144
144
Jul 20, 2013
07/13
by
D. Monin; D. Bohlender; T. Hardy; L. Saddlemyer; M. Fletcher
texts
eye 144
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A new, inexpensive polarimetric unit has been constructed for the Dominion Astrophysical Observatory (DAO) 1.8-m Plaskett telescope. It is implemented as a plug-in module for the telescope's existing Cassegrain spectrograph, and enables medium resolution (R~10,000) circular spectropolarimetry of point sources. A dual-beam design together with fast switching of the wave plate at rates up to 100Hz, and synchronized with charge shuffling on the CCD, is used to significantly reduce instrumental...
Source: http://arxiv.org/abs/1203.0278v1
47
47
Sep 19, 2013
09/13
by
C. Catala; J. -F. Donati; E. Shkolnik; D. Bohlender; E. Alecian
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eye 47
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We have obtained high resolution spectropolarimetric data for the planet-hosting star $\tau$ Bootis, using the ESPaDOnS spectropolarimeter at CFHT. A weak but clear Stokes $V$ signature is detected on three of the four nights of June 2006 during which we have recorded data. This polarimetric signature indicates with no ambiguity the presence of a magnetic field at the star's surface, with intensity of just a few Gauss. The analysis of the photospheric lines of $\tau$ Boo at ultra-high...
Source: http://arxiv.org/abs/astro-ph/0610758v1
64
64
Sep 21, 2013
09/13
by
V. Khalack; F. LeBlanc; B. B. Behr; G. A. Wade; D. Bohlender
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eye 64
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The observed slow rotation and abundance peculiarities of certain blue horizontal branch (BHB) stars suggests that atomic diffusion can be important in their stellar atmospheres and can lead to vertical abundance stratification of chemical species in the atmosphere. To verify this hypothesis, we have undertaken an abundance stratification analysis in the atmospheres of six BHB stars, based on recently acquired McDonald-CE spectra. Our numerical simulations show that the iron abundance is...
Source: http://arxiv.org/abs/0712.0809v1
51
51
Sep 22, 2013
09/13
by
V. R. Khalack; F. LeBlanc; D. Bohlender; G. A. Wade; B. B. Behr
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eye 51
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It is commonly believed that the observed overabundances of many chemical species relative to the expected cluster metallicity in blue horizontal branch (BHB) stars appear as a result of atomic diffusion in the photosphere. The slow rotation of BHB stars (with T_eff > 11,500K), typically v sin{i} < 10 km/s, is consistent with this idea. In this work we search for observational evidence of vertical chemical stratification in the atmosphere of HD135485. If this evidence exists, it will...
Source: http://arxiv.org/abs/astro-ph/0702134v1
55
55
Sep 23, 2013
09/13
by
V. R. Khalack; F. LeBlanc; B. B. Behr; G. A. Wade; D. Bohlender
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eye 55
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The observed abundance peculiarities of many chemical species relative to the expected cluster metallicity in blue horizontal-branch (BHB) stars presumably appear as a result of atomic diffusion in the photosphere. The slow rotation (typically $v\sin{i} $ 11,500 K supports this idea since the diffusion mechanism is only effective in a stable stellar atmosphere. In this work we search for observational evidence of vertical chemical stratification in the atmospheres of six hot BHB stars: B84,...
Source: http://arxiv.org/abs/0710.5330v2
55
55
Sep 23, 2013
09/13
by
L. Fossati; T. R. Ayres; C. A. Haswell; D. Bohlender; O. Kochukhov; L. Floeer
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eye 55
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Near-UV observations of the planet host star WASP-12 uncovered the apparent absence of the normally conspicuous core emission of the Mg2 h&k resonance lines. This anomaly could be due either to (1) a lack of stellar activity, which would be unprecedented for a solar-like star of the imputed age of WASP-12; or (2) extrinsic absorption, from the intervening interstellar medium (ISM) or from material within the WASP-12 system itself, presumably ablated from the extreme hot Jupiter WASP-12b....
Source: http://arxiv.org/abs/1303.3375v1
45
45
Sep 17, 2013
09/13
by
M. E. Oksala; G. A. Wade; W. L. F. Marcolino; J. Grunhut; D. Bohlender; N. Manset; R. H. D. Townsend; the MiMeS Collaboration
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eye 45
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We report the detection of a strong, organized magnetic field in the helium-variable early B-type star HR 7355 using spectropolarimetric data obtained with ESPaDOnS on the 3.6-m Canada-France-Hawaii Telescope within the context of the Magnetism in Massive Stars (MiMeS) Large Program. HR 7355 is both the most rapidly rotating known main-sequence magnetic star and the most rapidly rotating helium-strong star, with $v \sin i$ = 300 $\pm$ 15 km s$^{-1}$ and a rotational period of 0.5214404 $\pm$...
