17,868 research outputs found
Probing the distance and morphology of the Large Magellanic Cloud with RR Lyrae stars
We present a Bayesian analysis of the distances to 15,040 Large Magellanic
Cloud (LMC) RR Lyrae stars using - and -band light curves from the
Optical Gravitational Lensing Experiment, in combination with new -band
observations from the Dark Energy Camera. Our median individual RR Lyrae
distance statistical error is 1.89 kpc (fractional distance error of 3.76 per
cent). We present three-dimensional contour plots of the number density of LMC
RR Lyrae stars and measure a distance to the core LMC RR Lyrae centre of
,
equivalently . This finding is statistically consistent with and four
times more precise than the canonical value determined by a recent
meta-analysis of 233 separate LMC distance determinations. We also measure a
maximum tilt angle of at a position angle of
, and report highly precise constraints on the , , and RR
Lyrae period--magnitude relations. The full dataset of observed mean-flux
magnitudes, derived colour excess values, and fitted distances for
the 15,040 RR Lyrae stars produced through this work is made available through
the publication's associated online data.Comment: 7 pages, 8 figure
The Discovery of Vibrationally-Excited H_2 in the Molecular Cloud near GRB 080607
GRB 080607 has provided the first strong observational signatures of
molecular absorption bands toward any galaxy hosting a gamma-ray burst. Despite
the identification of dozens of features as belonging to various atomic and
molecular (H_2 and CO) carriers, many more absorption features remained
unidentified. Here we report on a search among these features for absorption
from vibrationally-excited H_2, a species that was predicted to be produced by
the UV flash of a GRB impinging on a molecular cloud. Following a detailed
comparison between our spectroscopy and static, as well as dynamic, models of
H_2* absorption, we conclude that a column density of 10^{17.5+-0.2} cm^{-2} of
H_2* was produced along the line of sight toward GRB 080607. Depending on the
assumed amount of dust extinction between the molecular cloud and the GRB, the
model distance between the two is found to be in the range 230--940 pc. Such a
range is consistent with a conservative lower limit of 100 pc estimated from
the presence of Mg I in the same data. These distances show that substantial
molecular material is found within hundreds of pc from GRB 080607, part of the
distribution of clouds within the GRB host galaxy.Comment: Submitted to ApJL, 6 pages emulate
Multi-color Optical and NIR Light Curves of 64 Stripped-Envelope Core-Collapse Supernovae
We present a densely-sampled, homogeneous set of light curves of 64 low
redshift (z < 0.05) stripped-envelope supernovae (SN of type IIb, Ib, Ic and
Ic-bl). These data were obtained between 2001 and 2009 at the Fred L. Whipple
Observatory (FLWO) on Mt. Hopkins in Arizona, with the optical FLWO 1.2-m and
the near-infrared PAIRITEL 1.3-m telescopes. Our dataset consists of 4543
optical photometric measurements on 61 SN, including a combination of UBVRI,
UBVr'i', and u'BVr'i', and 2142 JHKs near-infrared measurements on 25 SN. This
sample constitutes the most extensive multi-color data set of stripped-envelope
SN to date. Our photometry is based on template-subtracted images to eliminate
any potential host galaxy light contamination. This work presents these
photometric data, compares them with data in the literature, and estimates
basic statistical quantities: date of maximum, color, and photometric
properties. We identify promising color trends that may permit the
identification of stripped-envelope SN subtypes from their photometry alone.
Many of these SN were observed spectroscopically by the CfA SN group, and the
spectra are presented in a companion paper (Modjaz et al. 2014). A thorough
exploration that combines the CfA photometry and spectroscopy of
stripped-envelope core-collapse SN will be presented in a follow-up paper.Comment: 26 pages, 17 figures, 8 tables. Revised version resubmitted to ApJ
Supplements after referee report. Additional online material is available
through http://cosmo.nyu.edu/SNYU
Discovery of a supernova associated with GRB 031203: SMARTS Optical-Infrared Lightcurves from 0.2 to 92 days
Optical and infrared monitoring of the afterglow site of gamma-ray burst
(GRB) 031203 has revealed a brightening source embedded in the host galaxy,
which we attribute to the presence of a supernova (SN) related to the GRB ("SN
031203"). We present details of the discovery and evolution of SN 031203 from
0.2 to 92 days after the GRB, derived from SMARTS consortium photometry in I
and J bands. A template type Ic lightcurve, constructed from SN 1998bw
photometry, is consistent with the peak brightness of SN 031203 although the
lightcurves are not identical. Differential astrometry reveals that the SN, and
hence the GRB, occurred less than 300 h_71^-1 pc (3-sigma) from the apparent
galaxy center. The peak of the supernova is brighter than the optical afterglow
suggesting that this source is intermediate between a strong GRB and a
supernova.Comment: 11 pages, 3 figures, submitted to ApJ Letter
The impact of health on professionally active people's incomes in Poland. Microeconometric analysis
The outcome of the research confirms the occurrence of positive interaction between professionally active people's incomes and the self-assessed state of health. People declaring a bad state of health have incomes by 20% on average lower than people who enjoy good health (assuming that the remaining characteristics of the surveyed person are the same). In case of men, the impact of health state on incomes is slightly greater than in case of women.Wyniki badań potwierdzają istnienie pozytywnej zależności dochodów osób aktywnych zawodowo od stanu zdrowia mierzonego jego samooceną. Osoby deklarujące zły stan zdrowia osiągają dochody przeciętnie o 20% niższe niż osoby, które cieszą się dobrym stanem zdrowia (przy założeniu, że pozostałe charakterystyki badanej osoby są takie same). W przypadku mężczyzn zależność dochodów od stanu zdrowia jest nieznacznie silniejsza niż w przypadku kobiet
Systematic study of Optical Feshbach Resonances in an ideal gas
Using a narrow intercombination line in alkaline earth atoms to mitigate
large inelastic losses, we explore the Optical Feshbach Resonance (OFR) effect
in an ultracold gas of bosonic Sr. A systematic measurement of three
resonances allows precise determinations of the OFR strength and scaling law,
in agreement with coupled-channels theory. Resonant enhancement of the complex
scattering length leads to thermalization mediated by elastic and inelastic
collisions in an otherwise ideal gas. OFR could be used to control atomic
interactions with high spatial and temporal resolution.Comment: Significant changes to text and figure presentation to improve
clarity. Extended supplementary material. 4 pages, 4 figures; includes
supplementary material 8 pages, 4 figures. Submitted to Physical Review
Letter
- …