Publications (80)
The outer disc in shambles: blind detection of Monoceros and ACS with Gaia's astrometric sample
P. Ramos, T. Antoja, C. Mateu +5
The astrometric sample of Gaia allows us to study the outermost Galactic disc, the halo and their interface. It is precisely at the very edge of the disc where the effects of exter…
Ceci n'est pas a globular cluster: the metallicity distribution of the stellar system Terzan 5
Davide Massari, A. Mucciarelli, F. R. Ferraro +9
We present new determinations of the iron abundance for 220 stars belonging to the stellar system Terzan 5 in the Galactic bulge. The spectra have been acquired with FLAMES at the…
Perturbed distribution functions with accurate action estimates for the Galactic disc
H. Al Kazwini, Q. Agobert, A. Siebert +8
In the Gaia era, understanding the effects of the perturbations of the Galactic disc is of major importance in the context of dynamical modelling. In this theoretical paper we exte…
The StEllar Counterparts of COmpact high velocity clouds (SECCO) survey. II. Sensitivity of the survey and an Atlas of Synthetic Dwarf Galaxies
G. Beccari, M. Bellazzini, G. Battaglia +5
SECCO is a survey devoted to the search for stellar counterparts within Ultra Compact High Velocity Clouds. In this contribution we present the results of a set of simulations aime…
Exploring the outskirts of globular clusters: the peculiar kinematics of NGC 3201
P. Bianchini, R. Ibata, B. Famaey
The outskirts of globular clusters (GCs) simultaneously retain crucial information about their formation mechanism and the properties of their host galaxy. Thanks to the advent of…
Why the Northern Hemisphere Needs a 30-40 m Telescope and the Science at Stake: Resolved Stellar Populations Studies in M31 and its Satellites
C. Gallart, E. Fernández-Alvar, A. B. A. Queiroz +48
A 30 m class optical/near-IR telescope in the Northern Hemisphere, equipped for diffraction-limited imaging and high-resolution, multi-object spectroscopy of faint stars, would ena…
Chemical abundances in the nucleus of the Sagittarius dwarf spheroidal galaxy
A. Mucciarelli, M. Bellazzini, R. Ibata +3
We present Iron, Magnesium, Calcium, and Titanium abundances for 235 stars in the central region of the Sagittarius dwarf spheroidal galaxy (within 9.0 arcmin ~70 pc from the cente…
News from the Galactic suburbia: the chemical composition of the remote globular cluster NGC 2419
A. Mucciarelli, M. Bellazzini, R. Ibata +4
We present the chemical analysis of 49 giant stars of the globular cluster NGC 2419, using medium resolution spectra collected with the multi-object spectrograph DEIMOS@Keck. Previ…
Metallicity and mean age across M33
M. -R. L. Cioni, M. Irwin, A. M. N. Ferguson +6
New wide-field near-infrared (NIR) imaging observations of M33 were obtained from UKIRT. These show a large population of intermediate-age stars considerably improving on previous…
Science Case and Requirements for the MOSAIC Concept for a Multi-Object Spectrograph for the European Extremely Large Telescope
C. J. Evans, M. Puech, B. Barbuy +55
Over the past 18 months we have revisited the science requirements for a multi-object spectrograph (MOS) for the European Extremely Large Telescope (E-ELT). These efforts span the…
The Haunted Halos of Andromeda and Triangulum: A panorama of galaxy formation in action
R. Ibata, N. F. Martin, M. Irwin +4
We present a deep photometric survey of M31, conducted with the CFHT and INT, covering the inner 50 kpc of the galaxy, the Southern quadrant out to 150 kpc, and extending to M33. T…
A faint extended cluster in the outskirts of NGC 5128: evidence of a low mass accretion
M. Mouhcine, W. E. Harris, R. Ibata +1
We report the discovery of an extended globular cluster in a halo field in Centaurus A (NGC 5128), situated $\sim 38\kpc$ from the centre of that galaxy, imaged with the Advanced C…
Re-examination of the possible tidal stream in front of the LMC
R. Ibata, G. Lewis, J. -P. Beaulieu
It has recently been suggested that the stars in a vertical extension of the red clump feature seen in LMC color-magnitude diagrams could belong to a tidal stream of material locat…
MOONS Surveys of the Milky Way and its Satellites
O. A. Gonzalez, A. Mucciarelli, L. Origlia +37
The study of resolved stellar populations in the Milky Way and other Local Group galaxies can provide us with a fossil record of their chemo-dynamical and star-formation histories…
A panoramic view of the Milky Way analogue NGC 891
M. Mouhcine, R. Ibata, M. Rejkuba
