We present JWST/NIRSpec prism spectroscopy of MACS0647-JD, the triply-lensed
$z \sim 11$ candidate discovered in HST imaging and spatially resolved by JWST
imaging into two components A and B. ...Spectroscopy of component A yields a
spectroscopic redshift $z=10.17$ based on 7 detected emission lines: CIII
$\lambda\lambda$1907,1909, OII $\lambda$3727, NeIII $\lambda$3869, NeIII
$\lambda$3968, H$\delta$ $\lambda$4101, H$\gamma$ $\lambda$4340, and OIII
$\lambda$4363. These are the second-most distant detections of these emission
lines to date, in a galaxy observed just 460 million years after the Big Bang.
Based on observed and extrapolated line flux ratios we derive a gas-phase
metallicity $Z =$ log(O/H) = $7.5 - 8.0$, or $(0.06 - 0.2)$ $Z_\odot$,
ionization parameter log($U$) $\sim -1.9\pm0.2$, and an ionizing photon
production efficiency ${\rm log}(\xi_{\rm ion})=25.2\pm0.2\,$erg$^{-1}$ Hz. The
spectrum has a softened Lyman-$\alpha$ break, evidence for a strong Ly$\alpha$
damping wing, suggesting that MACS0647-JD was unable to ionize its surroundings
beyond its immediate vicinity ($R_{\text{HII}} \ll 1$ pMpc). The Ly$\alpha$
damping wing also suppresses the F150W photometry, explaining the slightly
overestimated photometric redshift $z = 10.6 \pm 0.3$. MACS0647-JD has a
stellar mass log($M/M_\odot$) = $8.1 \pm 0.3$, including $\sim$ 6$\times 10^7
M_\odot$ in component A, most of which formed recently (within $\sim$ 20 Myr)
with a star formation rate $2\pm1 M_\odot$ / yr, all within an effective radius
$70\pm24\,$pc. The smaller component B ($r \sim 20$) pc is likely older
($\sim$100 Myr) with more dust ($A_V \sim 0.1$ mag), as found previously.
Spectroscopy of a fainter companion galaxy C separated by a distance of \about\
3$\,$kpc reveals a Lyman break consistent with $z = 10.17$. MACS0647-JD is
likely the most distant galaxy merger known.
Massive colliding-wind binaries that host a Wolf-Rayet (WR) star present a potentially important source of dust and chemical enrichment in the interstellar medium (ISM). However, the chemical ...composition and survival of dust formed from such systems is not well understood. The carbon-rich WR (WC) binary WR~140 presents an ideal astrophysical laboratory for investigating these questions given its well-defined orbital period and predictable dust-formation episodes every 7.93 years around periastron passage. We present observations from our Early Release Science program (ERS1349) with the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) Medium-Resolution Spectrometer (MRS) and Imager that reveal the spectral and spatial signatures of nested circumstellar dust shells around WR~140. MIRI MRS spectroscopy of the second dust shell and Imager detections of over 17 shells formed throughout the past \(\gtrsim130\) years confirm the survival of carbonaceous dust grains from WR~140 that are likely carriers of "unidentified infrared" (UIR)-band features at 6.4 and 7.7 \(\mu\)m. The observations indicate that dust-forming WC binaries can enrich the ISM with organic compounds and carbonaceous dust.
MACS0647$-$JD is a triply-lensed $z\sim11$ galaxy originally discovered with
the Hubble Space Telescope. Here we report new JWST imaging, which clearly
resolves MACS0647$-$JD as having two components ...that are either merging
galaxies or stellar complexes within a single galaxy. Both are very small, with
stellar masses $\sim10^8\,M_\odot$ and radii $r<100\,\rm pc$. The brighter
larger component "A" is intrinsically very blue ($\beta\sim-2.6$), likely due
to very recent star formation and no dust, and is spatially extended with an
effective radius $\sim70\,\rm pc$. The smaller component "B" appears redder
($\beta\sim-2$), likely because it is older ($100-200\,\rm Myr$) with mild dust
extinction ($A_V\sim0.1\,\rm mag$), and a smaller radius $\sim20\,\rm pc$. We
identify galaxies with similar colors in a high-redshift simulation, finding
their star formation histories to be out of phase. With an estimated stellar
mass ratio of roughly 2:1 and physical projected separation $\sim400\,\rm pc$,
we may be witnessing a galaxy merger 400 million years after the Big Bang. We
also identify a candidate companion galaxy C $\sim3\,{\rm kpc}$ away, likely
destined to merge with galaxies A and B. The combined light from galaxies A+B
is magnified by factors of $\sim$8, 5, and 2 in three lensed images JD1, 2, and
3 with F356W fluxes $\sim322$, $203$, $86\,\rm nJy$ (AB mag 25.1, 25.6, 26.6).
