Publications (143)
The Optical Polarisation of the Vela Pulsar revisited
R. P. Mignani, S. Bagnulo, J. Dyks +2
In this work we present a revised measurement of the phase-averaged optical polarisation of the Vela pulsar (PSR B0833-45), for which only one value has been published so far (Wagn…
Broadband linear polarization and modelling of magnetic fields in CP stars
S. Bagnulo
The observations in broadband linear polarization (BBLP) represent a powerful diagnostic tool for detecting the magnetic morphology of CP stars. In several cases, BBLP observations…
Measurements of magnetic fields over the pulsation cycle in six roAp stars with FORS1 at the VLT
S. Hubrig, D. W. Kurtz, S. Bagnulo +4
With FORS1 at the VLT we have tried for the first time to measure the magnetic field variation over the pulsation cycle in six roAp stars to begin the study of how the magnetic fie…
Constraints on interstellar dust models from extinction and spectro-polarimetry
R. Siebenmorgen, N. V. Voshchinnikov, S. Bagnulo +1
We present polarisation spectra of seven stars in the lines-of-sight towards the Sco OB1 association. Our spectra were obtained within the framework of the Large Interstellar Polar…
Studies of Neutron Stars at Optical/IR Wavelengths
R. P. Mignani, S. Bagnulo, A. De Luca +7
In the last years, optical studies of Isolated Neutron Stars (INSs) have expanded from the more classical rotation-powered ones to other categories, like the Anomalous X-ray Pulsar…
Rotation and chemical abundances of Ap/Bp stars in the open cluster NGC 6475
C. P. Folsom, G. A. Wade, S. Bagnulo +1
The connection between age, rotation and chemical abundance of magnetic Ap stars is poorly understood. Using open clusters, we are able to study samples of stars that are both co-e…
The spectral variability and magnetic field characteristics of the Of?p star HD 148937
G. A. Wade, J. Grunhut, G. Graefener +11
We report magnetic and spectroscopic observations and modeling of the Of?p star HD 148937 within the context of the MiMeS LP at the CFHT. Thirty-two high signal-to-noise ratio circ…
Photometry and polarimetry of the nucleus of comet 2P/Encke
H. Boehnhardt, G. P. Tozzi, S. Bagnulo +3
Broadband imaging photometry, and broadband and narrowband linear polarimetry was measured for the nucleus of 2P/Encke over the phase-angle range 4 - 28 deg. An analysis of the poi…
A search for magnetic fields in the variable HgMn star Andromedae
G. A. Wade, M. Auriere, S. Bagnulo +8
With this work, we have conducted an extensive search for magnetic fields in the photosphere of ~And. We have acquired new circular polarisation spectra with the MuSiCoS and ES…
Magnetic Field and Atmospheric Chemical Abundances of the Magnetic Ap Star HD 318107
J. D. Bailey, J. D. Landstreet, S. Bagnulo +5
New spectra have been obtained with the ESPaDOnS spectropolarimeter supplemented with unpolarised spectra from the ESO UVES, UVES-FLAMES, and HARPS spectrographs of the very peculi…
Linear spectro-polarimetry: a new diagnostic tool for the classification and characterisation of asteroids
S. Bagnulo, A. Cellino, M. Sterzik
We explore the use of spectro-polarimetry as a remote sensing tool for asteroids in addition to traditional reflectance measurements. In particular we are interested in possible re…
Rare-earth elements in the atmosphere of the magnetic chemically peculiar star HD 144897. New classification of the Nd III spectrum
T. Ryabchikova, A. Ryabtsev, O. Kochukhov +1
We have obtained a UVES spectrum of a slowly rotating strongly magnetic Ap star, HD 144897, that exhibits very large overabundances of rare-earth elements. Here we present a detail…
A search for strong magnetic fields in massive and very massive stars in the Magellanic Clouds
S. Bagnulo, G. A. Wade, Y. Naze +13
Despite their rarity, massive stars dominate the ecology of galaxies via their strong, radiatively-driven winds throughout their lives and as supernovae in their deaths. However, t…