Recent panoramic observations of the dominant spiral galaxies of the Local Group have revolutionized our view of how these galaxies assemble their mass. However, it remains complet…
Detection of the Canis Major galaxy at (l;b)=(244;-8) and in the background of Galactic open clusters
M. Bellazzini, R. Ibata, L. Monaco +3
We report on the detection of Main Sequence stars belonging to the recently identified Canis Major galaxy in a field located at ~ 4.2 deg from the center of the stellar system. Wit…
ARGOS IV: The Kinematics of the Milky Way Bulge
M. Ness, K. Freeman, E. Athanassoula +8
We present the kinematic results from our ARGOS spectroscopic survey of the Galactic bulge of the Milky Way. Our aim is to understand the formation of the Galactic bulge. We examin…
The outer halo globular cluster system of M31 - I. The final PAndAS catalogue
A. P. Huxor, A. D. Mackey, A. M. N. Ferguson +8
We report the discovery of 59 globular clusters (GCs) and two candidate GCs in a search of the halo of M31, primarily via visual inspection of CHFT/MegaCam imagery from the Pan-And…
The unexpected kinematics of multiple populations in NGC6362: do binaries play a role?
E. Dalessandro, A. Mucciarelli, M. Bellazzini +9
We present a detailed analysis of the kinematic properties of the multiple populations (MPs) in the low-mass Galactic globular cluster NGC6362 based on a sample of about 500 member…
AGB stars as tracers of metallicity and mean age across M33
M. -R. L. Cioni, M. Irwin, A. M. N. Ferguson +6
Wide-field JHKs near-infrared observations covering an area of 1.8x1.8 sq. deg. centred on M33 were obtained using WFCAM at UKIRT. These data show a large population of intermediat…
The structure of star clusters in the outer halo of M31
N. R. Tanvir, A. D. Mackey, A. M. N. Ferguson +11
We present a structural analysis of halo star clusters in M31 based on deep Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) imaging. The clusters in our sample span…
The Sagittarius stream in Gaia eDR3 and the origin of the bifurcations
P. Ramos, T. Antoja, Z. Yuan +6
The Sagittarius dwarf spheroidal (Sgr) is a dissolving galaxy being tidally disrupted by the Milky Way (MW). Its stellar stream still poses serious modelling challenges, which hind…
ARGOS II: The Galactic Bulge Survey
K. Freeman, M. Ness, E. Wylie de Boer +8
We describe the motivation, field locations and stellar selection for the ARGOS spectroscopic survey of 28,000 stars in the bulge and inner disk of the Milky Way galaxy across lati…
The Star Formation History in The Far Outer Disc of M33
M. K. Barker, A. M. N. Ferguson, A. A. Cole +5
The outer regions of disc galaxies are becoming increasingly recognized as key testing sites for models of disc assembly and evolution. Important issues are the epoch at which the…
A very dark stellar system lost in Virgo: kinematics and metallicity of SECCO1 with MUSE
G. Beccari, M. Bellazzini, L. Magrini +11
We present the results of VLT-MUSE integral field spectroscopy of SECCO1, a faint, star-forming stellar system recently discovered as the stellar counterpart of an Ultra Compact Hi…
A non-axisymmetric potential for the Milky Way disk
Y. R. Khalil, B. Famaey, G. Monari +9
We provide a purely dynamical global map of the non-axisymmetric structure of the Milky Way disk. For this, we exploit the information contained within the in-plane motions of disk…
Euclid. I. Overview of the Euclid mission
Euclid Collaboration, Y. Mellier, Abdurro'uf +1134
The current standard model of cosmology successfully describes a variety of measurements, but the nature of its main ingredients, dark matter and dark energy, remains unknown. Eucl…
Chemical and kinematical properties of Galactic bulge stars surrounding the stellar system Terzan 5
Davide Massari, A. Mucciarelli, F. R. Ferraro +8
As part of a study aimed at determining the kinematical and chemical properties of Terzan 5, we present the first characterization of the bulge stars surrounding this puzzling stel…
Tracing the stellar component of low surface brightness Milky Way Dwarf Galaxies to their outskirts I: Sextans
L. Cicuendez, G. Battaglia, M. Irwin +12
We present results from deep and very spatially extended CTIO/DECam and photometry (reaching out to 2 mag below the oldest MSTO and covering 20 deg) aroun…
A new population of extended, luminous star clusters in the halo of M31
A. P. Huxor, N. R. Tanvir, M. J. Irwin +5
We present three new clusters discovered in the halo of M31 which, although having globular-like colours and luminosities,have an unusually large half-light radii, ~30 pc. They lie…
The tidal trail of NGC205?
