Concept

Sommet de la branche des géantes rouges

Publications associées (30)

Small-amplitude Red Giants Elucidate the Nature of the Tip of the Red Giant Branch as a Standard Candle

Richard Irving Anderson, Nolan Wayne Koblischke

The tip of the red giant branch (TRGB) is an important standard candle for determining luminosity distances. Although several 105 small-amplitude red giant stars (SARGs) have been discovered, variability was previously considered irrelevant for the TRGB as ...

Iop Publishing Ltd2024

Standardized Luminosity of the Tip of the Red Giant Branch Utilizing Multiple Fields in NGC 4258 and the CATs Algorithm

Richard Irving Anderson

The tip of the red giant branch provides a luminous standard candle for calibrating distance ladders that reach Type Ia supernova (SN Ia) hosts. However, recent work reveals that tip measurements vary at the similar to 0.1 mag level for different stellar p ...

Iop Publishing Ltd2023

The evolution of the Milky Way's thin disc radial metallicity gradient with K2 asteroseismic ages

Saniya Khan

The radial metallicity distribution of the Milky Way's disc is an important observational constraint for models of the formation and evolution of our Galaxy. It informs our understanding of the chemical enrichment of the Galactic disc and the dynamical pro ...

Oxford Univ Press2023

The extended stellar halo' of the Ursa Minor dwarf galaxy

Pascale Jablonka

Stellar candidates in the Ursa Minor (UMi) dwarf galaxy have been found using a new Bayesian algorithm applied to Gaia EDR3 data. Five of these targets are located in the extreme outskirts of UMi, from similar to 5 to 12 elliptical half-light radii (r h), ...

OXFORD UNIV PRESS2023

Discovery of a Binary-origin Classical Cepheid in a Binary System with a 59 day Orbital Period

Richard Irving Anderson

We report the discovery of a surprising binary configuration of the double-mode Cepheid OGLE-LMC-CEP-1347 pulsating in the first (P-1= 0.690 days) and second-overtone (P-2= 0.556 days) modes. The orbital period (P-orb= 59 days) of the system is five times ...

Iop Publishing Ltd2022

Stellar metallicity gradients of Local Group dwarf galaxies

Pascale Jablonka, Yves Revaz

Aims. We explore correlations between the strength of metallicity gradients in Local Group dwarf galaxies and their stellar mass, star formation history timescales, and environment. Methods. We performed a homogeneous analysis of literature spectroscopic d ...

2022

The Pristine survey - XV. A CHIT ESPaDOnS view on the Milky Way halo and disc populations

Pascale Jablonka, Carmela Lardo, Romain Ely Roland Lucchesi

We present a one-dimensional, local thermodynamic equilibrium homogeneous analysis of 132 stars observed at high resolution with ESPaDOnS. This represents the largest sample observed at high resolution (R similar to 40 000) from the Pristine survey. This s ...

OXFORD UNIV PRESS2022

Cepheids with Giant Companions. I. Revealing a Numerous Population of Double-lined Binary Cepheids* (dagger)

Richard Irving Anderson

Masses of classical Cepheids of 3-11 M are predicted by theory but those measured clump between 3.6-5 M. As a result, their mass-luminosity relation is poorly constrained, impeding our understanding of basic stellar physics and the Leavitt Law. All Cepheid ...

2021

Leveraging HST with MUSE: II. Na-abundance variations in intermediate age star clusters

Carmela Lardo

Ancient (>10 Gyr) globular clusters (GCs) show chemical abundance variations in the form of patterns among certain elements, e.g. N correlates with Na and anticorrelates with O. Recently, N abundance spreads have also been observed in massive star clusters ...

OXFORD UNIV PRESS2020

Chromosome maps of young LMC clusters: an additional case of coeval multiple populations

Carmela Lardo

Recent studies have revealed that the multiple populations (MPs) phenomenon does not occur only in ancient and massive Galactic globular clusters (GCs), but it is also observed in external galaxies, where GCs sample a wide age range with respect to the Mil ...