Searching for links between magnetic fields and stellar evolution III. Measurement of magnetic fields in open cluster Ap stars with ESPaDOnS
J. D. Landstreet, J. Silaj, V. Andretta +7
We are carrying out a survey of magnetic fields in Ap stars in open clusters in order to obtain the first sample of magnetic upper main sequence stars with precisely known ages. Th…
Isotopic anomaly and stratification of Ca in magnetic Ap stars
T. Ryabchikova, O. Kochukhov, S. Bagnulo
We have carried out an accurate investigation of the Ca isotopic composition and stratification in the atmospheres of 23 magnetic chemically peculiar (Ap) stars of different temper…
Polarimetry of the dwarf planet (136199) Eris
I. Belskaya, S. Bagnulo, K. Muinonen +4
We investigate the surface characteristics of the large dwarf planet (136199) Eris. With the FORS1 instrument of the ESO VLT, we have obtained Bessell broadband R linear polarimetr…
Pulsations in the atmosphere of the rapidly oscillating Ap star 10 Aquilae
M. Sachkov, O. Kochukhov, T. Ryabchikova +4
The rapidly oscillating Ap (roAp) star 10 Aql shows one of the lowest photometric pulsation amplitudes and is characterized by an unusual spectroscopic pulsational behavior compare…
Magnetic field, chemical composition and line profile variability of the peculiar eclipsing binary star AR Aur
C. P. Folsom, O. Kochukhov, G. A. Wade +2
AR Aur is the only eclipsing binary known to contain a HgMn star, making it an ideal case for a detailed study of the HgMn phenomenon. HgMn stars are a poorly understood class of c…
VSTPOL: making the VST a large survey telescope for optical polarimetry
P. Schipani, S. Covino, F. Snik +30
Since the start of operations in 2011, the VLT Survey Telescope (VST) has been one of the most efficient wide-field imagers in the optical bands. However, in the next years the Ver…
Spectroscopic study of pulsations in the atmosphere of roAp star 10 Aql
M. Sachkov, O. Kochukhov, T. Ryabchikova +3
We present the analysis of spectroscopic time-series observations of the roAp star 10 Aql. Observations were carried out in July 2006 with the UVES and SARG spectrographs simultane…
Dust observations of Comet 9P/Tempel 1 at the time of the Deep Impact
G. P. Tozzi, H. Boehnhardt, L. Kolokolova +15
On 4 July 2005 at 05:52 UT, the impactor of NASA's Deep Impact (DI) mission crashed into comet 9P/Tempel 1 with a velocity of about 10 km/s. The material ejected by the impact expa…
The effect of rotation on the abundances of the chemical elements of the A-type stars in the Praesepe cluster
L. Fossati, S. Bagnulo, J. Landstreet +5
We study how chemical abundances of late B-, A- and early F-type stars evolve with time, and we search for correlations between the abundance of chemical elements and other stellar…
Discovery of six new strongly magnetic white dwarfs in the 20 pc local population
S. Bagnulo, J. D. Landstreet
The sample of white dwarfs included in the local 20 pc volume documents, fairly accurately, the total production of white dwarfs over roughly 10 Gyr of stellar evolution in this pa…
Searching for links between magnetic fields and stellar evolution. II. The evolution of magnetic fields as revealed by observations of Ap stars in open clusters and associations
J. D. Landstreet, S. Bagnulo, V. Andretta +4
The evolution of magnetic fields in Ap stars during the main sequence phase is presently mostly unconstrained by observation because of the difficulty of assigning accurate ages to…
Chemical peculiarities in magnetic and non-magnetic pre-main sequence A and B stars
C. P. Folsom, S. Bagnulo, G. A. Wade +2
In A- and late B-type stars, strong magnetic fields are always associated with Ap and Bp chemical peculiarities. However, it is not clear at what point in a star's evolution those…
A search of very low amplitude magnetoacoustic pulsations with HARPS
O. Kochukhov, T. Ryabchikova, S. Bagnulo +1
We have obtained time-resolved spectroscopic observations for a sample of 10 cool Ap stars using the ultra-stable spectrograph HARPS at the ESO 3.6-m telescope. The aim of our stud…