A. McConnachie, M. Irwin, G. Lewis +4
Using data taken as part of the Isaac Newton Telescope Wide Field Camera (INT WFC) survey of M31, we have identified an arc-like overdensity of blue, presumably metal-poor, red gia…
Tracing the Sgr Stream with 2MASS. Detection of Stream stars around Outer Halo Globular Clusters
M. Bellazzini, R. Ibata, F. R. Ferraro +1
We use infrared Color Magnitude Diagrams from the 2-Micron All-Sky Survey (2MASS) to search for stars belonging to the tidal stream of the Sagittarius dwarf spheroidal galaxy (Sgr…
Sailing on the Sagittarius Stream with Gaia DR2. I. The globular cluster NGC5634
M. Bellazzini, R. Ibata
We use Gaia DR2 data to show that the globular cluster NGC5634 is physically associated with an arm of the Sagittarius Stream, the huge system of tidal tails created by the ongoing…
Do submillimeter galaxies really trace the most massive dark matter halos? Discovery of a high-z cluster in a highly active phase of evolution
S. C. Chapman, A. W. Blain, R. Ibata +3
We present detailed observations of a z~1.99 cluster of submillimeter galaxies (SMGs), discovered as the strongest redshift spike in our entire survey of ~100 SMGs across 800 squar…
Selecting Sagittarius: Identification and Chemical Characterization of the Sagittarius Stream
E. A. Hyde, S. Keller, D. B. Zucker +11
Wrapping around the Milky Way, the Sagittarius stream is the dominant substructure in the halo. Our statistical selection method has allowed us to identify 106 highly likely member…
An active M8.5 dwarf wide companion to the M4/DA binary LHS4039/LHS4040
R. -D. Scholz, N. Lodieu, R. Ibata +4
Low-mass and brown dwarfs have recently been found as wide companions to many nearby stars, formerly believed to be single. Wide binaries are usually found as common proper motion…
Tracing Hercules in Galactic azimuth with Gaia DR2
G. Monari, B. Famaey, A. Siebert +4
The second data release of the Gaia mission has revealed, in stellar velocity and action space, multiple ridges, the exact origin of which is still debated. Recently, we demonstrat…
Detection of massive tidal tails around the globular cluster Pal 5 with SDSS commissioning data
M. Odenkirchen, E. K. Grebel, C. M. Rockosi +17
We report the discovery of two well-defined tidal tails emerging from the sparse remote globular cluster Palomar 5. These tails stretch out symmetrically to both sides of the clust…
ACS photometry of extended, luminous globular clusters in the outskirts of M31
A. D. Mackey, A. Huxor, A. M. N. Ferguson +6
A new population of extended, luminous globular clusters has recently been discovered in the outskirts of M31. These objects have luminosities typical of classical globular cluster…
The Discovery of Remote Globular Clusters in M33
A. Huxor, A. M. N. Ferguson, M. K. Barker +5
We present the discovery of four remote star clusters in M33, one of which is of an extended nature. Three of the clusters were discovered using survey data from the Isaac Newton T…
A Pristine-UNIONS view on the Galaxy: Kinematics of the distant spur feature of the Sagittarius stream traced by Blue Horizontal Branch stars
M. Bayer, E. Starkenburg, G. F. Thomas +14
Providing a detailed picture of the Sagittarius (Sgr) stream offers important constraints on the build-up of the Galactic halo as well as its gravitational potential at large radii…
Density and kinematic cusps in M54 at the heart of the Sagittarius dwarf galaxy: evidence for a 10^4 M_sun Black Hole?
