I am a Research Fellow at the Research School of Astronomy and Astrophysics (Australian National University). I received my undergraduate degree in physics from the Universidad Nacional Mayor de San Marcos (Peru), the oldest university in the Americas. I obtained my PhD in astronomy at the Universidade de Sao Paulo, gathering the most complete list of atomic data for spectral synthesis in the infrared, and for further work on population synthesis. During my PhD I also obtained oxygen abundances from infrared OH lines, showing that [O/Fe] is ~ constant in halo stars. Working with B. Barbuy, we obtained beautiful IR spectra of extremely high S/N, in order to detect tiny IR-OH lines at metallicities as low as [Fe/H] = -3. Another important study done with B. Barbuy was the determination of chemical abundances in giants of the Bulge Globular Cluster NGC 6553.

I spent two years (2003-2005) at Caltech working with J. Cohen on abundance variations in GC stars, and on a survey for finding the oldest stars in our Galaxy. During my time in Pasadena I also collaborated with I. Ramirez (U. Texas) on the calibration of the fundamental properties of FGK stars. Our new IRFM temperature scale (Ramirez & Melendez 2005a,b) has been applied to the determination of lithium and oxygen abundances in metal-poor stars, a work with important implications on Big Bang Nucleosynthesis and the evolution of the light elements.

Since Sept/2005 I'm working with M. Asplund (RSAA, ANU), and my main interests are the physical (e.g. temperature, mass, luminosity, radius) and chemical properties (e.g. iron, carbon, oxygen, lithium) of cool (FGK) stars, the evolution of the Chemical Elements in the Universe, the discovery of solar twins, and the fundamental properties of possible host stars of habitable systems in our Galaxy.

     HIP 56948 ( HD 101364): The Best Solar Twin ! (ApJ, 669, L89):

HIP 56948 is probably the best candidate for life outside the Solar System (Melendez & Ramirez 2007, ApJ Letters, in press). This star is almost identical to the Sun, although perhaps somewhat more luminous (about 1+/-1 Gyr more evolved than the Sun). Below some notes about this discovery.

·  Finding chart (circle in Draco) (© Stellarium, 3/oct/07)

·  Zoom around HIP 56948 (10 x 10 arcmin, from DSS2: http://archive.stsci.edu/dss/, 3/oct/07)

·  Figure of relative chemical composition (dashed lines show agreement within +/- 10%), by J.M./I.R. (3/oct/07)

·  The Sun has a twin, by Ken Croswell (Earth & Sky, Oct/07)

·  Sun's 'Twin' an ideal hunting ground for alien life, by David Shiga (New Scientist, 3/oct/07)

·  Expertos peruanos descubren una estrella 'gemela' de nuestro Sol, by Angel Diaz (El Mundo, 4/oct/07)

     Our Solar Twin In The News ! (articles & notes about HD 98618):

·  A Solar Twin in the Big Dipper, by Ken Croswell (10/mar/06) MSO version including some images

·  New solar twin could shed light on another Earth, ANU media release (23/mar/06)

·  Bright future for Sun's twin, NATURE News (24/mar/06)

·  A Nearby Twin of the Sun, Universe Today (24/mar/06)

·  Descoberta uma “Gemea Solar”, Planetario da Cidade do Rio de Janeiro (mar/06)

·  Scoperto un gemello del Sole a 126 anni luce dalla Terra, Lanci (27/mar/06)

·  Zwillingsschwester der Sonne, Die Presse [Tech & Science] (28/mar/06)

·  Buscando Gemelos del Sol, Neofronteras (6/abr/06)

·  Descubren Estrella Gemela de Nuestro Sol, El Universal (7/abr/06)

·  Un Cercano Gemelo del Sol, Astroseti (8/abr/06)

·  Also in New Scientist (8/abr/06, page 17); Sky & Space (March/April 2006, page 12), Australasian Science (May/2006)

    PUBLICATIONS

·  31 refereed journal publications (22 as 1st or 2nd author)

·  11 papers in conference proceedings

·  h-index = 15 (using ADS), m-index = 1.6

·   Here is my CV

    FIELDS OF INTEREST

·  Atomic and Molecular Spectroscopy

·  Chemical Composition of Stars

·  Calibration of Fundamental Stellar Parameters

·  Metal-Poor Stars, Stars with Planets, Solar Twins, Habitability

   COLLABORATORS
    Martin Asplund (Chemical Abundances in Halo and Bulge Stars), Ivan Ramirez (Fundamental Stellar Parameters, Solar Twins) , Beatriz Barbuy (Chemical Abundances in Bulge GCs), Judy Cohen (Globular Clusters and Mg isotopes), Wolfgang Hayek (The Bulge Globular Cluster NGC 6553).

    FORMER COLLABORATORS
    Bruno Castilho (IR boron lines), Nataliya Shchukina (NLTE Oxygen and Iron Abundances), Jose Robles, Katie Dodds-Eden (Solar twins), Paula Coelho (spectral synthesis & stellar library), Hanumant Sawant and “Guga” Fernandes (Solar Bursts).

    TEMPERATURE AND BOLOMETRIC FLUX CALIBRATIONS

·  The Effective Temperature Scale of FGK Stars. I. Determination of Temperatures and Angular Diameters with the Infrared Flux Method, I. Ramírez & J. Meléndez 2005, ApJ, 626, 446

·  The Effective Temperature Scale of FGK Stars. II. Teff/color/[Fe/H] calibrations, I. Ramírez & J. Meléndez 2005, ApJ, 626, 465

·  BC for Solar Metallicity Dwarfs: (Melendez, Dodds-Eden & Robles 2006, ApJ, 641, L133)

    ATOMIC DATA

·  Line list of atomic lines in the near infrared J and H bands (Melendez & Barbuy 1999)

·  gf-values for Fe II lines (Melendez et al. 2006, ApJ 642, 1082; complete list in Melendez & Barbuy 2006)

    SOLAR TWINS

·  HIP 56948 (HD 101364) : A Solar Twin with a Low Lithium Abundance (Melendez & Ramirez 2007, ApJ Letters, in press)

·  HD 98618: A Star Closely Resembling the Sun (Melendez, Dodds-Eden & Robles 2006, ApJ, 641, L133)

    WORKS IN PREPARATION

·  Fundamental Parameters of Stars with Planets (Melendez & Ramirez 2008 ??)

·  Li-6 in halo stars (Asplund & Melendez 2008?; Melendez et al. 2008. ??)

·  Comparative chemical evolution of the Galactic Bulge / Halo / Thick Disk and Thin Disk (Melendez et al. 2008??)

·  Mg isotopes in M71 giants (Melendez & Cohen 2008 ???)

    ATLAS

·  Arcturus Infrared Atlas (1-2 um), (2-2.5um)

·  Solar Infrared Atlas (Wallace et al.) (1.1-2.5 um)

    E(B-V) E(B-V) using several (maps), including a mean E(B-V) ([Fe/H]) --!>