Magnetic fields in Herbig Ae/Be stars
G. A. Wade, C. Catala, E. Alecian +7
Studies of stellar magnetism at the pre-main sequence phase can provide important new insights into the detailed physics of the late stages of star formation, and into the observed…
Investigating the pre-main sequence magnetic chemically peculiar system HD 72106
C. P. Folsom, G. A. Wade, D. A. Hanes +7
The origin of the strong magnetic fields observed in chemically peculiar Ap and Bp stars stars has long been debated. The recent discovery of magnetic fields in the intermediate ma…
New insight into the magnetism of degenerate stars from the analysis of a volume limited sample of white dwarfs
S. Bagnulo, J. D. Landstreet
Many stars evolve into magnetic white dwarfs, and observations may help to understand when the magnetic field appears at the stellar surface, if and how it evolves during the cooli…
Magnetic field measurements and their uncertainties: the FORS1 legacy
S. Bagnulo, J. D. Landstreet, L. Fossati +1
During the last decade, the FORS1 instrument of the ESO VLT has been extensively used to study stellar magnetism. A number of interesting discoveries of magnetic fields in several…
Magnetic, Chemical and Rotational Properties of the Herbig Ae/Be Binary System HD 72106
C. P. Folsom, G. A. Wade, O. Kochukhov +5
Recently, strong, globally-ordered magnetic fields have been detected in some Herbig Ae and Be (HAeBe) stars, suggesting a possible evolutionary connection to main sequence magneti…
Discovery of a Sirius-like binary system with a very strongly magnetic white dwarf. Binarity among magnetic white dwarfs
J. D. Landstreet, S. Bagnulo
Binary systems containing a magnetic white dwarf and a main-sequence star are considered extremely rare, perhaps non-existent. In the course of a search of magnetic fields in high-…
Strong magnetic fields of old white dwarfs are symmetric about the stellar rotation axes
S. Bagnulo, J. D. Landstreet
Many magnetic white dwarfs exhibit a polarised spectrum that periodically varies as the star rotates because the magnetic field is not symmetric about the rotation axis. In this wo…
Discovery of the pre-main sequence progenitors of the magnetic Ap/Bp stars?
G. A. Wade, D. Drouin, S. Bagnulo +8
We report the discovery, using FORS1 at the ESO-VLT and ESPaDOnS at the CFHT, of magnetic fields in the young A-type stars HD 101412, V380 Ori and HD 72106A. Two of these stars (HD…
A polarimetric study of asteroids: Fitting phase - polarization curves
A. Cellino, S. Bagnulo, R. Gil-Hutton +3
By considering all asteroid linear polarization data available in the literature, it is possible to obtain updated phase - polarization curves for several tens of objects. In a sep…
Searching for magnetic fields in featureless white dwarfs with the DIPOL-UF polarimeter at the Nordic Optical Telescope
A. Berdyugin, J. D. Landstreet, S. Bagnulo +2
About 20% of the white dwarfs possess a magnetic field that may be detected by the splitting and/or polarization of their spectral lines. As they cool, the effective temperatures o…
Multi-wavelength Study of IRAS 19254-7245 - The Superantennae
L. Vanzi, S. Bagnulo, E. Le Floc'h +3
We present observations in the optical, near-infrared and millimetre bands of the Ultraluminous Infrared galaxy IRAS 19254-7245, also known as "The Superantennae". This galaxy is a…
The FORS1 catalogue of stellar magnetic field measurements
S. Bagnulo, L. Fossati, J. D. Landstreet +1
The FORS1 instrument on the ESO Very Large Telescope was used to obtain low-resolution circular polarised spectra of nearly a thousand different stars, with the aim of measuring th…
Stokes IQUV Magnetic Doppler Imaging of Ap stars I. ESPaDOnS and NARVAL Observations
J. Silvester, G. A. Wade, O. Kochukhov +3
In this paper we describe and evaluate new spectral line polarisation observations obtained with the goal of mapping the surfaces of magnetic Ap stars in great detail. One hundred…