Source: http://arxiv.org/abs/1003.3626v1
3
3.0
Jun 30, 2018
06/18
by
I. Yakunin; G. Wade; D. Bohlender; O. Kochukhov; W. Marcolino; M. Shultz; D. Monin; J. Grunhut; T. Sitnova; V. Tsymbal; the MiMeS Collaboration
texts
eye 3
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A new time series of high-resolution Stokes I and V spectra of the magnetic B2V star HD 184927 has been obtained in the context of the Magnetism in Massive Stars (MiMeS) Large Program with the ESPaDOnS spectropolarimeter at the Canada-France-Hawaii Telescope and dimaPol liquid crystal spectropolarimeter at 1.8-m telescope of Dominion Astrophysical Observatory. We model the optical and UV spectrum obtained from the IUE archive to infer the stellar physical parameters. Using magnetic field...
Topics: Astrophysics, Solar and Stellar Astrophysics
Source: http://arxiv.org/abs/1411.5789
118
118
Jul 20, 2013
07/13
by
J. D. Bailey; J. Grunhut; M. Shultz; G. Wade; J. D. Landstreet; D. Bohlender; J. Lim; K. Wong; S. Drake; J. Linsky; the MiMeS Collaboration
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eye 118
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HD 133880 is a rapidly rotating Bp star and host to one of the strongest magnetic fields of any Bp star. A member of the Upper Centaurus Lupus association, it is a star with a well-determined age of 16 Myr. Twelve new spectra obtained from the FEROS, ESPaDOnS, and HARPS instruments, provide sufficient material from which to re-evaluate the magnetic field and obtain a first approximation to the atmospheric abundance distributions of various elements. Using the new magnetic field measurements and...
Source: http://arxiv.org/abs/1203.5277v2
3
3.0
Jun 30, 2018
06/18
by
E. Alecian; O. Kochukhov; V. Petit; J. Grunhut; J. Landstreet; M. E. Oksala; G. A. Wade; G. Hussain; C. Neiner; D. Bohlender; the MiMeS Collaboration
texts
eye 3
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To understand the origin of the magnetic fields in massive stars as well as their impact on stellar internal structure, evolution, and circumstellar environment, within the MiMeS project, we searched for magnetic objects among a large sample of massive stars, and build a sub-sample for in-depth follow-up studies required to test the models and theories of fossil field origins, magnetic wind confinement and magnetospheric properties, and magnetic star evolution. We obtained high-resolution...
Topics: Astrophysics, Solar and Stellar Astrophysics
Source: http://arxiv.org/abs/1404.5508
59
59
Sep 22, 2013
09/13
by
R. Fares; J. -F. Donati; C. Moutou; D. Bohlender; C. Catala; M. Deleuil; E. Shkolnik; A. C. Cameron; M. M. Jardine; G. A. H. Walker
texts
eye 59
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In this paper, we present new spectropolarimetric observations of the planet-hosting star Tau Bootis, using ESPaDOnS and Narval spectropolarimeters at Canada-France-Hawaii Telescope (CFHT) and Telescope Bernard Lyot (TBL), respectively. We detected the magnetic field of the star at three epochs in 2008. It is a weak magnetic field of only a few Gauss, oscillating between a predominant toroidal component in January and a dominant poloidal component in June and July. A magnetic polarity reversal...
Source: http://arxiv.org/abs/0906.4515v1
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55
Sep 17, 2013
09/13
by
R. Fares; J. -F. Donati; C. Moutou; M. M. Jardine; J. -M. Griessmeier; P. Zarka; E. L. Shkolnik; D. Bohlender; C. Catala; A. C. Cameron
texts
eye 55
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HD 189733 is a K2 dwarf, orbited by a giant planet at 8.8 stellar radii. In order to study magnetospheric interactions between the star and the planet, we explore the large-scale magnetic field and activity of the host star. We collected spectra using the ESPaDOnS and the NARVAL spectropolarimeters, installed at the 3.6-m Canada-France-Hawaii telescope and the 2-m Telescope Bernard Lyot at Pic du Midi, during two monitoring campaigns (June 2007 and July 2008). HD 189733 has a mainly toroidal...
