69.5 68% ¡0:06 95% Planck16+RCDM ¡72 rescale local distance 0.90 65.9 99% ¡0:08 ¡73 Red Giants 0.85 ¡0:10 100 95 90 85 80 75 70 65 60 -0.02 0.00 0.02 0.04 0.06 0.08 0.10 Right Ascension [deg] parallax zeropoint (mas) Mean parallax of LMC stars [Lindegren+2018a] Cepheid distances and Planck constant [Riess+2018] The \golden" 6D sample 6 106 stars brighter than G 13 ∼ × ∼ 5 106 with parallax uncertainty $=$ 0:2 ≤ 4 106 3 106 2 106 Number of stars 106 0 0 2 4 6 8 10 Distance [kpc] [Babusiaux+ 2018; Katz+ 2018] Kinematic complexity in the disk I Moving groups in velocity space [Gaia Collaboration: Katz+2018] = more clearly seen in action space.) I Bar pattern speed constraints [Monari+2018] I Perturbations from spiral arms [Trick+2018] [Quillen+2018; Hunt+2018] I Tests of spiral structure theories [Sellwood+2018] [Quillen+2018] [Monari+2018] [Sellwood+2018] Vertical perturbations and the disk seismology Phase-space spiral [Antoja+2018] 10 perturbation from a (2 10) 10 M satellite − × crossing the disk 200 400 Myr ago (Sgr dSph?) − [Laporte+ 2018] [Darling & Widrow 2018] [Binney & Sch¨onrich2018] [Bland-Hawthorn+ 2018] [Li & Shen 2019] Radially-anisotropic population in the stellar halo 9 Evidence for a major merger with a 10 M satellite 8 10 Gyr ago & ∼ − Dispersion Anisotropy Rotation 200 1.0 80 (kinematics1<|z|<3 + metallicity) 3<|z|<5 [see also Kruijssen+20185<|z|<9 for globular clusters] 0.8 150 60 0.6 > e ` m 100 40 <V 0.4 50 mr 20 0.2 me mq 0 0.0 0 -3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -3.5 -3.0 -2.5 -2.0 -1.5 -1.0 [Fe/H] [Fe/H] [Fe/H] [Belokurov+ 2018 { SDSS+Gaia DR1] [Mackereth+ 2019 { APOGEE+Gaia DR2] [Helmi+ 2018 { APOGEE+Gaia DR2] [Fattahi+ 2018 { Gaia DR2] Radially-anisotropic population in the stellar halo 9 Evidence for a major merger with a 10 M satellite 8 10 Gyr ago & ∼ − (kinematics + metallicity) [see also Kruijssen+2018 for globular clusters] [Mackereth+ 2019 { APOGEE+Gaia DR2] Gaia{Enceladus Helmi+ 2018 [Fattahi+ 2018 { Gaia DR2] Radially-anisotropic population in the stellar halo 9 Evidence for a major merger with a 10 M satellite 8 10 Gyr ago & ∼ − Gaia{Enceladus Helmi+ 2018 Belokurov+ 2018 Finding substructures with Gaia 90 ◦ 90 ◦ north south 15 ◦ -15 ◦ 135 45 45 135 ◦ 30 ◦ ◦ ◦ -30 ◦ ◦ 3 45 ◦ -45 ◦ 10 60 ◦ -60 ◦ 75 ◦ -75 ◦ 180 ◦ 90 ◦ 0 ◦ -90 ◦ 180 ◦ Sagittarius stream 102 SMC # of sources per square degree 225 ◦ 315 ◦ 315 ◦ LMC 225 ◦ 101 270 ◦ 270 ◦ Stars with $ < 0:3, 1 < GBP GRP < 1:5, µα < 3:5, µδ < 3:5 (mainly distant halo) − j j j j Finding streams with Gaia Finding streams with Gaia Finding streams with Gaia Finding streams with Gaia GD-1 stream [Grillmair & Dionatos 