2,406 research outputs found
Harm Reduction en la Ciudad de Nueva York
Entrevistamos especialistas del Educadores de la Reducción de Daños de Nueva York y Sarah Evans quien era un líder del primero centro de la prevención de sobredosis en America Norte. Encontramos que este campo es una solución pragmática para la crisis de addición a los opioides.
Spanish - https://dimitrifautsch.medium.com/la-reducci%C3%B3n-de-da%C3%B1os-en-nueva-york-a0a8c8ccef4a
English - https://jasongonzalez76.wixsite.com/website/post/new-york-s-first-supervised-safe-injection-sites-are-a-first-of-its-kind-in-the-united-state
Peanut-shaped metallicity distributions in bulges of edge-on galaxies: the case of NGC 4710
Bulges of edge-on galaxies are often boxy/peanut-shaped (B/PS), and unsharp masks reveal the presence of an X shape. Simulations show that these shapes can be produced by dynamical processes driven by a bar which vertically thickens the centre. In the Milky Way, which contains such a B/PS bulge, the X-shaped structure is traced by the metal-rich stars but not
by the metal-poor ones. Recently, Debattista et al. interpreted this property as a result of the varying effect of the bar on stellar populations with different starting kinematics. This kinematic fractionation model predicts that cooler populations at the time of bar formation go on to trace the X shape, whereas hotter populations are more uniformly distributed. As this
prediction is not specific to the Milky Way, we test it with Multi Unit Spectroscopic Explorer (MUSE) observations of the B/PS bulge in the nearby galaxy NGC 4710. We show that the metallicity map is more peanut-shaped than the density distribution itself, in good agreement with the prediction. This result indicates that the X-shaped structure in B/PS bulges is formed of relatively metal-rich stars that have been vertically redistributed by the bar, whereas the metal-poor stars have more uniform, box-shaped distribution
Peanut-shaped metallicity distributions in bulges of edge-on galaxies: the case of NGC 4710
Bulges of edge-on galaxies are often boxy/peanut-shaped (B/PS), and unsharp masks reveal the presence of an X shape. Simulations show that these shapes can be produced by dynamical processes driven by a bar which vertically thickens the centre. In the Milky Way, which contains such a B/PS bulge, the X-shaped structure is traced by the metal-rich stars but not
by the metal-poor ones. Recently, Debattista et al. interpreted this property as a result of the varying effect of the bar on stellar populations with different starting kinematics. This kinematic fractionation model predicts that cooler populations at the time of bar formation go on to trace the X shape, whereas hotter populations are more uniformly distributed. As this
prediction is not specific to the Milky Way, we test it with Multi Unit Spectroscopic Explorer (MUSE) observations of the B/PS bulge in the nearby galaxy NGC 4710. We show that the metallicity map is more peanut-shaped than the density distribution itself, in good agreement with the prediction. This result indicates that the X-shaped structure in B/PS bulges is formed of relatively metal-rich stars that have been vertically redistributed by the bar, whereas the metal-poor stars have more uniform, box-shaped distribution
Discovery of a White Dwarf Companion to HD 159062
We report on the discovery of a white dwarf companion to the nearby late G
dwarf star, HD 159062. The companion is detected in 14 years of precise radial
velocity (RV) data, and in high-resolution imaging observations. RVs of HD
159062 from 2003-2018 reveal an acceleration of ,
indicating that it hosts a companion with a long-period orbit. Subsequent
imaging observations with the ShaneAO system on the Lick Observatory 3-meter
Shane telescope, the PHARO AO system on the Palomar Observatory 5-meter
telescope, and the NIRC2 AO system at the Keck II 10-meter telescope reveal a
faint companion 2.7'' from the primary star. We performed relative photometry,
finding magnitudes,
magnitudes, and magnitudes for the companion from
these observations. Analysis of the radial velocities, astrometry, and
photometry reveals that the combined data set can only be reconciled for the
scenario where HD 159062 B is a white dwarf. A full Bayesian analysis of the RV
and imaging data to obtain the cooling age, mass, and orbital parameters of the
white dwarf indicates that the companion is an old white dwarf with an orbital period of years, and a cooling age of Gyr.Comment: 10 pages, 9 figure
Discovery of a Companion Candidate in the HD169142 Transition Disk and the Possibility of Multiple Planet Formation
We present L' and J-band high-contrast observations of HD169142, obtained
with the VLT/NACO AGPM vector vortex coronagraph and the Gemini Planet Imager,
respectively. A source located at 0".156+/-0".032 north of the host star
(PA=7.4+/-11.3 degrees) appears in the final reduced L' image. At the distance
of the star (~145 pc), this angular separation corresponds to a physical
separation of 22.7+/-4.7 AU, locating the source within the recently resolved
inner cavity of the transition disk. The source has a brightness of
L'=12.2+/-0.5 mag, whereas it is not detected in the J band (J>13.8 mag). If
its L' brightness arose solely from the photosphere of a companion and given