On the calibration of the relation between geometric albedo and polarimetric properties for the asteroids
A. Cellino, S. Bagnulo, R. Gil-Hutton +3
We present a new extensive analysis of the old problem of finding a satisfactory calibration of the relation between the geometric albedo and some measurable polarization propertie…
Standard stars for linear polarization
L. Fossati, S. Bagnulo, E. Mason +1
We present the analysis of the observations of standard stars for linear polarization obtained from 1999 to 2005 within the context of the calibration plan of the FORS1 instrument…
NGC 6611 601: A hot pre-main sequence spectroscopic binary containing a centrifugal magnetosphere host star
M. E. Shultz, E. Alecian, V. Petit +5
W 601 (NGC 6611 601) is one of the handful of known magnetic Herbig Ae/Be stars. We report the analysis of a large dataset of high-resolution spectropolarimetry. The star is a prev…
Magnetism in Herbig Ae/Be stars and the link to the Ap/Bp stars
E. Alecian, C. Catala, G. A. Wade +11
Among the A/B stars, about 5% host large-scale organised magnetic fields. These magnetic stars show also abundance anomalies in their spectra, and are therefore called the magnetic…
HD 178892 - a cool Ap star with extremely strong magnetic field
T. Ryabchikova, O. Kochukhov, D. Kudryavtsev +6
We report a discovery of the Zeeman resolved spectral lines, corresponding to the extremely large magnetic field modulus <Bs>=17.5 kG, in the cool Ap star HD 178892. The mean longi…
Unusual polarimetric properties of (101955) Bennu: similarities with F-class asteroids and cometary bodies
A. Cellino, S. Bagnulo, I. N. Belskaya +1
We have obtained polarimetric measurements of asteroid (101955) Bennu, a presumably primitive near-Earth object (NEO) that is the target of NASA's sample return mission OSIRIS-REx.…
A search for strong, ordered magnetic fields in Herbig Ae/Be stars
G. A. Wade, S. Bagnulo, D. Drouin +2
The origin of magnetic fields in intermediate-mass and high-mass stars is fundamentally a mystery. Clues toward solving this basic astrophysical problem can likely be found at the…
Polarimetry of transneptunian objects (136472) Makemake and (90482) Orcus
I. N. Belskaya, S. Bagnulo, A. Stinson +5
Context. We study the surface properties of transneptunian populations of Solar-system bodies. Aims. We investigate the surface characteristics of the dwarf planet (136472) Makemak…
Broadband Linear Polarization of Jupiter Trojans
S. Bagnulo, I. N. Belskaya, A. Stinson +2
Trojan asteroids orbit in the Lagrange points of the system Sun-planet-asteroid. Their dynamical stability make their physical properties important proxies for the early evolution…
VIMOS total transmission profiles for broad-band filters
S. Mieske, M. Rejkuba, S. Bagnulo +2
VIMOS is a wide-field imager and spectrograph mounted on UT3 at the VLT, whose FOV consists of four 7'x8' quadrants. Here we present the measurements of total transmission profiles…
Discovery of magnetic fields in the very young, massive stars W601 (NGC 6611) and OI 201 (NGC 2244)
E. Alecian, G. A. Wade, C. Catala +8
Context: Recent spectropolarimetric observations of Herbig Ae/Be stars have yielded new arguments in favour of a fossil origin for the magnetic fields of intermediate mass stars. A…
Polarimetry of comets 67P/Churyumov-Gerasimenko, 74P/Smirnova-Chernykh, and 152P/Helin-Lawrence
A. Stinson, S. Bagnulo, G. P. Tozzi +5
Aims. Polarimetric characteristics of comets at large heliocentric distances is a relatively unexplored area; we extend the idea by adding and analysing the data for three Jupiter…
Evolutionary state of magnetic chemically peculiar stars
O. Kochukhov, S. Bagnulo
We present a comprehensive statistical investigation of the evolution of magnetic CP stars, aimed at providing constraints to the theories that deal with the origin of the magnetic…
A comprehensive and critical re-analysis of FORS spectropolarimetric observations: the case of HD92207
