87,343 research outputs found
Heidegger and Phenomenology. Westerlund, F. (2020). Heidegger and the Problem of Phenomena. London: Bloomsbury.
No full textОгляд книги Westerlund, F. (2020). Heidegger and the Problem of Phenomena. London:BloomsburyReview of Westerlund, F. (2020). Heidegger and the Problem of Phenomena. London:Bloomsbur
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Westerlund 1 and 2 Open Clusters Survey
No full textContext. With a mass exceeding several 104 M and a rich and dense population of massive stars, supermassive young star clusters represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions among stars.Aims. In this paper we present the "Extended Westerlund 1 and 2 Open Clusters Survey" (EWOCS) project, which aims to investigate the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars. The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically, the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec. Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation were carried out using the ACIS-Extract software.Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a photon flux threshold of approximately 2 × 10−8 photons cm−2 s−1. The X-ray sources exhibit a highly concentrated spatial distribution, with 1075 sources located within the central 1 arcminute. We have successfully detected X-ray emissions from 126 out of the 166 known massive stars of the cluster, and we have collected over 71000 photons from the magnetar CXO J164710.20-455217
The endemic Oxychilus species of Lampedusa (Pelagian Islands, Italy): O. diductus (Westerlund, 1886) (Pulmonata, Zonitidae)
No full textOxychilus diductus (Westerlund, 1886) is redescribed. The species is the only one of the genus Oxychilus living in the Pelagian Islands, an archipelago off the northern coast of Tunisia, and is endemic to Lampedusa. O. diductus can be identified by draparnaudi-like anatomy and shell depressed, discoidal, not "polygyrate", with umbilicus wide and external surface irregularly striated, opaque and with finely granulated microsculpture
Houston Yacht Club Commodore Henry Westerlund, 1973-1974
No full textWesterlund served as Commodore 1973-1974
Detection of additional Wolf-Rayet stars in the starburst cluster Westerlund 1 with
No full textContext.The young starburst cluster Westerlund 1 is one of the most massive clusters in the Local Group,
harboring a huge population of massive stars.
Aims.We searched for additional Wolf-Rayet stars in Westerlund 1.
Methods.The targets were selected based on 1 μm narrow-band imaging of
the cluster carried out at OPD/LNA (Brazil), and then confirmed as Wolf-Rayet stars by K-band
spectroscopy performed at the 4.1 m SOAR telescope (Chile).
Results.We report the detection of 3 additional Wolf-Rayet stars in Westerlund 1. Together with previous
works, this increases the population of Wolf-Rayet stars detected in the cluster to 22 members.
Moreover, a K-band spectrum of the Luminous Blue Variable W243,
which apparently implies a higher temperature than that derived from optical spectra taken in
2003, is presented for the first time. The WC9 star WR-F was also observed, showing clear evidence of dust emission in the K-band
Unveiling very young O stars. Two Galactic O2V((f*))z in Westerlund 2
No full textO-type stars are known to significantly contribute to both the dynamics and
evolution of galaxies. Massive and luminous, they probably control and regulate
the galaxies star formation rates. For this work I performed a redetermination
of the spectral types and effective temperatures of the Galactic O-type stars
MSP182, MSP183, MSP199, VPHAS-01338, and VPHAS-01273. From a careful
examination of the spectral features present in the blue optical spectral
region, it was possible to identify several nitrogen lines usually only seen in
the blue optical spectra of O2-O3 stars. From the nitrogen ionic equivalent
width ratios measured in the spectra of MSP182, MSP183, MSP199, VPHAS-01338,
and VPHAS-01273, and in those of standard stars of the O2-O4 spectral types,
earlier spectral types and hotter effective temperature values were derived.
Two O2V, together with three new O3V stars, are now firmly identified in the
Westerlund 2 region. Besides RFS1 in NGC3603, the O2 stars found in Westerlund
2 are the only other exemplars known to date in the Milky Way. From the
nitrogen equivalent width line ratios measured in the spectra of standard stars
of the O2-O4 spectral types, linear relations between the NIV4058-NIII4640
ratio and the effective temperature in the 47000K-51000K range were derived.
Based on my spectroscopic analysis of the science targets and the use of a HRD,
a mean heliocentric distance of 5kpc to Westerlund 2 was computed, a result
that is in line with the mean heliocentric distance of 5.3(1.5) kpc obtained
from the associated Gaia DR3 parallaxes and distances. The Westerlund 2 massive
stars studied in this work probably share a common evolutionary process that
might be representative of the evolutionary ages of a large fraction of the
cluster's O-type stellar population, which seems to be much younger than 1
Myrs.Comment: 8 pages, 5 figures, accepted for publication in Astronomy and
Astrophysics (DOI(pending):10.1051/0004-6361/202449474
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Westerlund 1 and 2 Open Clusters Survey
No full textContext. With a mass exceeding several 104 M_sun and a rich and dense population of massive stars, supermassive young star clusters represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions among stars.
Aims: In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars. The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods: The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically, the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec. Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation were carried out using the ACIS-Extract software.
Results: The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a photon flux threshold of approximately 2 × 10−8 photons cm−2 s−1. The X-ray sources exhibit a highly concentrated spatial distribution, with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217
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The Wolf-Rayet population of Westerlund 1
No full textNew NTT/SOFI near-IR narrow-band imaging and spectroscopy reveals an additional four Wolf-Rayet (WR) stars in the massive cluster Westerlund 1, bringing the total WR population to 24. Sixteen of the WR stars in Wd1 have been classified WN5–11, while eight are WC8–9. An observed WR to RSG/YHG ratio of ∼3 suggests an age of 4.5–5.0 Myr, with WR stars descended from 40–55MSolar progenitors. On the basis of dust and hard X-ray emission, we estimate that 40–65% are probable members of massive star binary systems
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Westerlund 1 and 2 Open Clusters Survey
No full textInternational audienceContext. With a mass exceeding several 10^4 solar masses and a rich and dense population of massive stars, supermassive young star clusters represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions among stars. Aims. In this paper we present the "Extended Westerlund 1 and 2 Open Clusters Survey" (EWOCS) project, which aims to investigate the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars. The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun. Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically, the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec. Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation were carried out using the ACIS-Extract software. Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a photon flux threshold of approximately 2x10^-8 photons/cm^2/s. The X-ray sources exhibit a highly concentrated spatial distribution, with 1075 sources located within the central 1 arcminute. We have successfully detected X-ray emissions from 126 out of the 166 known massive stars of the cluster, and we have collected over 71000 photons from the magnetar CXO J164710.20-45521
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