57 research outputs found
The FUor Candidate V582 Aurigae: First Photometric and Spectroscopic Observations
One of the most attractive events in the pre-main sequence evolution is the
FU Orionis (FUor) outburst. Because only a small number of FUor stars have been
detected to date, photometric and spectral studies of every new object are of
great interest. Recently, a new FUor candidate was discovered by Anton Khruslov
- V582 Aur. To confirm the FUors nature of this object we started regular
photometric observations with the telescopes of the National Astronomical
Observatory Rozhen (Bulgaria). A high-resolution spectrum of V582 Aur was
obtained with the 1.93 m telescope in Haute-Provence Observatory (France).Comment: 5 pages, 2 figures, to appear in Bulgarian Astronomical Journa
A history of the Magellanic Clouds and the European exploration of the Southern Hemisphere
The Magellanic Clouds were known before Magellan's voyage exactly 500 years
ago, and were not given that name by Magellan himself or his chronicler Antonio
Pigafetta. They were, of course, already known by local populations in South
America, such as the Mapuche and Tupi-Guaranis. The Portuguese called them
Clouds of the Cape, and scientific circles had long used the name of Nubecula
Minor and Major. We trace how and when the name Magellanic Clouds came into
common usage by following the history of exploration of the southern hemisphere
and the southern sky by European explorers. While the name of Magellan was
quickly associated to the Strait he discovered (within about 20 years only),
the Clouds got their final scientific name only at the end of the 19th century,
when scientists finally abandoned Latin as their communication language.Comment: 20 pages, 9 figures. To appear (in slightly abbreviated form) in the
ESO Messenger 181. Revised (small corrections/additions
The ISO 170um Luminosity Function of Galaxies
We constructed a local luminosity function (LF) of galaxies using a
flux-limited sample (S_170 > 0.195Jy) of 55 galaxies at z < 0.3 taken from the
ISO FIRBACK survey at 170um. The overall shape of the 170-um LF is found to be
different from that of the total 60-um LF (Takeuchi et al. 2003): the bright
end of the LF declines more steeply than that of the 60-um LF. This behavior is
quantitatively similar to the LF of the cool subsample of the IRAS PSCz
galaxies. We also estimated the strength of the evolution of the LF by assuming
the pure luminosity evolution (PLE): L(z) \propto (1+z)^Q. We obtained
Q=5.0^{+2.5}_{-0.5} which is similar to the value obtained by recent Spitzer
observations, in spite of the limited sample size. Then, integrating over the
170-um LF, we obtained the local luminosity density at 170um, \rho_L(170um). A
direct integration of the LF gives \rho_L(170um) = 1.1 \times 10^8 h Lsun
Mpc^{-3}, whilst if we assume a strong PLE with Q=5, the value is 5.2 \times
10^7 h Lsun Mpc^{-3}. This is a considerable contribution to the local FIR
luminosity density. By summing up with other available infrared data, we
obtained the total dust luminosity density in the Local Universe,
\rho_L(dust)=1.1 \times 10^8 h Lsun Mpc^{-3}. Using this value, we estimated
the cosmic star formation rate (SFR) density hidden by dust in the Local
Universe. We obtained \rho_SFR(dust) \simeq 1.1-1.2 h \times 10^{-2} Msun
yr^{-1} Mpc^{-3}$, which means that 58.5% of the star formation is obscured by
dust in the Local Universe.Comment: A&A in pres
The 2-850 micron SED of starforming galaxies
We present preliminary results on a study of the 2--850 micron SEDs of a
sample of 30 FIRBACK galaxies selected at 170 micron. These sources are
representative of the brightest ~10% of the Cosmic Infrared Background. They
are a mixture of mostly local (z<~0.3) starforming galaxies, and a tail of
ULIGs that extend up to z~1, and are likely to be a similar population to faint
SCUBA sources. We use archival Spitzer IRAC and MIPS data to extend the
spectral coverage to the mid-IR regime, resulting in an unprecended (for this
redshift range) census of their infrared SEDs. This allows us to study in far
greater detail this important population linking the near-IR stellar emission
with PAH and thermal dust emission. We do this using a Markov Chain Monte Carlo
method, which easily allows for the inclusion of ~6 free parameters, as well as
an estimate of parameter uncertainties and correlations.Comment: 5 pages, 3 figures. Proceeding for the conference "Starbursts: From
30 Doradus to Lyman Break Galaxies", held in Cambridge (UK) in September,
200
Type IIn Supernova SN 2010jl: Optical Observations for Over 500 Days After Explosion
We present extensive optical observations of a Type IIn supernova (SN) 2010jl
for the first 1.5 years after the discovery. The UBVRI light curves
demonstrated an interesting two-stage evolution during the nebular phase, which
almost flatten out after about 90 days from the optical maximum. SN 2010jl has
one of the highest intrinsic H_alpha luminosity ever recorded for a SN IIn,
especially at late phase, suggesting a strong interaction of SN ejecta with the
dense circumstellar material (CSM) ejected by the progenitor. This is also
indicated by the remarkably strong Balmer lines persisting in the optical