L. Fossati, S. Bagnulo, J. D. Landstreet +1
Stellar spectropolarimetry has become extremely popular during the last decade, and has led to major advances in our understanding of stellar magnetic fields and of their impact on…
High-resolution spectropolarimetric observations of hot subdwarfs
P. Petit, V. Van Grootel, S. Bagnulo +3
We report on high-resolution spectropolarimetric observations of the hot subdwarf stars HD 76431 and Feige 66, using the ESPaDOnS echelle spectropolarimeter at CFHT. We compute cro…
A probable pre-main sequence chemically peculiar star in the open cluster Stock 16
M. Netopil, L. Fossati, E. Paunzen +3
We used the Ultraviolet and Visual Echelle Spectrograph of the ESO-Very Large Telescope to obtain a high resolution and high signal-to-noise ratio spectrum of Stock 16-12, an early…
Observing the Earth as an exoplanet with LOUPE, the Lunar Observatory for Unresolved Polarimetry of Earth
T. Karalidi, D. M. Stam, F. Snik +3
The detections of small, rocky exoplanets have surged in recent years and will likely continue to do so. To know whether a rocky exoplanet is habitable, we have to characterise its…
Photospheric magnetic field and surface differential rotation of the FK Com star HD 199178
P. Petit, J. -F. Donati, J. M. Oliveira +11
We present spectropolarimetric observations of the FK Com star HD 199178 obtained between 1998 December and 2003 August at the Telescope Bernard Lyot (Observatoire du Pic du Midi,…
Chemical abundances of magnetic and non-magnetic Herbig Ae/Be stars
C. P. Folsom, S. Bagnulo, G. A. Wade +4
The photospheres of about 10-20% of main sequence A- and B-type stars exhibit a wide range of chemical peculiarities, often associated with the presence of a magnetic field. It is…
The olivine-dominated composition of the Eureka family of Mars Trojan asteroids
G. Borisov, A. Christou, S. Bagnulo +3
We have used the XSHOOTER echelle spectrograph on the European Southern Obseratory (ESO) Very Large Telescope (VLT) to obtain UVB-VIS-NIR (ultraviolet-blue (UVB), visible (VIS) and…
Discovery of magnetically guided metal accretion onto a polluted white dwarf
S. Bagnulo, J. Farihi, J. D. Landstreet +1
Dynamically active planetary systems orbit a significant fraction of white dwarf stars. These stars often exhibit surface metals accreted from debris disks, which are detected thro…
Discovery of weak magnetic fields in four DZ white dwarfs in the local 20pc volume. Implications for the frequency of magnetic fields with cooling age
S. Bagnulo, J. D. Landstreet
We report the discovery of weak magnetic fields in three white dwarfs within the local 20pc volume (WD 0816-310, WD 1009-184, and WD 1532+129), and we confirm the magnetic nature o…
The rapid rotation and complex magnetic field geometry of Vega
P. Petit, F. Lignières, G. A. Wade +9
The recent discovery of a weak surface magnetic field on the normal intermediate-mass star Vega raises the question of the origin of this magnetism in a class of stars that was not…
The 67P/Churyumov-Gerasimenko observation campaign in support of the Rosetta mission
C. Snodgrass, M. F. A'Hearn, F. Aceituno +112
We present a summary of the campaign of remote observations that supported the European Space Agency's Rosetta mission. Telescopes across the globe (and in space) followed comet 67…
Magnetic topologies of the Herbig Ae/Be stars
E. Alecian, G. A. Wade, C. Catala +9
Our recent discoveries of magnetic fields in a small number of Herbig Ae/Be (HAeBe) stars, the evolutionary progenitors of main sequence A/B stars, raise new questions about the or…
Dust in the diffuse interstellar medium: Extinction, emission, linear and circular polarisation
R. Siebenmorgen, N. V. Voshchinnikov, S. Bagnulo
We present a model for the diffuse interstellar dust that explains the observed wavelength-dependence of extinction, emission, linear and circular polarisation of light. The model…
How non-magnetic are "non-magnetic" Herbig Ae/Be stars?
