Start year
2010
Organizational Unit
Organizing institutions
Grants related:
General
Description
Stellar spectroscopy allows us to determine the properties and chemical compositions of stars. From this information for stars of different ages in the Milky Way, it is possible to reconstruct the chemical evolution of the Galaxy, as well as the origin of the elements heavier than boron, created mainly in stellar interiors. It is also possible to study stellar formation, and the formation of the Galaxy, from the signature of the Galactic potential on the stellar orbits, and the distributions of mass, ages, and the abundance of heavy elements.
Obtaining high-resolution spectra, as necessary for studies of chemical compositions, requires advanced and efficient instrumentation. This is particularly true for research that calls for large stellar samples, which demands the observation of hundreds or thousands of sources simultaneously. Efficiency requires that the data processing and analysis are performed in an automated way.
The interpretation of spectra is based on physical models of the atmospheres of the stars, from where the light that we observe escapes the stars. The main ingredients for building such models are the fluid dynamics, and the properties of the atoms, ions, and molecules, especially regarding their interactions with the radiation coming from the stellar interior.
Once we have a plausible model, it is possible to compute in detail how the radiation propagates through the stellar atmosphere, and the emergent spectrum, which can then be iteratively compared with the observations to refine the model.
This project covers three different research fronts:
- Improving model atmospheres and simulations of stellar spectra.
- Developing tools for acquisition, reduction, and analysis of spectroscopic observations, in particular for the determination of chemical abundances in stars.
- Designing, preparing, and executing spectroscopic studies of stars aimed at understanding a) the most relevant aspects of the physics of stellar atmospheres, b) the formation and evolution of stars, c) the origin of the chemical elements, and d) the formation, structure, and evolution of the Milky Way galaxy.
Members
Principal investigator
Carlos
Allende Prieto
Project staff
Prof.
Rafael
Rebolo López
Yeisson Fabián
Martínez Osorio
Thomas
Masseron
Collaborators
Andrés
Asensio Ramos
Juan
Calvo Tovar
Jorge
Casares Velázquez
José Alfonso
López Aguerri
Claudio
Dalla Vecchia
Domingo Aníbal
García Hernández
Ramón
García López
Fabio
Tenegi Sanginés
FRANCISCO SHU
KITAURA JOYANES
Jonay Isai
González Hernández
Olga María
Zamora Sánchez
Pablo
Rodríguez Gil
Dr.
I. Hubeny
Dr.
D.L. Lambert
Dr.
L. Koesterke
Dr.
I. Ramirez
Dr.
M. Shetrone
Dr.
J.J. Hermes
Dr.
D. E. Winget
Dr.
B. Castanheira
Dr.
M. Asplund
Dr.
W. Brown
Dr.
M. Kilic
Dr.
S. Majewski
Dr.
R. Schiavon
Dr.
J. Holtzman
Dr.
H.G. Ludwig
Dr.
T. Beers
Dr.
V. S. Smith
Dr.
Y. Sun Lee
Dr.
M. Cropper
Dr.
D. Kawata
Dr.
M. P. Ruffoni
Dr.
J. C. Pickering
Dr.
K. Cunha
Dr.
C. Rockosi
Dr.
Andrew Cooper
Dr.
Boris Gaensicke
Results
- Complete the installation and commissioning of HORuS on GTC
- Discover two new stars with more than 100,000 times less iron than the Sun
- Complete the classification of all the APOGEE spectra with K-means
- Publish a complete collection of model stellar spectra for stars O to M
- Identify the signature of chemical diffusion in the atmospheres of the stars in the cluster M67
Scientific activity
Related publications
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The Shapes of Stellar SpectraStellar atmospheres separate the hot and dense stellar interiors from the emptiness of space. Radiation escapes from the outermost layers of a star, carrying direct physical information. Underneath the atmosphere, the very high opacity keeps radiation thermalized and resembling a black body with the local temperature. In the atmosphere the opacityAllende Prieto, Carlos
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32023 -
Survey Operations for the Dark Energy Spectroscopic InstrumentThe Dark Energy Spectroscopic Instrument (DESI) survey is a spectroscopic survey of tens of millions of galaxies at 0 < z < 3.5 covering 14,000 sq. deg. of the sky. In its first 1.1 yr of survey operations, it has observed more than 14 million galaxies and 4 million stars. We describe the processes that govern DESI's observations of the 15,000Schlafly, Edward F. et al.