R. Ibata, M. Bellazzini, S. C. Chapman +8
We report the detection of a stellar density cusp and a velocity dispersion increase in the center of the globular cluster M54, located at the center of the Sagittarius dwarf galax…
HII regions within a compact high velocity cloud. A nearly star-less dwarf galaxy?
M. Bellazzini, L. Magrini, A. Mucciarelli +9
Within the SECCO survey we identified a candidate stellar counterpart to the Ultra Compact High Velocity Cloud (UCHVC) HVC274.68+74.70-123, that was suggested by Adams et al. (2013…
The flaring HI disk of the nearby spiral galaxy NGC 2683
B. Vollmer, F. Nehlig, R. Ibata
New deep VLA D array HI observations of the highly inclined nearby spiral galaxy NGC 2683 are presented. Archival C array data were processed and added to the new observations. To…
Masses of the components of SB2 binaries observed with Gaia. IV. Accurate SB2 orbits for 14 binaries, and masses of 3 binaries
F. Kiefer, J. -L. Halbwachs, Y. Lebreton +7
The orbital motion of non-contact double-lined spectroscopic binaries (SB2), with periods of a few tens of days to several years, holds unique accurate informations on individual s…
The globular cluster NGC 2419: a crucible for theories of gravity
R. Ibata, A. Sollima, C. Nipoti +3
We present the analysis of a kinematic data set of stars in the globular cluster NGC 2419, taken with Keck/DEIMOS. Combined with a reanalysis of deep HST and Subaru imaging data, w…
Globular Cluster Candidates in NGC 891
W. E. Harris, M. Mouhcine, M. Rejkuba +1
We use deep images taken with the Advanced Camera for Surveys on board the Hubble Space Telescope of the disk galaxy NGC 891, to search for globular cluster candidates. This galaxy…
ACS photometry of newly-discovered globular clusters in the outer halo of M31
A. D. Mackey, A. Huxor, A. M. N. Ferguson +6
We report the first results from deep ACS imaging of ten classical globular clusters in the far outer regions (15 < R_p < 100 kpc) of M31. Eight of the clusters, including two of t…
A panoramic view of M81: New stellar systems in the debris field
M. Mouhcine, R. Ibata
Using the MegaCam imager on the Canada-France-Hawaii Telescope, we have resolved individual stars in the outskirts of the nearby large spiral galaxy M81 (NGC 3031) well below the t…
Chemical abundances of giant stars in NGC 5053 and NGC 5634, two globular clusters associated with the Sagittarius dwarf Spheroidal galaxy?
L. Sbordone, L. Monaco, C. Moni Bidin +8
The tidal disruption of the Sagittarius dwarf Spheroidal galaxy (Sgr dSph) is producing the most prominent substructure in the Milky Way (MW) halo, the Sagittarius Stream. Aside fr…
Taking measure of the Andromeda halo: a kinematic analysis of the giant stream surrounding M31
R. Ibata, S. Chapman, A. M. N. Ferguson +3
We present a spectroscopic survey of the giant stellar stream found in the halo of the Andromeda galaxy. Taken with the DEIMOS multi-object spectrograph on the Keck2 telescope, the…
The kinematic footprints of five stellar streams in Andromeda's halo
S. C. Chapman, R. Ibata, M. Irwin +12
(abridged) We present a spectroscopic analysis of five stellar streams (`A', `B', `Cr', `Cp' and `D') as well as the extended star cluster, EC4, which lies within streamC, all disc…
Globular Clusters in the Sagittarius stream. Revising members and candidates with Gaia DR2
M. Bellazzini, R. Ibata, K. Malhan +3
We reconsider the case for the association of Galactic globular clusters (GCs) to the tidal stream of the Sagittarius dwarf spheroidal galaxy (Sgr dSph), using Gaia DR2 data. We us…
Probing the radial acceleration relation and the strong equivalence principle with the Coma cluster ultra-diffuse galaxies
J. Freundlich, B. Famaey, P. -A. Oria +3
The tight radial acceleration relation (RAR) obeyed by rotationally supported disk galaxies is one of the most successful a priori predictions of the modified Newtonian dynamics (M…