2006] Finding new streams with Gaia 20 20 Phlegethon stream [Ibata+2018] 15 15 10 10 25 5 5 best fit orbital model ] ] c c p 0 p 0 k 30 k [ [ ] z y 1 30 5 5 ] r y g 10 10 e s d a [ 15 15 m b 35 [ 20 20 20 15 10 5 0 5 10 15 20 0 5 10 15 20 60 x [kpc] R [kpc] proper motion selection 40 15 10 Padova 10Gyr, [Fe/H] = 1.4 best fit orbital model 10 Phlegethon 10 ] 30 1 ] 5 1 r y 0 r ] 12 s 0 y g a e s m [ d 5 a [ ] m b g 10 10 [ a 14 b m 6015 [ 15 0 proper motion selection G 16 20 20 60 30 0 30 ] 1 25 [deg] r y s 30 a 18 m [ 35 40 20 45 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 3 (GBP GRP)0 [mag] 2 1 ] s a 0 m [ 1 2 3 400 ] 1 200 s m 0 k [ o i l e h 200 v 400 60 40 20 0 20 [deg] A census of stellar streams in the Milky Way Stream name Ylgr Sylgr Fj¨orm Fimbulthul Phlegethon Styx Kwando [Ibata+2019] Murrumbidgee Chenab Indus Jhelum Nix Aliqa Uma Willka Yaku Turranburra Orinoco Wambelong GD-1 [C.Mateu, GalStream database] A census of stellar streams in the Milky Way Stream name Ylgr Sylgr Fj¨orm Fimbulthul Phlegethon Styx Kwando Nix [Ibata+2019] Murrumbidgee Chenab Indus Jhelum Nix Aliqa Uma Willka Yaku Turranburra Orinoco Wambelong GD-1 Styx [C.Mateu, GalStream database] Finding new satellite galaxies with Gaia: Antlia 2 Stellar Density CMD Proper Motions 15 8 5 16 6 17 yr) 4 / 400 (deg) 0 18 2 (mas (mag) δ 0 δ 300 r ∆ All Stars 19 0 s) pm / 200 20 2 − -5 21 4 100 -5 0 5 0.5 0.0 0.5 1.0 1.5 − 5 0 − − HRV(km ∆α cos (δ) (deg) (g r)0(mag) pm α cos (δ) (mas/yr) 15 − 8 0 5 16 6 100 − 3 2 1 0 1.0 0.5 0.0 0.5 1.0 1.5 1.0 0.5 0.0 0.5 1.0 1.5 17 yr) 4 − − − − − − − / [Fe/H](dex) µα cos δ(mas/yr) µδ(mas/yr) (deg) 0 18 2 (mas LMC δ (mag) 0 δ LMC r ∆ 17.5 17.5 19 0 − − Selected Stars pm 15.0 15.0 20 2 − − − Fornax Sgr dsph Fornax -5 Sgr dsph 12.5 12.5 21 4 − − -5 0 5 0.5 0.0 0.5 1.0 1.5 − 5 0 − − AndXIX ∆α cos (δ) (deg) (g r)0(mag) pm α cos (δ) (mas/yr) 10.0 LeoII 10.0 LeoII AndXIX Draco − − Draco − Sextans 15 40 Sextans 20.56 0.1 ± Cra 2 Ant 2 5 (mag) 7.5 Cra 2 Ant 2 (mag) 7.5 16 V − V − M M 17 30 5.0 5.0 − − 18 2.5 2.5 − − =1 19 20 (deg) 0 M/L (mag) δ MW galaxies 0 r Classical dwarfs ∆ 0.0 0.0 20 M31 galaxies LG galaxies = 100 = 1000 21 10 = 31 = 32 MW GCs 2.5 µ µ 2.5 M/L M/L 0 1 2 3 4 3 4 5 6 7 8 9 22 10 10 10 10 10 10 10 10 10 10 10 10 -5 rh(pc) M(r<rh)(M ) 23 0 ⊙ 0.4 0.2 0.0 19.0 19.5 20.0 20.5 21.0 -5 0 5 − − The most diffuse galaxy [Torrealba+2018] (g r)0(mag) DMBHB ∆α cos (δ) (deg) − Determination of cluster membership CMD sky plane proper motion space Determination of cluster membership Probabilistic membership determination A hard cutoff in PM space is not always possible and is conceptually unsatisfactory.