the J-L' color constraints, it would correspond to a 28-32 MJupiter object at
the age of the star, according to the COND models. Ongoing accretion activity
of the star suggests, however, that gas is left in the inner disk cavity from
which the companion could also be accreting. In this case the object could be
lower in mass and its luminosity enhanced by the accretion process and by a
circumplanetary disk. A lower mass object is more consistent with the observed
cavity width. Finally, the observations enable us to place an upper limit on
the L'-band flux of a second companion candidate orbiting in the disk annular
gap at ~50 AU, as suggested by millimeter observations. If the second companion
is also confirmed, HD169142 might be forming a planetary system, with at least
two companions opening gaps and possibly interacting with each other.Comment: Accepted to ApJL, see also Biller et al. 201
A Planet at 5 AU Around 55 Cancri
We report precise Doppler shift measurements of 55 Cancri (G8V) obtained from
1989 to 2002 at Lick Observatory. The velocities reveal evidence for an outer
planetary companion to 55 Cancri orbiting at 5.5 AU. The velocities also
confirm a second, inner planet at 0.11 AU. The outer planet is the first
extrasolar planet found that orbits near or beyond the orbit of Jupiter. It was
drawn from a sample of ~50 stars observed with sufficient duration and quality
to detect a giant planet at 5 AU, implying that such planets are not rare. The
properties of this jupiter analog may be compared directly to those of the
Jovian planets in our Solar System. Its eccentricity is modest, e=0.16,
compared with e=0.05 for both Jupiter and Saturn. Its mass is at least 4.0
jupiter masses (M sin i). The two planets do not perturb each other
significantly. Moreover, a third planet of sub-Jupiter mass could easily
survive in between these two known planets. Indeed a third periodicity remains
in the velocity measurements with P = 44.3 d and a semi-amplitude of 13 m/s.
This periodicity is caused either by a third planet at a=0.24 AU or by
inhomogeneities on the stellar surface that rotates with period 42 d. The
planet interpretation is more likely, as the stellar surface is quiet,
exhibiting log(R'_{HK}) = -5.0 and brightness variations less than 1 millimag,
and any hypothetical surface inhomogeneity would have to persist in longitude
for 14 yr. Even with all three planets, an additional planet of
terrestrial--mass could orbit stably at ~1 AU. The star 55 Cancri is apparently
a normal, middle-aged main sequence star with a mass of 0.95 solar masses, rich
in heavy elements ([Fe/H] = +0.27). This high metallicity raises the issue of
the relationship between its age, rotation, and chromosphere.Comment: 47 pages, 4 tables, 12 figures, uses AASTE
The VORTEX project: first results and perspectives
(abridged) Vortex coronagraphs are among the most promising solutions to
perform high contrast imaging at small angular separations. They feature a very
small inner working angle, a clear 360 degree discovery space, have
demonstrated very high contrast capabilities, are easy to implement on
high-contrast imaging instruments, and have already been extensively tested on
the sky. Since 2005, we have been designing, developing and testing an
implementation of the charge-2 vector vortex phase mask based on concentric
subwavelength gratings, referred to as the Annular Groove Phase Mask (AGPM).
Science-grade mid-infrared AGPMs were produced in 2012 for the first time,
using plasma etching on synthetic diamond substrates. They have been validated
on a coronagraphic test bench, showing broadband peak rejection up to 500:1 in
the L band, which translates into a raw contrast of about at
. Three of them have now been installed on world-leading
diffraction-limited infrared cameras (VLT/NACO, VLT/VISIR and LBT/LMIRCam).
During the science verification observations with our L-band AGPM on NACO, we
observed the beta Pictoris system and obtained unprecedented sensitivity limits
to planetary companions down to the diffraction limit (). More recently,
we obtained new images of the HR 8799 system at L band during the AGPM first
light on LMIRCam. After reviewing these first results obtained with
mid-infrared AGPMs, we will discuss the short- and mid-term goals of the
on-going VORTEX project, which aims to improve the performance of our vortex
phase masks for future applications on second-generation high-contrast imagers
and on future extremely large telescopes (ELTs).Comment: To appear in SPIE proceedings vol. 914
Three years of harvest with the vector vortex coronagraph in the thermal infrared
For several years, we have been developing vortex phase masks based on
sub-wavelength gratings, known as Annular Groove Phase Masks. Etched onto
diamond substrates, these AGPMs are currently designed to be used in the
thermal infrared (ranging from 3 to 13 {\mu}m). Our AGPMs were first installed
on VLT/NACO and VLT/VISIR in 2012, followed by LBT/LMIRCam in 2013 and
Keck/NIRC2 in 2015. In this paper, we review the development, commissioning,
on-sky performance, and early scientific results of these new coronagraphic
modes and report on the lessons learned. We conclude with perspectives for
future developments and applications.Comment: To appear in SPIE proceedings vol. 990
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