OXFORD UNIV PRESS2020

The Hidden Past of M92: Detection and Characterization of a Newly Formed 17 degrees Long Stellar Stream Using the Canada-France Imaging Survey

Nicolas Lawrence Etienne Longeard

We present an analysis of the structure, kinematics, and orbit of a newly found stellar stream emanating from the globular cluster M92 (NGC 6341). This stream was discovered in an improved matched-filter map of the outer Galaxy, based on a "color-color-mag ...

IOP PUBLISHING LTD2020

Spectroscopic Orbits Of Three Dwarf Barium Stars

Pierre North

Barium stars are thought to result from binary evolution in systems wide enough to allow the more massive component to reach the asymptotic giant branch and eventually become a CO white dwarf. While Ba stars were initially known only among giant or subgian ...

OBSERVATORY2020

The chemical evolution of the dwarf spheroidal galaxy Sextans

Pascale Jablonka, Carmela Lardo, Pierre North, Romain Ely Roland Lucchesi, Romaine Theler

We present our analysis of the FLAMES dataset targeting the central 25 ' region of the Sextans dwarf spheroidal galaxy (dSph). This dataset is the third major part of the high-resolution spectroscopic section of the ESO large program 171.B-0588(A) obtained ...

EDP SCIENCES S A2020

Lithium in red giant stars: Constraining non-standard mixing with large surveys in the Gaia era

Pierre North

Context. Li is extensively known to be a good tracer of non-standard mixing processes occurring in stellar interiors. Aims. We present the results of a new large Li survey in red giant stars and combine it with surveys from the literature to probe the impa ...

EDP SCIENCES S A2020

Environmental processing in cluster core galaxies at z=1.7

Gianluca Castignani

Today, the brightest cluster galaxies (BCGs) are passive and very massive galaxies at the center of their clusters, and they still accrete mass through swallowing companions and gas from cooling flows. However their formation history is not well known. We ...

2020

Barium and related stars, and their white-dwarf companions

Pierre North, Conrad Johnston, Shreeya Sushil Shetye

Barium (Ba) dwarfs and CH subgiants are the less evolved analogues of Ba and CH giants. They are F- to G-type main-sequence stars polluted with heavy elements by their binary companions when the companion was on the asymptotic giant branch (AGB). This comp ...

EDP SCIENCES S A2019

Constant light element abundances suggest that the extended P1 in NGC 2808 is not a consequence of CNO-cycle nucleosynthesis

Carmela Lardo

Recent photometric results have identified a new population among globular cluster stars. This population, referred to as the 'extended P1', has been suggested to be the manifestation of a new abundance pattern where the initial mass fraction of He changes ...

OXFORD UNIV PRESS2019

IC 4499 revised: Spectro-photometric evidence of small light-element variations

Carmela Lardo

It has been suggested that IC 4499 is one of the very few old globulars to not host multiple populations with light-element variations. To follow-up on this very interesting result, here we have made use of accurate HST photometry and FLAMES at VLT high-re ...

EDP SCIENCES S A2018

The Gaia-ESO Survey: properties of newly discovered Li-rich giants

Carmela Lardo, Joao André Gomes de Sá e Sousa, Fadi Atef Bayoud

Aims. We report 20 new lithium-rich giants discovered within the Gaia-ESO Survey, including the first Li-rich giant with an evolutionary stage confirmed by CoRoT (Convection, Rotation and planetary Transits) data. We present a detailed overview of the prop ...

EDP SCIENCES S A2018

The formation of the Milky Way halo and its dwarf satellites; a NLTE-1D abundance analysis

Pascale Jablonka, Pierre North

We present a homogeneous set of accurate atmospheric parameters for a complete sample of very and extremely metal-poor stars in the dwarf spheroidal galaxies (dSphs) Sculptor, Ursa Minor, Sextans, Fornax, Botes I, Ursa Major II, and Leo IV. We also deliver ...

Edp Sciences S A2017