G. A. Wade, E. Alecian, C. Catala +9
Our recent discovery of magnetic fields in a small number of Herbig Ae/Be stars has required that we survey a much larger sample of stars. From our FORS1 and ESPaDOnS surveys, we h…
Discovery of secular variations in the atmospheric abundances of magnetic Ap stars
J. D. Bailey, J. D. Landstreet, S. Bagnulo
The stars of the middle main sequence have relatively quiescent outer layers, and unusual chemical abundance patterns may develop in their atmospheres. The presence of chemical pec…
Magnetism in pre-MS intermediate-mass stars and the fossil field hypothesis
E. Alecian, G. A. Wade, C. Catala +11
Today, one of the greatest challenges concerning the Ap/Bp stars is to understand the origin of their slow rotation and their magnetic fields. The favoured hypothesis for the latte…
Magnetism, rotation and accretion in Herbig Ae-Be stars
E. Alecian, G. A. Wade, C. Catala +7
Studies of stellar magnetism at the pre-main sequence phase can provide important new insights into the detailed physics of the late stages of star formation, and into the observed…
The OmegaWhite survey for short-period variable stars - V. Discovery of an ultracompact hot subdwarf binary with a compact companion in a 44 minute orbit
T. Kupfer, G. Ramsay, J. van Roestel +20
We report the discovery of the ultracompact hot subdwarf (sdOB) binary OW J074106.0-294811.0 with an orbital period of P min, making it the…
A detailed spectropolarimetric analysis of the planet hosting star WASP-12
L. Fossati, S. Bagnulo, A. Elmasli +9
The knowledge of accurate stellar parameters is paramount in several fields of stellar astrophysics, particularly in the study of extrasolar planets, where often the star is the on…
The MiMeS Survey of Magnetism in Massive Stars: Introduction and overview
G. A. Wade, C. Neiner, E. Alecian +47
The MiMeS project is a large-scale, high resolution, sensitive spectropolarimetric investigation of the magnetic properties of O and early B type stars. Initiated in 2008 and compl…
Spectro-polarimetry of the bright side of Saturn's moon Iapetus
C. Ejeta, H. Boehnhardt, S. Bagnulo +1
Measurements of the polarized reflected sunlight from atmosphereless solar system bodies, over a range of phase angles, provide information about the surface structure and composit…
Early-type stars observed in the ESO UVES Paranal Observatory Project: I -- Interstellar Na I UV, Ti II and Ca II K observations
I. Hunter, J. V. Smoker, F. P. Keenan +5
We present an analysis of interstellar Na I (lambda=3302.37Ã , 3302.98Ã ), Ti II (lambda=3383.76Ã ) and Ca II K (lambda=3933.66Ã ) absorption features for 74 sightlines towards O-…
On the incidence of weak magnetic fields in DA white dwarfs
J. D. Landstreet, S. Bagnulo, G. G. Valyavin +4
Context: About 10% of white dwarfs have magnetic fields with strength in the range between about 10^5 and 3x10^8 G. It is not known whether the remaining white dwarfs are not magne…
Modelling the photometric variability of magnetic massive stars with the Analytical Dynamical Magnetosphere model
M. S. Munoz, G. A. Wade, Y. Nazé +3
In this paper, we investigate the photometric variability of magnetic O-type stars. Such stars possess oblique, predominantly dipolar magnetic fields that confine their winds rough…
