We present the first and deepest Australia Telescope Compact Array radio continuum images of the Honeycomb Nebula at 2000 and 5500MHz solely from archival data. The resolutions of these images are ...3:6 x 2:8 arcsec2 and 1:3 x 1:2 arcsec2 at 2000 and 5500 MHz. We find an average radio spectral index for the remnant of -0:76?0:07. Polarisation maps at 5500MHz reveal an average fractional polarisation of 25 ? 5% with a maximum value of 95 ? 16. We estimate the equipartition field for Honeycomb Nebula of 48 ? 5 ?G, with an estimated minimum energy of Emin = 3 x 1049 erg. The estimated surface brightness, ?1 GHz, is 30 x 10-20Wm-2 Hz-1 sr-1; applying the ?-D relation suggests this supernova remnant is expanding into a low-density environment. Finally, using Hi data, we can support the idea that the Honeycomb Nebula exploded inside a low-density wind cavity. We suggest that this remnant is likely to be between late free expansion stage and early Sedov phase of evolution and expanding into a low-density medium.
Science with the Cherenkov Telescope Array The Cta Consortium, The Cta Consortium
The Astrophysical journal. Supplement series,
01/2019, Letnik:
240, Številka:
2
eBook, Journal Article, Book
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This book summarizes the science to be carried out by the upcoming Cherenkov Telescope Array, a major ground-based gamma-ray observatory that will be constructed over the next six to eight years. The ...major scientific themes, as well as core program of key science projects, have been developed by the CTA Consortium, a collaboration of scientists from many institutions worldwide. CTA will be the major facility in high-energy and very high-energy photon astronomy over the next decade and beyond. CTA will have capabilities well beyond past and present observatories. Thus, CTA's science program is expected to be rich and broad and will complement other major multiwavelength and multimessenger facilities. This book is intended to be the primary resource for the science case for CTA and it thus will be of great interest to the broader physics and astronomy communities. The electronic version (e-book) is available in open access.
Desde 2017, el Instituto de Astronomía de a Academia de Ciencias Rusa (Rusia) y el Instituto de Geofísica y Astronomía (Cuba) han estado implementando un proyecto internacional conjunto con el ...objetivo de construir una red global de telescopios (ópticos. El primer telescopio robótico de 20 cm de esta red opera desde 2021 en La Habana. La construcción del segundo telescopio de 50 cm has estado llevándose a cabo desde 2023 y se espera instalar en 2025 cerca de Kislovodsk (Rusia). De acuerdo con el plan actual, un tercer telescopio de 1 m será instalado en 2030 en Valle de Picadura (Cuba). En la presente contribución, se describen los principales parámetros y el equipamiento científico del telescopio de 50 cm, y se discute su papel en la red global de telescopios ruso-cubanos.
SKA (Square Kilometre Array), the largest and most powerful interferometric array of radio telescopes in the world in the 50 MHz to 15 GHz frequency range is currently under construction. Its ...unprecedented performance will revolutionize modern astrophysics starting from the next decade. The technological radioastronomical group at the INAF-Arcetri Astrophysical Observatory is actively involved in the design, development and validation of SKA-Low, the low-frequency (50-350 MHz) component of SKA. Keywords. SKA, radio telescopes, aperture arrays, calibration. SKA (Square Kilometre Array), la più estesa e potente rete interferometrica di radiotelescopi al mondo nella banda di frequenze da 50 MHz a 15 GHz, è attualmente in fase di costruzione. A partire dal prossimo decennio, le prestazioni senza precedenti di SKA rivoluzioneranno l'astrofisica moderna. Il gruppo tecnologico di radioastronomia dell'Osservatorio Astrofisico di Arcetri (INAF) contribuisce attivamente alle fasi di design, sviluppo e validazione di SKA-Low, la componente di SKA operante a bassa frequenza (50-350 MHz). Parole chiave. SKA, radiotelescopi, array di aperture, calibrazione.
The TRAPPIST-1 system is remarkable for its seven planets that are similar in size, mass, density and stellar heating to the rocky planets Venus, Earth and Mars in the Solar System
. All the ...TRAPPIST-1 planets have been observed with transmission spectroscopy using the Hubble or Spitzer space telescopes, but no atmospheric features have been detected or strongly constrained
. TRAPPIST-1 b is the closest planet to the M-dwarf star of the system, and it receives four times as much radiation as Earth receives from the Sun. This relatively large amount of stellar heating suggests that its thermal emission may be measurable. Here we present photometric secondary eclipse observations of the Earth-sized exoplanet TRAPPIST-1 b using the F1500W filter of the mid-infrared instrument on the James Webb Space Telescope (JWST). We detect the secondary eclipses in five separate observations with 8.7σ confidence when all data are combined. These measurements are most consistent with re-radiation of the incident flux of the TRAPPIST-1 star from only the dayside hemisphere of the planet. The most straightforward interpretation is that there is little or no planetary atmosphere redistributing radiation from the host star and also no detectable atmospheric absorption of carbon dioxide (CO
) or other species.