Source: http://arxiv.org/abs/1003.6027v1
48
48
Sep 20, 2013
09/13
by
J. F. Donati; C. Moutou; R. Fares; D. Bohlender; C. Catala; M. Deleuil; E. Shkolnik; A. C. Cameron; M. M. Jardine; G. A. H. Walker
texts
eye 48
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We have obtained new spectropolarimetric observations of the planet-hosting star tauBootis, using the ESPaDOnS and NARVAL spectropolarimeters at the Canada-France-Hawaii Telescope and Telescope Bernard-Lyot. With this data set, we are able to confirm the presence of a magnetic field at the surface of tauBoo and map its large-scale structure over the whole star. The overall polarity of the magnetic field has reversed with respect to our previous observation (obtained a year before), strongly...
Source: http://arxiv.org/abs/0802.1584v1
50
50
Sep 20, 2013
09/13
by
E. Alecian; G. A. Wade; C. Catala; S. Bagnulo; T. Boehm; D. Bohlender; J. -C. Bouret; J. -F. Donati; C. P. Folsom; J. Grunhut; J. D. Landstreet
texts
eye 50
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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. Aims: To study the evolution of these magnetic fields, and their impact on the evolution of the angular momentum of these stars during the pre-main sequence phase, we observed Herbig Ae/Be members of young open clusters of various ages. Methods: We obtained high-resolution spectropolarimetric observations of Herbig...
Source: http://arxiv.org/abs/0802.4078v1
83
83
Jul 20, 2013
07/13
by
L. Fossati; S. Bagnulo; A. Elmasli; C. A. Haswell; S. Holmes; O. Kochukhov; E. L. Shkolnik; D. V. Shulyak; D. Bohlender; B. Albayrak; C. Froning; L. Hebb
texts
eye 83
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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 only visible component and therefore used to infer the planet's fundamental parameters. Another important aspect of the analysis of planetary systems is the stellar activity and the possible star-planet interaction. Here we present a self-consistent abundance analysis of the planet hosting star WASP-12 and a...
Source: http://arxiv.org/abs/1007.3082v1
35
35
Sep 18, 2013
09/13
by
M. Breger; L. Fossati; L. Balona; D. W. Kurtz; P. Robertson; D. Bohlender; P. Lenz; I. Mueller; Th. Lueftinger; Bruce D. Clarke; Jennifer R. Hall; Khadeejah A. Ibrahim
texts
eye 35
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Two years of Kepler data of KIC 8054146 (delta Sct/gamma Dor hybrid) revealed 349 statistically significant frequencies between 0.54 and 191.36 c/d (6.3 microHz to 2.21 mHz). The 117 low frequencies cluster in specific frequency bands, but do not show the equidistant period spacings predicted for gravity modes of successive radial order, n, and reported for at least one other hybrid pulsator. The four dominant low frequencies in the 2.8 to 3.0 c/d (32 to 35 microHz) range show strong amplitude...
Source: http://arxiv.org/abs/1209.4836v1
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44
Sep 24, 2013
09/13
by
R. Fares; J. -F. Donati; C. Moutou; M. Jardine; A. C. Cameron; A. Lanza; D. Bohlender; S. Dieters; A. Martinez Fiorenzano; A. Maggio; I Pagano; E. L. Shkolnik
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eye 44
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HD 179949 is an F8V star, orbited by a giant planet at ~8 R* every 3.092514 days. The system was reported to undergo episodes of stellar activity enhancement modulated by the orbital period, interpreted as caused by Star-Planet Interactions (SPIs). One possible cause of SPIs is the large-scale magnetic field of the host star in which the close-in giant planet orbits. In this paper we present spectropolarimetric observations of HD 179949 during two observing campaigns (2009 September and 2007...
Source: http://arxiv.org/abs/1202.4472v2
5
5.0
Jun 30, 2018
06/18
by
E. Alecian; C. Neiner; G. A. Wade; S. Mathis; D. Bohlender; D. Cébron; C. Folsom; J. Grunhut; J. -B. Le Bouquin; V. Petit; H. Sana; A. Tkachenko; A. ud-Doula; the BinaMIcS collaboration
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eye 5
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It is now well established that a fraction of the massive (M>8 Msun) star population hosts strong, organised magnetic fields, most likely of fossil origin. The details of the generation and evolution of these fields are still poorly understood. The BinaMIcS project takes an important step towards the understanding of the interplay between binarity and magnetism during the stellar formation and evolution, and in particular the genesis of fossil fields, by studying the magnetic properties of...