Load more

Recommended publications
  • Spatial Distribution of Galactic Globular Clusters: Distance Uncertainties and Dynamical Effects
    Juliana Crestani Ribeiro de Souza Spatial Distribution of Galactic Globular Clusters: Distance Uncertainties and Dynamical Effects Porto Alegre 2017 Juliana Crestani Ribeiro de Souza Spatial Distribution of Galactic Globular Clusters: Distance Uncertainties and Dynamical Effects Dissertação elaborada sob orientação do Prof. Dr. Eduardo Luis Damiani Bica, co- orientação do Prof. Dr. Charles José Bon- ato e apresentada ao Instituto de Física da Universidade Federal do Rio Grande do Sul em preenchimento do requisito par- cial para obtenção do título de Mestre em Física. Porto Alegre 2017 Acknowledgements To my parents, who supported me and made this possible, in a time and place where being in a university was just a distant dream. To my dearest friends Elisabeth, Robert, Augusto, and Natália - who so many times helped me go from "I give up" to "I’ll try once more". To my cats Kira, Fen, and Demi - who lazily join me in bed at the end of the day, and make everything worthwhile. "But, first of all, it will be necessary to explain what is our idea of a cluster of stars, and by what means we have obtained it. For an instance, I shall take the phenomenon which presents itself in many clusters: It is that of a number of lucid spots, of equal lustre, scattered over a circular space, in such a manner as to appear gradually more compressed towards the middle; and which compression, in the clusters to which I allude, is generally carried so far, as, by imperceptible degrees, to end in a luminous center, of a resolvable blaze of light." William Herschel, 1789 Abstract We provide a sample of 170 Galactic Globular Clusters (GCs) and analyse its spatial distribution properties.
    [Show full text]
  • The NTT Provides the Deepest Look Into Space 6
    The NTT Provides the Deepest Look Into Space 6. A. PETERSON, Mount Stromlo Observatory,Australian National University, Canberra S. D'ODORICO, M. TARENGHI and E. J. WAMPLER, ESO The ESO New Technology Telescope r on La Silla has again proven its extraor- - dinary abilities. It has now produced the "deepest" view into the distant regions of the Universe ever obtained with ground- or space-based telescopes. Figure 1 : This picture is a reproduction of a I.1 x 1.1 arcmin portion of a composite im- age of forty-one 10-minute exposures in the V band of a field at high galactic latitude in the constellation of Sextans (R.A. loh 45'7 Decl. -0' 143. The individual images were obtained with the EMMI imager/spectrograph at the Nas- myth focus of the ESO 3.5-m New Technolo- gy Telescope using a 1000 x 1000 pixel Thomson CCD. This combination gave a full field of 7.6 x 7.6 arcmin and a pixel size of 0.44 arcsec. The average seeing during these exposures was 1.0 arcsec. The telescope was offset between the indi- vidual exposures so that the sky background could be used to flat-field the frame. This procedure also removed the effects of cos- mic rays and blemishes in the CCD. More than 97% of the objects seen in this sub- field are galaxies. For the brighter galax- ies, there is good agreement between the galaxy counts of Tyson (1988, Astron. J., 96, 1) and the NTT counts for the brighter galax- ies.