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122023 -
The <SUP>12</SUP>C/<SUP>13</SUP>C isotopic ratio at the dawn of chemical evolutionContext. The known mega metal-poor (MMP) and hyper metal-poor (HMP) stars, with [Fe/H] < −6.0 and < −5.0, respectively, likely belong to the CEMP-no class, namely, carbon-enhanced stars with little or no second peak neutron-capture elements. They are likely second-generation stars, and the few elements measurable in their atmospheres are used toMolaro, P. et al.
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112023 -
Optical and Infrared Counterparts of the X-Ray Sources Detected in the Chandra Cygnus OB2 Legacy SurveyThe young massive OB association Cygnus OB2, in the Cygnus X complex, is the closest (~1400 pc) star-forming region to the Sun hosting thousands of young low-mass stars and up to 1000 OB stars, among which are some of the most massive stars known in our Galaxy. This region holds great importance for several fields of modern astrophysics, such asGuarcello, M. G. et al.
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112023 -
The Pristine survey - XXII. A serendipitous discovery of an extremely Li-rich very metal-poor giant and a new method of <SUP>6</SUP>Li/<SUP>7</SUP>Li isotope measurementWe report the serendipitous discovery of a very metal-poor (VMP) Li-rich giant star (T eff = 4690 ± 80 K, log g = 1.34 ± 0.13, [Fe/H] = -2.43 ± 0.07). We analyse the Li I 6103 and 6707 Å lines accounting for departures from local thermodynamic equilibrium (NLTE) and correcting for 3D effects using literature data, which yields a lithium abundanceSitnova, T. M. et al.
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122023 -
GTC Follow-up Observations of Very Metal-poor Star Candidates from DESIThe observations from the Dark Energy Spectroscopic Instrument (DESI) will significantly increase the numbers of known extremely metal-poor stars by a factor of ~10, improving the sample statistics to study the early chemical evolution of the Milky Way and the nature of the first stars. In this paper we report follow-up observations with highAllende Prieto, Carlos et al.
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112023 -
A Tale of Two Disks: Mapping the Milky Way with the Final Data Release of APOGEEWe present new maps of the Milky Way disk showing the distribution of metallicity ([Fe/H]), α-element abundances ([Mg/Fe]), and stellar age, using a sample of 66,496 red giant stars from the final data release (DR17) of the Apache Point Observatory Galactic Evolution Experiment survey. We measure radial and vertical gradients, quantify theImig, Julie et al.
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92023 -
The Gaia-ESO Survey: Homogenisation of stellar parameters and elemental abundancesThe Gaia-ESO Survey is a public spectroscopic survey that targeted ≳10 5 stars covering all major components of the Milky Way from the end of 2011 to 2018, delivering its final public release in May 2022. Unlike other spectroscopic surveys, Gaia-ESO is the only survey that observed stars across all spectral types with dedicated, specialisedHourihane, A. et al.
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82023 -
Decoding the compositions of four bright r-process-enhanced starsThere has been a concerted effort in recent years to identify the astrophysical sites of the r-process that can operate early in the galaxy. The discovery of many r-process-enhanced (RPE) stars (especially by the R-process Alliance collaboration) has significantly accelerated this effort. However, only limited data exist on the detailed elementalSaraf, Pallavi et al.
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102023 -
iNNterpol: High-precision interpolation of stellar atmospheres with a deep neural network using a 1D convolutional auto encoder for feature extractionContext. Given the widespread availability of grids of models for stellar atmospheres, it is necessary to recover intermediate atmospheric models by means of accurate techniques that go beyond simple linear interpolation and capture the intricacies of the data. Aims: Our goal is to establish a reliable, precise, lightweight, and fast method forWestendorp Plaza, C. et al.
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72023 -
Opacity for realistic 3D MHD simulations of cool stellar atmospheresContext. Realistic three-dimensional time-dependent simulations of stellar near-surface convection employ the opacity binning method for the efficient and accurate computation of the radiative energy exchange. The method provides several orders of magnitude of speedup, but its implementation includes a number of free parameters. Aims: Our aim is toPerdomo García, A. et al.