Weak magnetic fields in Ap/Bp stars: Evidence for a dipole field lower limit and a tentative interpretation of the magnetic dichotomy
M. Auriere, G. A. Wade, J. Silvester +22
We have investigated a sample of 28 well-known spectroscopically-identified magnetic Ap/Bp stars, with weak, poorly-determined or previously undetected magnetic fields, with the ai…
Machine Learning Assisted NEO Discovery and Polarimetric Characterisation with Astronomical Surveys
G. A. Verdoes Kleijn, T. Grobler, S. J. Chong +12
We are a group of over two dozen astronomers, computer scientists, data scientists and digital Big Data research platform experts at 11 universities and research institutes in Sout…
Characterisation of the magnetic field of the Herbig Be star HD 200775
E. Alecian, C. Catala, G. A. Wade +9
After our recent discovery of four magnetic Herbig stars, we have decided to study in detail one of them, HD 200775, to determine if its magnetic topology is similar to that of the…
Investigation of the magnetic field characteristics of Herbig Ae/Be stars: Discovery of the pre-main sequence progenitors of the magnetic Ap/Bp stars
G. A. Wade, D. Drouin, S. Bagnulo +10
We are investigating the magnetic characteristics of pre-main sequence Herbig Ae/Be stars, with the aim of (1) understanding the origin and evolution of magnetism in intermediate-m…
First constraints on the magnetic field strength in extra-Galactic stars: FORS2 observations of Of?p stars in the Magellanic Clouds
S. Bagnulo, Y. Naze, I. D. Howarth +6
Massive O-type stars play a dominant role in our Universe, but many of their properties remain poorly constrained. In the last decade magnetic fields have been detected in all Gala…
Large Interstellar Polarisation Survey II. UV/optical study of cloud-to-cloud variations of dust in the diffuse ISM
R. Siebenmorgen, N. V. Voshchinnikov, S. Bagnulo +3
It is well known that the dust properties of the diffuse interstellar medium exhibit variations towards different sight-lines on a large scale. We have investigated the variability…
A spectroscopic study of the open cluster NGC 6250
A. J. Martin, M. J. Stift, L. Fossati +4
We present the chemical abundance analysis of 19 upper main-sequence stars of the young open cluster NGC 6250 (log t ~ 7.42 yr). This work is part of a project aimed at setting obs…
Exploring the surface properties of Transneptunian Objects and Centaurs with polarimetric FORS1/VLT observations
S. Bagnulo, H. Boehnhardt, K. Muinonen +3
Polarization is a powerful remote-sensing method to investigate solar system bodies. It is an especially sensitive diagnostic tool to reveal physical properties of the bodies whose…
New polarimetric and spectroscopic evidence of anomalous enrichment in spinel-bearing Calcium-Aluminium-rich Inclusions among L-type asteroids
M. Devogèle, P. Tanga, A. Cellino +14
Asteroids can be classified into several groups based on their spectral reflectance. Among these groups, the one belonging to the L-class in the taxonomic classification based on v…
A study of the photometric variability of the peculiar magnetic white dwarf WD1953-011
G. Valyavin, K. Antonyuk, S. Plachinda +14
We present and interpret simultaneous new photometric and spectroscopic observations of the peculiar magnetic white dwarf WD1953-011. The flux in the V-band filter and intensity of…
Is the Wind of the Galactic Oe Star HD 155806 Magnetically Confined?