    [Show full text]
  • Globular Clusters in the Inner Galaxy Classified from Dynamical Orbital
    MNRAS 000,1{17 (2019) Preprint 14 November 2019 Compiled using MNRAS LATEX style file v3.0 Globular clusters in the inner Galaxy classified from dynamical orbital criteria Angeles P´erez-Villegas,1? Beatriz Barbuy,1 Leandro Kerber,2 Sergio Ortolani3 Stefano O. Souza 1 and Eduardo Bica,4 1Universidade de S~aoPaulo, IAG, Rua do Mat~ao 1226, Cidade Universit´aria, S~ao Paulo 05508-900, Brazil 2Universidade Estadual de Santa Cruz, Rodovia Jorge Amado km 16, Ilh´eus 45662-000, Brazil 3Dipartimento di Fisica e Astronomia `Galileo Galilei', Universit`adi Padova, Vicolo dell'Osservatorio 3, Padova, I-35122, Italy 4Universidade Federal do Rio Grande do Sul, Departamento de Astronomia, CP 15051, Porto Alegre 91501-970, Brazil Accepted XXX. Received YYY; in original form ZZZ ABSTRACT Globular clusters (GCs) are the most ancient stellar systems in the Milky Way. There- fore, they play a key role in the understanding of the early chemical and dynamical evolution of our Galaxy. Around 40% of them are placed within ∼ 4 kpc from the Galactic center. In that region, all Galactic components overlap, making their disen- tanglement a challenging task. With Gaia DR2, we have accurate absolute proper mo- tions for the entire sample of known GCs that have been associated with the bulge/bar region. Combining them with distances, from RR Lyrae when available, as well as ra- dial velocities from spectroscopy, we can perform an orbital analysis of the sample, employing a steady Galactic potential with a bar. We applied a clustering algorithm to the orbital parameters apogalactic distance and the maximum vertical excursion from the plane, in order to identify the clusters that have high probability to belong to the bulge/bar, thick disk, inner halo, or outer halo component.
    [Show full text]
  • Archaeologic Inspection of the Milky Way Using Vibrations of a Fossil Seismic, Spectroscopic and Kinematic Characterization of a Binary Metal-Poor Halo Star
    Department of Physics and Astronomy Bachelor thesis in Physics, 15 credits Archaeologic inspection of the Milky Way using vibrations of a fossil Seismic, spectroscopic and kinematic characterization of a binary metal-poor Halo star Amanda Bystr¨om Supervisor: Marica Valentini Subject reader: Andreas Korn Examiner: Matthias Weiszflog Spring semester 2020 In collaboration with Leibniz-Institut fur¨ Astrophysik Potsdam Abstract - English The Milky Way has undergone several mergers with other galaxies during its lifetime. The mergers have been identified via stellar debris in the Halo of the Milky Way. The practice of mapping these mergers is called galactic ar- chaeology. To perform this archaeologic inspection, three stellar features must be mapped: chemistry, kinematics and age. Historically, the latter has been difficult to determine, but can today to high degree be determined through as- teroseismology. Red giants are well fit for these analyses. In this thesis, the red giant HE1405-0822 is completely characterized, using spectroscopy, asteroseis- mology and orbit integration, to map its origin. HE1405-0822 is a CEMP-r/s enhanced star in a binary system. Spectroscopy and asteroseismology are used in concert, iteratively to get precise stellar parameters, abundances and age. Its kinematics are analyzed, e.g. in action and velocity space, to see if it belongs to any known kinematical substructures in the Halo. It is shown that the mass accretion that HE1405-0822 has undergone has given it a seemingly younger age than probable. The binary probably transfered C- and s-process rich matter, but how it gained its r-process enhancement is still unknown. It also does not seem like the star comes from a known merger event based on its kinematics, and could possibly be a heated thick disk star.