MACS0647$-$JD is significantly brighter than other galaxies recently discovered
at similar redshifts with JWST. Without magnification, it would have AB mag
27.3 ($M_{UV}=-20.4$). With a high confidence level, we obtain a photometric
redshift of $z=10.6\pm0.3$ based on photometry measured in 6 NIRCam filters
spanning $1-5\rm\mu m$, out to $4300\,\r{A}$ rest-frame. JWST NIRSpec
observations planned for January 2023 will deliver a spectroscopic redshift and
a more detailed study of the physical properties of MACS0647$-$JD.
The scientific community has avoided using tissue samples from patients that have been exposed to systemic chemotherapy to infer the genomic landscape of a given cancer. Esophageal adenocarcinoma is ...a heterogeneous, chemoresistant tumor for which the availability and size of pretreatment endoscopic samples are limiting. This study compares whole-genome sequencing data obtained from chemo-naive and chemo-treated samples. The quality of whole-genomic sequencing data is comparable across all samples regardless of chemotherapy status. Inclusion of samples collected post-chemotherapy increased the proportion of late-stage tumors. When comparing matched pre- and post-chemotherapy samples from 10 cases, the mutational signatures, copy number, and SNV mutational profiles reflect the expected heterogeneity in this disease. Analysis of SNVs in relation to allele-specific copy-number changes pinpoints the common ancestor to a point prior to chemotherapy. For cases in which pre- and post-chemotherapy samples do show substantial differences, the timing of the divergence is near-synchronous with endoreduplication. Comparison across a large prospective cohort (62 treatment-naive, 58 chemotherapy-treated samples) reveals no significant differences in the overall mutation rate, mutation signatures, specific recurrent point mutations, or copy-number events in respect to chemotherapy status. In conclusion, whole-genome sequencing of samples obtained following neoadjuvant chemotherapy is representative of the genomic landscape of esophageal adenocarcinoma. Excluding these samples reduces the material available for cataloging and introduces a bias toward the earlier stages of cancer.
We present JWST/NIRSpec prism spectroscopy of MACS0647-JD, the triply-lensed \(z \sim 11\) candidate discovered in HST imaging and spatially resolved by JWST imaging into two components A and B. ...Spectroscopy of component A yields a spectroscopic redshift \(z=10.17\) based on 7 detected emission lines: CIII \(\lambda\lambda\)1907,1909, OII \(\lambda\)3727, NeIII \(\lambda\)3869, NeIII \(\lambda\)3968, H\(\delta\) \(\lambda\)4101, H\(\gamma\) \(\lambda\)4340, and OIII \(\lambda\)4363. These are the second-most distant detections of these emission lines to date, in a galaxy observed just 460 million years after the Big Bang. Based on observed and extrapolated line flux ratios we derive a gas-phase metallicity \(Z =\) log(O/H) = \(7.5 - 8.0\), or \((0.06 - 0.2)\) \(Z_\odot\), ionization parameter log(\(U\)) \(\sim -1.9\pm0.2\), and an ionizing photon production efficiency \({\rm log}(\xi_{\rm ion})=25.2\pm0.2\,\)erg\(^{-1}\) Hz. The spectrum has a softened Lyman-\(\alpha\) break, evidence for a strong Ly\(\alpha\) damping wing, suggesting that MACS0647-JD was unable to ionize its surroundings beyond its immediate vicinity (\(R_{\text{HII}} \ll 1\) pMpc). The Ly\(\alpha\) damping wing also suppresses the F150W photometry, explaining the slightly overestimated photometric redshift \(z = 10.6 \pm 0.3\). MACS0647-JD has a stellar mass log(\(M/M_\odot\)) = \(8.1 \pm 0.3\), including \(\sim\) 6\(\times 10^7 M_\odot\) in component A, most of which formed recently (within \(\sim\) 20 Myr) with a star formation rate \(2\pm1 M_\odot\) / yr, all within an effective radius \(70\pm24\,\)pc. The smaller component B (\(r \sim 20\)) pc is likely older (\(\sim\)100 Myr) with more dust (\(A_V \sim 0.1\) mag), as found previously. Spectroscopy of a fainter companion galaxy C separated by a distance of \about\ 3\(\,\)kpc reveals a Lyman break consistent with \(z = 10.17\). MACS0647-JD is likely the most distant galaxy merger known.