The origin of the split red clump in the Galactic bulge of the Milky Way
M. Ness, K. Freeman, E. Athanassoula +8
Near the minor axis of the Galactic bulge, at latitudes b < -5 degrees, the red giant clump stars are split into two components along the line of sight. We investigate this split u…
A new wide pair of cool white dwarfs in the Solar neighbourhood
R. -D. Scholz, G. P. Szokoly, M. Andersen +2
We report the discovery of a wide pair (93 arcsec angular separation) of extremely cool ( K) white dwarfs with a very large common proper motion ( arcsec/yr)…
On the accretion origin of a vast extended stellar disk around the Andromeda galaxy
R. Ibata, S. Chapman, A. M. N. Ferguson +3
We present the discovery of an inhomogenous, low-surface brightness, extended disk-like structure around the Andromeda galaxy (M31) based on a large kinematic survey of more than 2…
Potassium: a new actor on the globular cluster chemical evolution stage. The case of NGC 2808
A. Mucciarelli, M. Bellazzini, T. Merle +3
We derive [K/Fe] abundance ratios for 119 stars in the globular cluster NGC 2808, all of them having O, Na, Mg and Al abundances homogeneously measured in previous works. We detect…
The core of the Canis Major galaxy as traced by Red Clump stars
M. Bellazzini, R. Ibata, N. Martin +3
The recently-discovered stellar system in Canis Major is analysed using He-burning Red Clump stars as tracers. Canis Major turns out to be the strongest and most spatially confined…
The Luminosity Function and stellar Mass to Light ratio of the massive globular cluster NGC2419
M. Bellazzini, E. Dalessandro, A. Sollima +1
We used archival Hubble Space Telescope WFC3 images to obtain the Luminosity Function of the remote globular cluster NGC2419 from two magnitudes above the Horizontal Branch level d…
A 2-3 billion year old major merger paradigm for the Andromeda galaxy and its outskirts
F. Hammer, Y. B. Yang, J. L. Wang +3
Recent observations of our neighbouring galaxy M31 have revealed that its disk was shaped by widespread events. The evidence for this includes the high dispersion ( 3)…
Are small-scale sub-structures a universal property of galaxy halos? The case of the giant elliptical NGC~5128
M. Mouhcine, R. Ibata, M. Rejkuba
We present an analysis of the spatial and chemical sub-structures in a remote halo field in the nearby giant elliptical galaxy Centaurus A (NGC~5128), situated at about 38 kpc from…
The StEllar Counterparts of COmpact high velocity clouds (SECCO) survey. I. Photos of ghosts
M. Bellazzini, G. Beccari, G. Battaglia +6
We present an imaging survey aimed at searching for the stellar counterparts of recently discovered ultra-compact high-velocity HI clouds (UCHVC). Adams et al. (2013) proposed thes…
The phantom dark matter halos of the Local Volume in the context of modified Newtonian dynamics
P. -A. Oria, B. Famaey, G. F. Thomas +8
We explore the predictions of Milgromian gravity (MOND) in the Local Universe by considering the distribution of the `phantom' dark matter (PDM) that would source the MOND gravitat…
Globular Clusters in the Sgr Stream and other structures
M. Bellazzini, R. Ibata, F. R Ferraro
The possible association of Galactic globular clusters with the Sgr Stream is shortly reviewed at the light of the most recent observations of the Stream. >= 20 % of the Galactic g…
Newly Discovered Globular Clusters in the Outer Halo of M31
A. Huxor, N. R. Tanvir, M. Irwin +4
We present nine newly discovered globular clusters in the outer halo of M31, found by a semi-automated procedure from a INT Wide Field Camera survey of the region. The sample inclu…
Globular clusters in the outer halo of M31: the survey
A. P. Huxor, N. R. Tanvir, A. M. N. Ferguson +4
We report the discovery of 40 new globular clusters (GCs) that have been found in surveys of the halo of M31 based on INT/WFC and CHFT/Megacam imagery. A subset of these these new…
The Gaia RVS benchmark stars II. A sample of stars selected for their Gaia high radial velocity