    [Show full text]
  • N° PUBLICACIÓN FACULTAD DEPARTAMENTO Bellorin, J; Droguett, B
    Publicaciones 2019 Web of Science (WoS), según Journal Citation Reports: N° PUBLICACIÓN FACULTAD DEPARTAMENTO Bellorin, J; Droguett, B. Point-particle solution and the asymptotic flatness in 2+1D Horava 1 Cs. Básicas Depto. Física gravity PHYSICAL REVIEW D 100, 064021 (2019) Bellorin, J. Phenomenologically viable gravitational theory based on a 2 Cs. Básicas Depto. Física preferred foliation without extra modes General Relativity and Gravitation (2019) 51:133. Turek, O.; Goyeneche, D. 3 A generalization of circulant Hadamard and conference matrices Cs. Básicas Depto. Física Linear Algebra and its Applications, 2019; 569: 241-265 Appleby, M.; Bengtsson, I.; Flammia, S.; Goyeneche, D. 4 Tight frames, Hadamard matrices and Zauner’s conjecture Cs. Básicas Depto. Física J. Phys. A: Math. Theor., 2019; 52, 295301 (26pp) Cervera-Lierta, A; Latorre, J.I.; Goyeneche, D. 5 Quantum circuits for maximally entangled states Cs. Básicas Depto. Física PHYSICAL REVIEW A, 2019; 100, 022342 Sunil Kumar Maurya, Francisco Tello-Ortiz 6 Charged anisotropic strange stars in general relativity. Cs. Básicas Depto. Física The European Physical Journal C, 2019; 79:33 S. K. Maurya, Francisco Tello-Ortiz Generalized relativistic anisotropic compact star models by 7 Cs. Básicas Depto. Física gravitational decoupling. Eur. Phys. J. C, 2019; 79:85 Franciscto Tello-Ortiz, S.K Maurya, Abdelghani Errehymy, Ksh. Newton Singh & Mohamed Daoud 8 Anisotropic relativistic fluid spheres: an embedding class I approach Cs. Básicas Depto. Física Eur. Phys. J. C, 2019 Vol. 79; 885 Bhar, Piyali; Singh, Ksh. Newton; Tello-Ortiz, Francisco Compact star in Tolman-Kuchowicz spacetime in the background of 9 Cs. Básicas Depto. Física Einstein-Gauss-Bonnet gravity Eur.
    [Show full text]
  • Observational Aspects of Globular Cluster and Halo Stars in the GALAH Survey
    THE UNIVERSITY OF NEW SOUTH WALES DOCTORAL THESIS Observational aspects of globular cluster and halo stars in the GALAH survey Student: Supervisor: Mohd Hafiz MOHD SAADON Associate Professor Sarah MARTELL A thesis submitted in fulfillment of the requirements for the degree of Doctor of Philosophy in the School of Physics Faculty of Science The University of New South Wales 12 March 2021 i ii iii iv Declaration of Authorship I, Mohd Hafiz MOHD SAADON, declare that this thesis titled, “Observational aspects of globular cluster and halo stars in the GALAH survey” and the work presented in it are my own. I confirm that: • This work was done wholly or mainly while in candidature for a research degree at this University. • Where any part of this thesis has previously been submitted for a degree or any other qualification at this University or any other institution, this has been clearly stated. • Where I have consulted the published work of others, this is always clearly at- tributed. • Where I have quoted from the work of others, the source is always given. With the exception of such quotations, this thesis is entirely my own work. • I have acknowledged all main sources of help. Signed: Date: v “In loving memory of my grandmothers, Ramlah and Halijah, who wished to see me this far but could not be here anymore.” – your grandson. “To Amani, my sweet little angel, this thesis is your sibling.” – your father. vi THE UNIVERSITY OF NEW SOUTH WALES Abstract Doctor of Philosophy Observational aspects of globular cluster and halo stars in the GALAH survey by Mohd Hafiz MOHD SAADON This thesis is a study of the observational aspects of globular cluster and halo stars in the Galactic Archaeology with HERMES (GALAH) survey.
