11,992 research outputs found
High-resolution [C II] imaging of HDF850.1 reveals a merging galaxy at z=5.185
New high-resolution maps with the IRAM Interferometer of the redshifted [C
II] 158 micron line and the 0.98mm dust continuum of HDF850.1 at z = 5.185 show
the source to have a blueshifted northern component and a redshifted southern
component, with a projected separation of 0.3 arcsec, or 2 kpc. We interpret
these components as primordial galaxies that are merging to form a larger
galaxy. We think it is the resulting merger-driven starburst that makes
HDF850.1 an ultraluminous infrared galaxy, with an L(IR) of 1E13 Lsun. The
observed line and continuum brightness temperatures and the constant
line-to-continuum ratio across the source imply (1) high [C II] line optical
depth, (2) a [C II] excitation temperature of the same order as the dust
temperature, and (3) dust continuum emission that is nearly optically thick at
158 microns. These conclusions for HDF850.1 probably also apply to other
high-redshift submillimeter galaxies and quasar hosts in which the [C II] 158
micron line has been detected, as indicated by their roughly constant [C
II]-to-158 micron continuum ratios, in sharp contrast to the large dispersion
in their [C II]-to-FIR luminosity ratios. In brightness temperature units, the
[C II] line luminosity is about the same as the predicted CO(1-0) luminosity,
implying that the [C II] line can also be used to estimate the molecular gas
mass, with the same assumptions as for CO.Comment: Accepted by Astronomy and Astrophysic
SHIP MOTION SHORT TERM TIME DOMAIN SIMULATOR AND ITS APPLICATION TO COSTA CONCORDIA EMERGENCY MANOEUVRES JUST BEFORE THE JANUARY 2012 ACCIDENT
In this paper we will present a simple but reliable methodology for short term prediction of a cruise ship behaviour during manoeuvres. The methodology is quite general and could be applied to any kind of ship, because it does not require the prior knowledge of any structural or mechanical parameter of the ship. It is based only on the results of manoeuvrability data contained in the Manoeuvring Booklet, which in turn is filled out after sea trials of the ship performed before his delivery to the owner.
We developed this method to support the investigations around the Costa Concordia shipwreck, which happened near the shores of Italy in January 2012. It was then validated against the data recorded in the “black box” of the ship, from which we have been able to extract an entire week of voyage data before the shipwreck. The aim was investigating the possibility of avoiding the impact by performing an evasive manoeuvre (as ordered by the Captain some seconds before the impact, but allegedly misunderstood by the helmsman). The preliminary validation step showed a good matching between simulated and real values (course and heading of the ship) for a time interval of a few minutes.
The fact that the method requires only the results registered in the VDR (Voyage Data Recorder) during sea trial tests, makes it very useful for several applications. Among them, we can cite forensic investigation, the development of components for autopilots, the prediction of the effects of a given manoeuvre in shallow water, the “a posteriori” verification of the correctness of a given manoeuvre and the use in training simulators for ship pilots and masters
Action perception is intact in autism spectrum disorder
Date of Acceptance:10/11/2014. Copyright © 2015 the authors 0270-6474/15/351849-09$15.00/0. Copyright of all material published in The Journal of Neuroscience remains with the authors. The authors grant the Society for Neuroscience an exclusive license to publish their work for the first 6 months. After 6 months the work becomes available to the public to copy, distribute, or display under a Creative Commons Attribution 4.0 International (CC BY 4.0) license.Peer reviewedPublisher PD
A Keplerian gaseous disk around the B0 star R Mon
We present high-angular resolution observations of the circumstellar disk
around the massive Herbig Be star R Mon (M~8 Msun) in the continuum at 2.7mm
and 1.3mm and the CO 1->0 and 2->1 rotational lines. Based on the new 1.3mm
continuum image we estimate a disk mass (gas+dust) of 0.007 Msun and an outer
radius of <150 AU. Our CO images are consistent with the existence of a
Keplerian rotating gaseous disk around this star. Up to our knowledge, this is
the most clear evidence for the existence of Keplerian disks around massive
stars reported thus far. The mass and physical characteristics of this disk are
similar to thoseof the more evolved T Tauri stars and indicate a shorter
timescale for the evolution and dispersal of circumstellar disks around massive
stars which lose most of their mass before the star becomes visible.Comment: 5 page
A Kiloparsec-Scale Hyper-Starburst in a Quasar Host Less than 1 Gigayear after the Big Bang
The host galaxy of the quasar SDSS J114816.64+525150.3 (at redshift z=6.42,
when the Universe was <1 billion years old) has an infrared luminosity of
2.2x10^13 L_sun, presumably significantly powered by a massive burst of star
formation. In local examples of extremely luminous galaxies such as Arp220, the
burst of star formation is concentrated in the relatively small central region
of <100pc radius. It is unknown on which scales stars are forming in active
galaxies in the early Universe, which are likely undergoing their initial burst
of star formation. We do know that at some early point structures comparable to
the spheroidal bulge of the Milky Way must have formed. Here we report a
spatially resolved image of [CII] emission of the host galaxy of
J114816.64+525150.3 that demonstrates that its star forming gas is distributed
over a radius of ~750pc around the centre. The surface density of the star
formation rate averaged over this region is ~1000 M_sun/yr/kpc^2. This surface
density is comparable to the peak in Arp220, though ~2 orders of magnitudes
larger in area. This vigorous star forming event will likely give rise to a
massive spheroidal component in this system.Comment: Nature, in press, Feb 5 issue, p. 699-70
Detection of a hot core in the intermediate-mass (IM) Class 0 protostar NGC 7129--FIRS2
We report high angular resolution (~0.6''x0.5'' at 1.3mm) observations of the
Class 0 intermediate-mass (IM) protostar NGC 7129--FIRS 2 using the PdBI. Our
observations show the existence of a hot core at the position of the Class 0
object. This is, up to our knowledge, the first IM hot core detected so far.
Interferometric maps of the region in the the continuum at 3mm and 1.3mm and in
the CH3CN 5_k-->4_k, CH3OH 5_kk'-->4_kk', and D2CO 4_04-->3_03 lines are
presented in this paper. Enhanced CH3CN and CH3OH abundances are measured
towards the hot core (X(CH3CN)~7.010^{-9}, X(CH3OH)~3 10^{-8}-- a few 10^{-7}).
While intense D2CO emission is detected towards the hot core, the N2D+ line has
not been detected in our interferometric observations. The different behaviors
of D2CO and N2D+ emissions suggest different formation mechanisms for the two
species and different deuteration processes for H2CO and N2H+ (surface and
gas-phase chemistry, respectively). Finally, the spectrum of the large
bandwidth correlator show a forest of lines at the hot core position revealing
that this object is extraordinarily rich in complex molecules.Comment: 14 pages, 7 figures, accepted for publication in Astronomy &
Astrophysic
Multiple Molecular H2 Outflows in AFGL 618
We report high spatial (0.5 arcsec) and high spectral (9 km/s) resolution
spectro-imaging of the 2.12 micron H2 1-0 S(1) line in the proto-planetary
nebula AFGL 618 using BEAR at the CFHT. The observations reveal the presence of
multiple, high-velocity, molecular outflows that align with the remarkable
optical jets seen in HST images. The structure and kinematics of the outflows
show how jets interact with circumstellar gas and shape the environment in
which planetary nebulae form.Comment: 14 pages, 5 figures. To appear in The Astrophysical Journal Letter
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