spectra. One interesting spectral evolution about SN 2010jl is the appearance
of asymmetry of the Balmer lines. These lines can be well decomposed into a
narrow component and an intermediate-width component. The intermediate-width
component showed a steady increase in both strength and blueshift with time
until t ~ 400 days after maximum, but it became less blueshifted at t ~ 500
days when the line profile appeared relatively symmetric again. Owing to that a
pure reddening effect will lead to a sudden decline of the light curves and a
progressive blueshift of the spectral lines, we therefore propose that the
asymmetric profiles of H lines seen in SN 2010jl is unlikely due to the
extinction by newly formed dust inside the ejecta, contrary to the explanation
by some early studies. Based on a simple CSM-interaction model, we speculate
that the progenitor of SN 2010jl may suffer a gigantic mass loss (~ 30-50
M_sun) in a few decades before explosion. Considering a slow moving stellar
wind (e.g., ~ 28 km/s) inferred for the preexisting, dense CSM shell and the
extremely high mass-loss rate (1-2 M_sun per yr), we suggest that the
progenitor of SN 2010jl might have experienced a red supergiant stage and
explode finally as a post-red supergiant star with an initial mass above 30-40
M_sun.Comment: 34 pages, 9 figures, accepted for publication in A
Supplement: "Localization and broadband follow-up of the gravitational-wave transient GW150914" (2016, ApJL, 826, L13)
This Supplement provides supporting material for Abbott et al. (2016a). We briefly summarize past electromagnetic (EM) follow-up efforts as well as the organization and policy of the current EM follow-up program. We compare the four probability sky maps produced for the gravitational-wave transient GW150914, and provide additional details of the EM follow-up observations that were performed in the different bands
Multi-messenger observations of a binary neutron star merger
On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta
Localization and broadband follow-up of the gravitational-wave transient GW150914
A gravitational-wave (GW) transient was identified in data recorded by the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) detectors on 2015 September 14. The event, initially designated G184098 and later given the name GW150914, is described in detail elsewhere. By prior arrangement, preliminary estimates of the time, significance, and sky location of the event were shared with 63 teams of observers covering radio, optical, near-infrared, X-ray, and gamma-ray wavelengths with ground- and space-based facilities. In this Letter we describe the low-latency analysis of the GW data and present the sky localization of the first observed compact binary merger. We summarize the follow-up observations reported by 25 teams via private Gamma-ray Coordinates Network circulars, giving an overview of the participating facilities, the GW sky localization coverage, the timeline, and depth of the observations. As this event turned out to be a binary black hole merger, there is little expectation of a detectable electromagnetic (EM) signature. Nevertheless, this first broadband campaign to search for a counterpart of an Advanced LIGO source represents a milestone and highlights the broad capabilities of the transient astronomy community and the observing strategies that have been developed to pursue neutron star binary merger events. Detailed investigations of the EM data and results of the EM follow-up campaign are being disseminated in papers by the individual teams
Localization and Broadband Follow-up of the Gravitational-wave Transient GW150914
A gravitational-wave (GW) transient was identified in data recorded by
the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO)
detectors on 2015 September 14. The event, initially designated G184098
and later given the name GW150914, is described in detail elsewhere. By
prior arrangement, preliminary estimates of the time, significance, and
sky location of the event were shared with 63 teams of observers
covering radio, optical, near-infrared, X-ray, and gamma-ray wavelengths
with ground- and space-based facilities. In this Letter we describe the
low-latency analysis of the GW data and present the sky localization of
the first observed compact binary merger. We summarize the follow-up
observations reported by 25 teams via private Gamma-ray Coordinates
Network circulars, giving an overview of the participating facilities,
the GW sky localization coverage, the timeline, and depth of the
observations. As this event turned out to be a binary black hole merger,
there is little expectation of a detectable electromagnetic (EM)
signature. Nevertheless, this first broadband campaign to search for a
counterpart of an Advanced LIGO source represents a milestone and
highlights the broad capabilities of the transient astronomy community
and the observing strategies that have been developed to pursue neutron
star binary merger events. Detailed investigations of the EM data and
results of the EM follow-up campaign are being disseminated in papers by
the individual teams.
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