    [Show full text]
  • Blanco Decam Bulge Survey (BDBS) II: Project Performance, Data Analysis, and Early Science Results
    MNRAS 499, 2357–2379 (2020) doi:10.1093/mnras/staa2393 Advance Access publication 2020 September 3 Blanco DECam Bulge Survey (BDBS) II: project performance, data analysis, and early science results Christian I. Johnson ,1‹ Robert Michael Rich ,2 Michael D. Young,3 Iulia T. Simion,4 William I. Clarkson,5 Catherine A. Pilachowski,6 Scott Michael,6 Andrea Kunder,7 Andreas Koch8 and Anna Katherina Vivas 9 1Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA 2Department of Physics and Astronomy, UCLA, 430 Portola Plaza, Box 951547, Los Angeles, CA 90095-1547, USA 3Indiana University, University Information Technology Services, CIB 2709 E 10th Street, Bloomington, IN 47401 USA 4Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, 80 Nandan Road, Shanghai 200030, China Downloaded from https://academic.oup.com/mnras/article/499/2/2357/5900983 by guest on 23 October 2020 5Department of Natural Sciences, University of Michigan-Dearborn, 4901 Evergreen Rd. Dearborn, MI 48128, USA 6Indiana University Department of Astronomy, SW319, 727 E 3rd Street, Bloomington, IN 47405 USA 7Saint Martin’s University, 5000 Abbey Way SE, Lacey, WA 98503, USA 8Zentrum fur¨ Astronomie der Universitat¨ Heidelberg, Astronomisches Rechen-Institut, Monchhofstr.¨ 12, D-69120 Heidelberg, Germany 9Cerro Tololo Inter-American Observatory, NSF’s National Optical-Infrared Astronomy Research Laboratory, Casilla 603 La Serena, Chile Accepted 2020 August 6. Received 2020 August 6; in original form 2019 December 9 ABSTRACT The Blanco DECam Bulge Survey (BDBS) imaged more than 200 sq deg of the Southern Galactic bulge using the ugrizY filters of the Dark Energy Camera, and produced point spread function photometry of approximately 250 million unique sources.
    [Show full text]
  • Arxiv:1812.04999V1 [Astro-Ph.GA] 12 Dec 2018 Density Lying Well Inside the Bulge, And, If Proved to Be Genuine Clusters, Most Are Expected to Be of Low Mass
    Draft version December 13, 2018 Preprint typeset using LATEX style AASTeX6 v. 1.0 A SEQUOIA IN THE GARDEN: FSR 1758 - DWARF GALAXY OR GIANT GLOBULAR CLUSTER? a Rodolfo H. Barba´1, Dante Minniti2,3,4, Douglas Geisler5,1,7, Javier Alonso-Garc´ıa6,3, Maren Hempel2, Antonela Monachesi7,1, Julia I. Arias1, Facundo A. Gomez´ 7,1 1Departamento de F´ısica y Astronom´ıa, Universidad de La Serena, Avenida Juan Cisternas 1200, La Serena, Chile. 2Depto. de Ciencias F´ısicas,Facultad de Ciencias Exactas, Universidad Andres Bello, Fernandez Concha 700, Las Condes, Santiago, Chile. 3Millennium Institute of Astrophysics, Av. Vicuna Mackenna 4860, 782-0436, Santiago, Chile. 4Vatican Observatory, V00120 Vatican City State, Italy. 5Departamento de Astronomia, Casilla 160-C, Universidad de Concepcion, Chile. 6Centro de Astronom´ıa(CITEVA), Universidad de Antofagasta, Av. Angamos 601, Antofagasta, Chile. 7Instituto de Investigaci´onMultidisciplinar en Ciencia y Tecnolog´ıa,Universidad de La Serena, Ra´ulBitr´an1305, La Serena, Chile. ABSTRACT We present the physical characterization of FSR 1758, a new large, massive object very recently discovered in the Galactic Bulge. The combination of optical data from the 2nd Gaia Data Release (GDR2) and the DECam Plane Survey (DECaPS), and near-IR data from the VISTA Variables in the V´ıaL´acteaExtended Survey (VVVX) led to a clean sample of likely members. Based on this integrated dataset, position, distance, reddening, size, metallicity, absolute magnitude, and proper motion of this object are measured. We estimate the following parameters: α = 17 : 31 : 12, δ = −39 : 48 : 30 (J2000), D = 11:5 ± 1:0 kpc, E(J − Ks) = 0:20 ± 0:03 mag, Rc = 10 pc, Rt = 150 −1 −1 pc,[F e=H] = −1:5 ± 0:3 dex, Mi < −8:6 ± 1:0, µα = −2:85 mas yr , and µδ = 2:55 mas yr .