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72023 -
Stellar Characterization and Radius Inflation of Hyades M-dwarf Stars from the APOGEE SurveyWe present a spectroscopic analysis of a sample of 48 M-dwarf stars (0.2 M ⊙ < M < 0.6 M ⊙) from the Hyades open cluster using high-resolution H-band spectra from the Sloan Digital Sky Survey/Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. Our methodology adopts spectrum synthesis with LTE MARCS model atmospheres, along withWanderley, Fábio et al.
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72023 -
sMILES SSPs: a library of semi-empirical MILES stellar population models with variable [α/Fe] abundancesWe present a new library of semi-empirical stellar population models that are based on the empirical MILES and semi-empirical sMILES stellar libraries. The models span a large range of age and metallicity, in addition to an [α/Fe] coverage from -0.2 to +0.6 dex, at MILES resolution (FWHM = $2.5\,$ Å) and wavelength coverage ($3540.5-7409.6\,$ Å)Knowles, Adam T. et al.
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82023 -
The Pristine Inner Galaxy Survey (PIGS) VII: a discovery of the first inner Galaxy CEMP-r/s starWell-studied very metal-poor (VMP, [Fe/H] <-2) stars in the inner Galaxy are few in number, and they are of special interest because they are expected to be among the oldest stars in the Milky Way. We present high-resolution spectroscopic follow-up of the carbon-enhanced metal-poor (CEMP) star Pristine_184237.56-260624.5 (hereafter Pr184237)Mashonkina, L. et al.
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82023 -
Overview of the DESI Milky Way SurveyWe describe the Milky Way Survey (MWS) that will be undertaken with the Dark Energy Spectroscopic Instrument (DESI) on the Mayall 4 m telescope at the Kitt Peak National Observatory. Over the next 5 yr DESI MWS will observe approximately seven million stars at Galactic latitudes |b| > 20°, with an inclusive target selection scheme focused on theCooper, Andrew P. et al.
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42023 -
DAHe white dwarfs from the DESI SurveyA new class of white dwarfs, dubbed DAHe, that present Zeeman-split Balmer lines in emission has recently emerged. However, the physical origin of these emission lines remains unclear. We present here a sample of 21 newly identified DAHe systems and determine magnetic field strengths and (for a subset) periods that span the ranges of ≃6.5-147 MGManser, Christopher J. et al.
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62023 -
The Spectroscopic Data Processing Pipeline for the Dark Energy Spectroscopic InstrumentWe describe the spectroscopic data processing pipeline of the Dark Energy Spectroscopic Instrument (DESI), which is conducting a redshift survey of about 40 million galaxies and quasars using a purpose-built instrument on the 4 m Mayall Telescope at Kitt Peak National Observatory. The main goal of DESI is to measure with unprecedented precision theGuy, J. et al.
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42023 -
DESI Observations of the Andromeda Galaxy: Revealing the Immigration History of Our Nearest NeighborWe present Dark Energy Spectroscopic Instrument (DESI) observations of the inner halo of M31, which reveal the kinematics of a recent merger-a galactic immigration event-in exquisite detail. Of the 11,416 sources studied in 3.75 hr of on-sky exposure time, 7438 are M31 sources with well-measured radial velocities. The observations reveal intricateDey, Arjun et al.
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22023 -
The Pristine survey - XX. GTC follow-up observations of extremely metal-poor stars identified from Pristine and LAMOSTUltra-metal-poor stars ($\rm {[Fe/H]} \lt -4.0$) are very rare, and finding them is a challenging task. Both narrow-band photometry and low-resolution spectroscopy have been useful tools for identifying candidates, and in this work, we combine both approaches. We cross-matched metallicity-sensitive photometry from the Pristine survey with the lowArentsen, Anke et al.
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32023 -
The pristine nature of SMSS 1605−1443 revealed by ESPRESSOContext. SMSS J160540.18−144323.1 is the carbon-enhanced metal-poor (CEMP) star with the lowest iron abundance ever measured, [Fe/H] = −6.2, which was first reported with the SkyMapper telescope. The carbon abundance is A(C)≈6.1 in the low-C band, as the majority of the stars in this metallicity range. Yet, constraining the isotopic ratio of keyAguado, D. S. et al.
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12023
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SEVERO OCHOA 2016 - 2019
The IAC is an internationalized Spanish research centre aiming to achieve major advances in the understanding of the laws that govern the origin and evolution of the various forms of matter/energy in the Universe. Outstanding results are expected in key areas of research such as Solar physics, Sun-Earth connections, Exoplanetary systems, Solar
Rafael
Rebolo López