The launch of the
James Webb Space Telescope
(JWST) in late 2021 marks a new start for studies of galaxy formation at high redshift (
z
6) during the era of cosmic reionization. JWST can capture ...sensitive, high-resolution images and multiobject spectroscopy in the IR that will transform our view of galaxy formation during the first billion years of cosmic history. This review summarizes our current knowledge of the role of galaxies in reionizing intergalactic hydrogen ahead of JWST, achieved through observations with the
Hubble Space Telescope
and ground-based facilities including Keck, the Very Large Telescope, Subaru, and the Atacama Large Millimeter/Submillimeter Array. We identify outstanding questions in the field that JWST can address during its mission lifetime, including with the planned JWST Cycle 1 programs. These findings include the following:
Surveys with JWST have sufficient sensitivity and area to complete the census of galaxy formation at the current redshift frontier (
z
∼ 8-10).
Rest-frame optical spectroscopy with JWST of galaxies will newly enable measures of star-formation rate, metallicity, and ionization at
z
∼ 8-9, allowing for the astrophysics of early galaxies to be constrained.
The presence of evolved stellar populations at
z
∼ 8-10 can be definitively tested by JWST, which would provide evidence of star formation out to
z
∼ 15.
Abstract
The PHANGS program is building the first data set to enable the multiphase, multiscale study of star formation across the nearby spiral galaxy population. This effort is enabled by large ...survey programs with the Atacama Large Millimeter/submillimeter Array (ALMA), MUSE on the Very Large Telescope, and the Hubble Space Telescope (HST), with which we have obtained CO(2–1) imaging, optical spectroscopic mapping, and high-resolution UV–optical imaging, respectively. Here, we present PHANGS-HST, which has obtained NUV–
U
–
B
–
V
–
I
imaging of the disks of 38 spiral galaxies at distances of 4–23 Mpc, and parallel
V
- and
I
-band imaging of their halos, to provide a census of tens of thousands of compact star clusters and multiscale stellar associations. The combination of HST, ALMA, and VLT/MUSE observations will yield an unprecedented joint catalog of the observed and physical properties of ∼100,000 star clusters, associations, H
ii
regions, and molecular clouds. With these basic units of star formation, PHANGS will systematically chart the evolutionary cycling between gas and stars across a diversity of galactic environments found in nearby galaxies. We discuss the design of the PHANGS-HST survey and provide an overview of the HST data processing pipeline and first results. We highlight new methods for selecting star cluster candidates, morphological classification of candidates with convolutional neural networks, and identification of stellar associations over a range of physical scales with a watershed algorithm. We describe the cross-observatory imaging, catalogs, and software products to be released. The PHANGS high-level science products will seed a broad range of investigations, in particular, the study of embedded stellar populations and dust with the James Webb Space Telescope, for which a PHANGS Cycle 1 Treasury program to obtain eight-band 2–21
μ
m imaging has been approved.
The observations of the M87 jet with the STIS instrument mounted on board the Hubble Space Telescope revealed that an outburst originating in the HST-1 knot occurred. Measuring the dimensions of the ...outburst in the epochs between 2001 July 30 and 2003 July 27 and correcting for optical illusion an expansion velocity v/c = 0.99893 + or - 0.00007 is found. However, the relativistic model fails to correctly predict the dimensions of the source and the outburst brightness. For this reason, as the apparent motion suggests, a superluminal mechanical model where even the light rays travel faster than light is introduced. By applying this model to correct for optical illusion an expansion velocity v/c = 21.8 + or - 0.7 is found along with reasonable source dimensions and brightness. This result, the study of the apparent motion of features in the M87 jet and the time-of-flight measurements of muonic neutrinos seem to confirm the possibility to travel faster than light. That does not imply a refusal of special relativity. Instead only the common interpretations of it are refused. Without them, we will also see that the so-called twin paradox does not have any reason to exist. c 2019 Physics Essays Publication. http://dx.doi.org/10.4006/0836-1398-32.L48
Abstract
We conduct a comprehensive study on dropout galaxy candidates at
z
∼ 9–16 using the first 90 arcmin
2
James Webb Space Telescope (JWST) Near Infrared Camera images taken by the early release ...observations (ERO) and early release science programs. With the JWST simulation images, we find that a number of foreground interlopers are selected with a weak photo-
z
determination (Δ
χ
2
> 4). We thus carefully apply a secure photo
-z
selection criterion (Δ
χ
2
> 9) and conventional color criteria with confirmations of the ERO Near Infrared Spectrograph spectroscopic redshifts, and obtain a total of 23 dropout galaxies at
z
∼ 9–16, including two candidates at
z
phot
=
16.25
−
0.46
+
0.24
and
16.41
−
0.55
+
0.66
. We perform thorough comparisons of dropout galaxies found in our work with recent JWST studies, and conclude that our galaxy sample is reliable enough for statistical analyses. We derive the UV luminosity functions at
z
∼ 9–16, and confirm that our UV luminosity functions at
z
∼ 9 and 12 agree with those determined by other Hubble Space Telescope and JWST studies. The cosmic star formation rate (SFR) density decreases from
z
∼ 9 to 12, and perhaps to 16, but the densities at
z
∼ 12–16 are higher than the constant star formation efficiency model. Interestingly, there are six bright galaxy candidates at
z
∼ 10–16 with
M
UV
< −19.5 mag and
M
*
∼ 10
8−9
M
⊙
. Because a majority (∼80%) of these galaxies show no signatures of active galactic nuclei in their morphologies, the high cosmic SFR densities and the existence of these UV-luminous galaxies are explained by the lack of suppression of star formation by the UV background radiation at the pre-reionization epoch and/or an efficient UV radiation production by a top-heavy initial mass function with Population III–like star formation.
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