    [Show full text]
  • Partitioning the Galactic Halo with Gaussian Mixture Models
    Research in Astron. Astrophys. Vol.0 (20xx) No.0, 000–000 Research in http://www.raa-journal.org http://www.iop.org/journals/raa Astronomy and (LATEX: 2020-0400.tex; printed on January 11, 2021; 13:55) Astrophysics Partitioning the Galactic Halo with Gaussian Mixture Models Xi-Long Liang1;2, Yu-Qin Chen2;1, Jing-Kun Zhao2;1 and Gang Zhao2;1 1 School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing 100049, China 2 CAS Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences,Beijing 100101, China; [email protected] Received 2020 November 6; accepted 2021 January 5 Abstract The Galactic halo is supposed to form from merging with nearby dwarf galax- ies. In order to probe different components of the Galactic halo, we have applied the Gaussian Mixture Models method to a selected sample of metal poor stars with [Fe/H] < −0:7 dex in the APOGEE DR16 catalogue based on four-parameters, metallicity, [Mg/Fe] ratio and spatial velocity (VR, Vφ). Nine groups are identified with four from the halo (group 1, 3, 4 and 5), one from the thick disk (group 6), one from the thin disk (group 8) and one from dwarf galaxies (group 7) by analyzing their distributions in the ([M/H], [Mg/Fe]), (VR, Vφ), (Zmax, eccentricity), (Energy, Lz) and ([Mg/Mn], [Al/Fe]) coordinates. The rest two groups are respectively caused by observational effect (group 9) and the cross section component (group 2) between the thin disk and the thick disk. It is found that in the extremely outer accreted halo (group 1), stars born in the Milky Way can not be distinguished from those accreted from other galaxies either chemically or kine- matically.
    [Show full text]
  • Globular Clusters 1
    Globular Clusters 1 www.FaintFuzzies.com Globular Clusters 2 www.FaintFuzzies.com Globular Clusters (Includes all known globulars in the Milky Way above declination of -50º plus some extras) by Alvin Huey www.faintfuzzies.com Last updated: March 27, 2014 Globular Clusters 3 www.FaintFuzzies.com Other books by Alvin H. Huey Hickson Group Observer’s Guide The Abell Planetary Observer’s Guide Observing the Arp Peculiar Galaxies Downloadable Guides by FaintFuzzies.com The Local Group Selected Small Galaxy Groups Galaxy Trios and Triple Systems Selected Shakhbazian Groups Globular Clusters Observing Planetary Nebulae and Supernovae Remnants Observing the Abell Galaxy Clusters The Rose Catalogue of Compact Galaxies Flat Galaxies Ring Galaxies Variable Galaxies The Voronstov-Velyaminov Catalogue – Part I and II Object of the Week 2012 and 2013 – Deep Sky Forum Copyright © 2008 – 2014 by Alvin Huey www.faintfuzzies.com All rights reserved Copyright granted to individuals to make single copies of works for private, personal and non-commercial purposes All Maps by MegaStarTM v5 All DSS images (Digital Sky Survey) http://archive.stsci.edu/dss/acknowledging.html This and other publications by the author are available through www.faintfuzzies.com Globular Clusters 4 www.FaintFuzzies.com Table of Contents Globular Cluster Index ........................................................................ 6 How to Use the Atlas ........................................................................ 10 The Milky Way Globular Clusters ....................................................