Abstract
The gravitationally lensed star WHL 0137–LS, nicknamed Earendel, was identified with a photometric redshift
z
phot
= 6.2 ± 0.1 based on images taken with the Hubble Space Telescope. Here we ...present James Webb Space Telescope (JWST) Near Infrared Camera images of Earendel in eight filters spanning 0.8–5.0
μ
m. In these higher-resolution images, Earendel remains a single unresolved point source on the lensing critical curve, increasing the lower limit on the lensing magnification to
μ
> 4000 and restricting the source plane radius further to
r
< 0.02 pc, or ∼4000 au. These new observations strengthen the conclusion that Earendel is best explained by an individual star or multiple star system and support the previous photometric redshift estimate. Fitting grids of stellar spectra to our photometry yields a stellar temperature of
T
eff
≃ 13,000–16,000 K, assuming the light is dominated by a single star. The delensed bolometric luminosity in this case ranges from
log
(
L
)
=
5.8
to 6.6
L
⊙
, which is in the range where one expects luminous blue variable stars. Follow-up observations, including JWST NIRSpec scheduled for late 2022, are needed to further unravel the nature of this object, which presents a unique opportunity to study massive stars in the first billion years of the universe.
We present JWST/NIRSpec observations of a highly magnified star candidate at a photometric redshift of \(z_{\mathrm{phot}}\simeq4.8\), previously detected in JWST/NIRCam imaging of the strong lensing ...(SL) cluster MACS J0647+7015 (\(z=0.591\)). The spectroscopic observation allows us to precisely measure the redshift of the host arc at \(z_{\mathrm{spec}}=4.758\pm0.004\), and the star's spectrum displays clear Lyman- and Balmer-breaks commensurate with this redshift. A fit to the spectrum suggests a B-type super-giant star of surface temperature \(T_{\mathrm{eff,B}}\simeq15000\) K with either a redder F-type companion (\(T_{\mathrm{eff,F}}\simeq6250\)K) or significant dust attenuation (\(A_V\simeq0.82\)) along the line of sight. We also investigate the possibility that this object is a magnified young globular cluster rather than a single star. We show that the spectrum is in principle consistent with a star cluster, which could also accommodate the lack of flux variability between the two epochs. However, the lack of a counter image and the strong upper limit on the size of the object from lensing symmetry, \(r\lesssim0.5\) pc, could indicate that this scenario is somewhat less likely -- albeit not completely ruled out by the current data. The presented spectrum seen at a time when the Universe was only \(\sim1.2\) Gyr old showcases the ability of JWST to study early stars through extreme lensing.
ABSTRACT
We present JWST/NIRSpec observations of a highly magnified star candidate at a photometric redshift of zphot ≃ 4.8, previously detected in JWST/NIRCam imaging of the strong lensing (SL) ...cluster MACS J0647+7015 (z = 0.591). The spectroscopic observation allows us to precisely measure the redshift of the host arc at zspec = 4.758 ± 0.004, and the star’s spectrum displays clear Lyman- and Balmer-breaks commensurate with this redshift. A fit to the spectrum suggests a B-type super-giant star of surface temperature $T_{\mathrm{eff,B}}\simeq 15\, 000$ K with either a redder F-type companion ($T_{\mathrm{eff,F}}\simeq 6\, 250$ K) or significant dust attenuation (AV ≃ 0.82) along the line of sight. We also investigate the possibility that this object is a magnified young globular cluster rather than a single star. We show that the spectrum is in principle consistent with a star cluster, which could also accommodate the lack of flux variability between the two epochs. However, the lack of a counter image and the strong upper limit on the size of the object from lensing symmetry, r ≲ 0.5 pc, could indicate that this scenario is somewhat less likely – albeit not completely ruled out by the current data. The presented spectrum seen at a time when the Universe was only ∼1.2 Gyr old showcases the ability of JWST to study early stars through extreme lensing.