Topics: Astrophysics, Solar and Stellar Astrophysics
Source: http://arxiv.org/abs/1409.1094
60
60
Sep 21, 2013
09/13
by
G. Scandariato; A. Maggio; A. F. Lanza; I. Pagano; R. Fares; E. L. Shkolnik; D. Bohlender; A. C. Cameron; S. Dieters; J. -F. Donati; A. F. Martìnez Fiorenzano; M. Jardine; C. Moutou
texts
eye 60
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HD179949 is an F8V star, orbited by a close-in giant planet with a period of ~3 days. Previous studies suggested that the planet enhances the magnetic activity of the parent star, producing a chromospheric hot spot which rotates in phase with the planet orbit. However, this phenomenon is intermittent since it was observed in several but not all seasons. A long-term monitoring of the magnetic activity of HD179949 is required to study the amplitude and time scales of star-planet interactions. In...
Source: http://arxiv.org/abs/1301.7748v1
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55
Jul 20, 2013
07/13
by
R. H. D. Townsend; Th. Rivinius; J. F. Rowe; A. F. J. Moffat; J. M. Matthews; D. Bohlender; C. Neiner; J. H. Telting; D. B. Guenther; T. Kallinger; R. Kuschnig; S. M. Rucinski; D. Sasselov; W. W. Weiss
texts
eye 55
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We present results from three weeks' photometric monitoring of the magnetic helium-strong star sigma Ori E using the MOST microsatellite. The star's light curve is dominated by twice-per-rotation eclipse-like dimmings arising when magnetospheric clouds transit across and occult the stellar disk. However, no evidence is found for any abrupt centrifugal breakout of plasma from the magnetosphere, either in the residual flux or in the depths of the light minima. Motivated by this finding we compare...
Source: http://arxiv.org/abs/1304.2392v1
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53
Sep 19, 2013
09/13
by
J. H. Grunhut; G. A. Wade; W. L. F. Marcolino; V. Petit; H. F. Henrichs; D. H. Cohen; E. Alecian; D. Bohlender; J. -C. Bouret; O. Kochukhov; C. Neiner; N. St-Louis; R. H. D. Townsend; the MiMeS Collaboration
texts
eye 53
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We report the detection of a strong, organised magnetic field in the O9IV star HD 57682, using spectropolarimetric observations obtained with ESPaDOnS at the 3.6-m Canada-France-Hawaii Telescope within the context of the Magnetism in Massive Stars (MiMeS) Large Program. From the fitting of our spectra using NLTE model atmospheres we determined that HD 57682 is a $17^{+19}_{-9}$ M$_{\odot}$ star with a radius of $7.0^{+2.4}_{-1.8}$ R$_\odot$, and a relatively low mass-loss rate of...
Source: http://arxiv.org/abs/0910.0214v1
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61
Sep 22, 2013
09/13
by
K. Zwintz; L. Fossati; D. B. Guenther; T. Ryabchikova; A. Baglin; N. Themessl; T. G. Barnes; J. M. Matthews; M. Auvergne; D. Bohlender; S. Chaintreuil; R. Kuschnig; A. F. J. Moffat; J. F. Rowe; S. M. Rucinski; D. Sasselov; W. W. Weiss
texts
eye 61
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We concentrate on an asteroseismological study of HD 261711, a rather hot delta Scuti type pulsating member of the young open cluster NGC 2264 located at the blue border of the instability region. HD 261711 was discovered to be a pre-main sequence delta Scuti star using the time series photometry obtained by the MOST satellite in 2006. High-precision, time-series photometry of HD 261711 was obtained by the MOST and CoRoT satellites in 4 separate new observing runs that are put into context with...
Source: http://arxiv.org/abs/1302.3369v1
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71
Sep 18, 2013
09/13
by
Ian D. Howarth; Nolan R. Walborn; Danny J. Lennon; Joachim Puls; Yael Naze; K. Annuk; I. Antokhin; D. Bohlender; H. Bond; J. -F. Donati; L. Georgiev; D. Gies; D. Harmer; A. Herrero; I. Kolka; D. McDavid; T. Morel; I. Negueruela; G. Rauw; P. Reig
texts
eye 71
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We present extensive optical spectroscopy of the early-type magnetic star HD 191612 (O6.5f?pe-O8fp). The Balmer and HeI lines show strongly variable emission which is highly reproducible on a well-determined 538-d period. Metal lines and HeII absorptions (including many selective emission lines but excluding He II 4686A emission) are essentially constant in line strength, but are variable in velocity, establishing a double-lined binary orbit with P(orb) = 1542d, e=0.45. We conduct a...
Source: http://arxiv.org/abs/0707.0594v1