    [Show full text]
  • 1.1 RR Lyrae Stars
    Universita` degli studi di Roma “Tor Vergata” Facolta` di Scienze Matematiche, Fisiche e Naturali Dottorato di Ricerca in Astronomia XIX ciclo (2003-2006) SELF-CONSISTENT DISTANCE SCALES FOR POPULATION II VARIABLES Marcella Di Criscienzo Coordinator: Supervisors: PROF. R. BUONANNO PROF. R. BUONANNO PROF.SSA F. CAPUTO DOTT.SSA M. MARCONI Vedere il mondo in un granello di sabbia e il cielo in un fiore di campo tenere l’infinito nel palmo della tua mano e l'eternita´ in un ora. (William Blake) ii Dedico questa tesi a: Mamma e Papa´ Sarocchia Giuliana Marcella & Vincenzo Massimo Filippina Caputo Massimo Capaccioli Roberto Buonanno che mi aiutarono a trovare la strada, e a Tommaso che su questa strada ha viaggiato con me per quasi tutto il tempo Contents The scientific project xv 1 Population II variables 1 1.1 RR Lyrae stars 3 1.1.1 Observational properties 4 1.1.2 Evolutionary properties 6 1.1.3 RR Lyrae as standard candles 8 1.1.4 RR Lyrae in Globular Clusters 9 1.2 Population II Cepheids 13 1.2.1 Present status of knowledge 13 2 Some remarks on the pulsation theory and the computational methods 15 2.1 The pulsation cycle: observations 15 2.2 Pulsation mechanisms 17 2.3 Theoretical approches to stellar pulsation 19 2.4 Computational methods 23 3 Updated pulsation models of RR Lyrae and BL Herculis stars 25 3.1 RR Lyrae (Di Criscienzo et al. 2004, ApJ, 612; Marconi et al., 2006, MNRAS, 371) 25 3.1.1 The instability strip 30 3.1.2 Pulsational amplitudes 31 3.1.3 Some important relations for RR Lyrae studies 36 3.1.4 New results in the SDSS filters 39 3.2 BL Herculis stars (Marconi & Di Criscienzo, 2006, A&A, in press) 43 iv REFERENCES 3.2.1 Light curves and pulsation amplitudes 46 3.2.2 The instability strip 48 4 Comparison with observed RR Lyrae stars and Population II Cepheids 51 4.1 RR Lyrae 52 4.1.1 Comparison of models in Johnson-Cousin filters with current ob- servations (Di Criscienzo et al.
    [Show full text]
  • Dynamical Modelling of Stellar Systems in the Gaia Era
    Dynamical modelling of stellar systems in the Gaia era Eugene Vasiliev Institute of Astronomy, Cambridge Synopsis Overview of dynamical modelling Overview of the Gaia mission Examples: Large Magellanic Cloud Globular clusters Measurement of the Milky Way gravitational potential Fred Hoyle vs. the Universe What does \dynamical modelling" mean? It does not refer to a simulation (e.g. N-body) of the evolution of a stellar system. Most often, it means \modelling a stellar system in a dynamical equilibrium" (used interchangeably with \steady state"). vs. the Universe What does \dynamical modelling" mean? It does not refer to a simulation (e.g. N-body) of the evolution of a stellar system. Most often, it means \modelling a stellar system in a dynamical equilibrium" (used interchangeably with \steady state"). Fred Hoyle What does \dynamical modelling" mean? It does not refer to a simulation (e.g. N-body) of the evolution of a stellar system. Most often, it means \modelling a stellar system in a dynamical equilibrium" (used interchangeably with \steady state"). Fred Hoyle vs. the Universe 3D Steady-state assumption =) Jeans theorem: f (x; v)= f I(x; v;Φ) observations: 3D { 6D integrals of motion (≤ 3D?), e.g., I = fE; L;::: g Why steady state? Distribution function of stars f (x; v; t) satisfies [sometimes] the collisionless Boltzmann equation: @f (x; v; t) @f (x; v; t) @Φ(x; t) @f (x; v; t) + v − = 0: @t @x @x @v Potential , mass distribution @f (x; v; t) ; t ; t ; t + @t 3D observations: 3D { 6D integrals of motion (≤ 3D?), e.g., I = fE; L;:::
    [Show full text]