MACS0647\(-\)JD is a triply-lensed \(z\sim11\) galaxy originally discovered with the Hubble Space Telescope. Here we report new JWST imaging, which clearly resolves MACS0647\(-\)JD as having two ...components that are either merging galaxies or stellar complexes within a single galaxy. Both are very small, with stellar masses \(\sim10^8\,M_\odot\) and radii \(r<100\,\rm pc\). The brighter larger component "A" is intrinsically very blue (\(\beta\sim-2.6\)), likely due to very recent star formation and no dust, and is spatially extended with an effective radius \(\sim70\,\rm pc\). The smaller component "B" appears redder (\(\beta\sim-2\)), likely because it is older (\(100-200\,\rm Myr\)) with mild dust extinction (\(A_V\sim0.1\,\rm mag\)), and a smaller radius \(\sim20\,\rm pc\). We identify galaxies with similar colors in a high-redshift simulation, finding their star formation histories to be out of phase. With an estimated stellar mass ratio of roughly 2:1 and physical projected separation \(\sim400\,\rm pc\), we may be witnessing a galaxy merger 400 million years after the Big Bang. We also identify a candidate companion galaxy C \(\sim3\,{\rm kpc}\) away, likely destined to merge with galaxies A and B. The combined light from galaxies A+B is magnified by factors of \(\sim\)8, 5, and 2 in three lensed images JD1, 2, and 3 with F356W fluxes \(\sim322\), \(203\), \(86\,\rm nJy\) (AB mag 25.1, 25.6, 26.6). MACS0647\(-\)JD is significantly brighter than other galaxies recently discovered at similar redshifts with JWST. Without magnification, it would have AB mag 27.3 (\(M_{UV}=-20.4\)). With a high confidence level, we obtain a photometric redshift of \(z=10.6\pm0.3\) based on photometry measured in 6 NIRCam filters spanning \(1-5\rm\mu m\), out to \(4300\,Å\) rest-frame. JWST NIRSpec observations planned for January 2023 will deliver a spectroscopic redshift and a more detailed study of the physical properties of MACS0647\(-\)JD.
•Termites are commonly differentiated into feeding and building groups.•Sheeting properties are mainly explained by the properties of the environment.•Building strategy better explains sheeting ...properties.•Redefining groups using a trait-based approach is proposed as perspective.
Termites are key soil bioturbators in tropical ecosystems. Apart from mound nests constructed by some advanced lineages, most of the species use their faeces, oral secretions, debris, or soil aggregates to protect themselves from predators and desiccation when they go out to forage. Although this soil ‘sheeting’ is considered to play a key role in soil functioning, the properties of this termite-made material has been poorly studied. The few available data showed that sheeting properties are highly variable with positive, neutral or negative impacts on soil C and clay content, and consequently on soil aggregate stability. Therefore, the objective of this study was to determine the factors controlling the physical (particle size fractions and structural stability) and chemical (pH, electrical conductivity and carbon content) properties of soil sheeting produced by termite species encompassing all feeding and building categories using a dataset representative of an important diversity of biotopes coming from 21 countries from all continents colonized by termites. We showed that sheeting properties were explained by the properties of their environment, and especially by those of the bulk soil (linear relationships), followed in a lesser extent by the mean annual precipitation and biotope. Classic hypotheses related to termite feeding and building strategies were not hold by our analysis. However, the distinction of termites into fungus-growing and non-fungus growing species was useful when differentiating the impact of termites on soil electrical conductivity, C content, and structural stability. The large variability observed suggests the need to redefine termite functional groups based on their impacts on soil properties using a trait-based approach from morphological, anatomical and/or physiological traits.
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