A. W. Fullerton, V. Petit, S. Bagnulo +2
Spectropolarimetric observations of HD 155806 - the hottest Galactic Oe star - were obtained with CFHT/ESPaDOnS to test the hypothesis that disk signatures in its spectrum are due…
A massive helium star with a sufficiently strong magnetic field to form a magnetar
T. Shenar, G. A. Wade, P. Marchant +13
Magnetars are highly magnetized neutron stars; their formation mechanism is unknown. Hot helium-rich stars with spectra dominated by emission lines are known as Wolf-Rayet stars. W…
Stellar magnetism through the polarized eyes of the FORS1 instrument
S. Bagnulo, J. D. Landstreet, L. Fossati +1
During the last decade, the FORS1 instrument of the ESO Very Large Telescope has been used to obtain low resolution circular polarized spectra for about 500 stars, with the aim of…
Polarimetry and albedo of the Near-Earth Asteroid 2025 FA22
J. -P. Rivet, S. Bagnulo, P. Bendjoya +17
We report spectropolarimetric and broadband polarimetric observations of the near-Earth asteroid 2025 FA22 during its close approach of 18 September 2025 (about two Moon distances)…
Metal accretion scars may be common on magnetic, polluted white dwarfs
S. Bagnulo, J. D. Landstreet, J. Farihi +3
More than 30% of white dwarfs exhibit atmospheric metals, which are understood to be from recent or ongoing accretion of circumstellar debris. In cool white dwarfs, surface motions…
The discovery of high-amplitude 10.9-minute oscillations in the cool magnetic Ap star HD 115226
O. Kochukhov, T. Ryabchikova, S. Bagnulo +1
We present the discovery of pulsational variations in the cool magnetic Ap star HD 115226 -- the first high-amplitude rapidly oscillating Ap star discovered with time-series spectr…
The pecular magnetic field morphology of the white dwarf WD 1953-011: evidence for a large-scale magnetic flux tube?
G. Valyavin, G. A. Wade, S. Bagnulo +4
We present and interpret new spectropolarimetric observations of the magnetic white dwarf WD 1953-011. Circular polarization and intensity spectra of the H spectral line demons…
Pulsation in the atmosphere of the roAp star HD 24712. I. Spectroscopic observations and radial velocity measurements
T. Ryabchikova, M. Sachkov, W. W. Weiss +10
We have investigated the structure of the pulsating atmosphere of one of the best studied rapidly oscillating Ap stars, HD 24712. For this purpose we analyzed spectra collected dur…
Polarimetry and photometry of the peculiar main-belt object 7968 = 133P/Elst-Pizarro
S. Bagnulo, G. P. Tozzi, H. Boehnhardt +2
133P/Elst-Pizarro is an object that has been described as either an active asteroid or a cometary object in the main asteroid belt. Here we present a photometric and polarimetric s…
The magnetic field of the pre-main sequence Herbig Ae star HD 190073
C. Catala, E. Alecian, J. -F. Donati +7
The general context of this paper is the study of magnetic fields in the pre-main sequence intermediate mass Herbig Ae/Be stars. Magnetic fields are likely to play an important rol…
Polarimetric Standardization
E. Landi Degl'Innocenti, S. Bagnulo, L. Fossati
The use of polarimetric techniques is nowadays widespread among solar and stellar astronomers. However, notwithstanding the recommandations that have often been made about the publ…
Characterisation of the magnetic fields of the Herbig Be stars HD 200775 and V380 0ri
E. Alecian, G. A. Wade, C. Catala +7
The origin of the magnetic fields of the chemically peculiar main sequence Ap/Bp stars is still matter of intense debate. The recent discoveries of magnetic fields in Herbig Ae/Be…
Atmospheric heating and magnetism driven by Ne distillation in isolated white dwarfs
A. F. Lanza, N. Z. Rui, J. Farihi +2
The origin of atmospheric heating in the cool, magnetic white dwarf GD 356 remains unsolved nearly 40 years after its discovery. This once idiosyncratic star with $T_{\rm eff}\appr…
Spectropolarimetry and photometry of the early afterglow of the gamma-ray burst GRB191221B
D. A. H. Buckley, S. Bagnulo, R. J. Britto +27
We report on results of spectropolarimetry of the afterglow of the long gamma-ray burst GRB 191221B, obtained with SALT/RSS and VLT/FORS2, as well as photometry from two telescopes…