E. Caffau, D. Katz, A. Gómez +16
The Gaia satellite has already provided the astronomical community with three data releases, and the Radial Velocity Spectrometer (RVS) on board Gaia has provided the radial veloci…
A new method based on Markov chains for deriving SB2 orbits directly from their spectra
J. -B. Salomon, R. Ibata, P. Guillout +7
We present a new method to derive orbital elements of double-lined spectroscopic binaries (SB2). The aim is to have accurate orbital parameters of a selection of SB2 in order to pr…
The Hubble Space Telescope Survey of M31 Satellite Galaxies II. The Star Formation Histories of Ultra-Faint Dwarf Galaxies
A. Savino, D. R. Weisz, E. D. Skillman +34
We present the lifetime star formation histories (SFHs) for six ultra-faint dwarf (UFD; , ) satellite galaxies of M31 based on…
Alone on a wide wide sea. The origin of SECCO 1, an isolated star-forming gas cloud in the Virgo cluster
M. Bellazzini, L. Armillotta, S. Perina +12
SECCO1 is an extremely dark, low-mass (M_star=10^5 M_sun), star-forming stellar system lying in the Low Velocity Cloud (LVC) substructure of the Virgo cluster of galaxies, and host…
The proper motion of Andromeda from Gaia eDR3: confirming a nearly radial orbit
J. -B. Salomon, R. Ibata, C. Reylé +4
We present an analysis of the proper motion of the Andromeda galaxy (M31), based on the Early Third Data Release of the Gaia mission. We use the Gaia photometry to select young blu…
The Hubble Space Telescope Survey of M31 Satellite Galaxies IV. Survey Overview and Lifetime Star Formation Histories
A. Savino, D. R. Weisz, A. E. Dolphin +35
From orbits of HST imaging, we present deep homogeneous resolved star color-magnitude diagrams that reach the oldest main sequence turnoff and uniformly measured star forma…
Strangers in the night: Discovery of a dwarf spheroidal galaxy on its first Local Group infall
S. C. Chapman, J. Penarrubia, R. Ibata +9
We present spectroscopic observations of the AndXII dwarf spheroidal galaxy using DEIMOS/Keck-II, showing it to be moving rapidly through the Local Group (-556 km/s heliocentric ve…
At the survey limits: discovery of the Aquarius 2 dwarf galaxy in the VST ATLAS and the SDSS data
G. Torrealba, S. E. Koposov, V. Belokurov +7
We announce the discovery of the Aquarius~2 dwarf galaxy, a new distant satellite of the Milky Way, detected on the fringes of the VST ATLAS and the SDSS surveys. The object was or…
A kinematically selected, metal-poor stellar halo in the outskirts of M31
S. C. Chapman, R. Ibata, G. F. Lewis +4
We present evidence for a metal-poor, [Fe/H] =0.2 dex, stellar halo component detectable at radii from 10 kpc to 70 kpc, in our nearest giant spiral neighbor, the And…
A spectroscopic survey of EC4, an Extended Cluster in Andromeda's halo
M. L. M. Collins, S. C. Chapman, M. Irwin +8
We present a spectroscopic survey of candidate red giant branch stars in the extended star cluster, EC4, discovered in the halo of M31 from our CFHT/MegaCam survey, overlapping the…
Spectroscopic classification of red high proper motion objects in the Southern Sky
N. Lodieu, R. -D. Scholz, M. J. McCaughrean +3
We present the results of spectroscopic follow-up observations for a sample of 71 red objects with high proper motions in the range 0.08-1.14 arcsec/yr as detected using APM and SS…
PLATO as it is: a legacy mission for Galactic archaeology
A. Miglio, C. Chiappini, B. Mosser +102
Deciphering the assembly history of the Milky Way is a formidable task, which becomes possible only if one can produce high-resolution chrono-chemo-kinematical maps of the Galaxy.…
The Pristine survey. XXVI. Chemical abundances of subgiant stars of the extremelymetal-poor stream C-19
P. Bonifacio, E. Caffau, P. François +17
Context: The C-19 stellar stream is the most metal-poor stream known to date. While its width and velocity dispersion indicate a dwarf galaxy origin, its metallicity spread and abu…