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.
ABSTRACT
We report the discovery of a transient seen in a strongly lensed arc at redshift zs = 1.2567 in Hubble Space Telescope imaging of the Abell 370 galaxy cluster. The transient is detected at ...29.51 ± 0.14 AB mag in a WFC3/UVIS F200LP difference image made using observations from two different epochs, obtained in the framework of the Flashlights programme, and is also visible in the F350LP band (mF350LP ≈ 30.53 ± 0.76 AB mag). The transient is observed on the negative-parity side of the critical curve at a distance of ∼0.6 arcsec from it, greater than previous examples of lensed stars. The large distance from the critical curve yields a significantly smaller macromagnification, but our simulations show that bright, O/B-type supergiants can reach sufficiently high magnifications to be seen at the observed position and magnitude. In addition, the observed transient image is a trailing image with an observer-frame time delay of ∼+0.8 d from its expected counterpart, so that any transient lasting for longer than that should have also been seen on the minima side and is thus excluded. This, together with the blue colour we measure for the transient (mF200LP − mF350LP ≈ −0.3, −1.6 AB), rules out most other transient candidates such as (kilo)novae, for example, and makes a lensed star the prime candidate. Assuming that the transient is indeed a lensed star as suggested, many more such events should be detected in the near future in cluster surveys with the Hubble Space Telescope and JWST.
ABSTRACT
The Reionization Cluster Survey imaged 41 galaxy clusters with the Hubble Space Telescope (HST), in order to detect lensed and high-redshift galaxies. Each cluster was imaged to about 26.5 ...AB mag in three optical and four near-infrared bands, taken in two distinct visits separated by varying time intervals. We make use of the multiple near-infrared epochs to search for transient sources in the cluster fields, with the primary motivation of building statistics for bright caustic crossing events in gravitational arcs. Over the whole sample, we do not find any significant (≳5σ) caustic crossing events, in line with expectations from semi-analytical calculations but in contrast to what may be naively expected from previous detections of some bright events or from deeper transient surveys that do find high rates of such events. Nevertheless, we find six prominent supernova (SN) candidates over the 41 fields: three of them were previously reported and three are new ones reported here for the first time. Out of the six candidates, four are likely core-collapse SNe – three in cluster galaxies, and among which only one was known before, and one slightly behind the cluster at z ∼ 0.6–0.7. The other two are likely Ia – both of them previously known, one probably in a cluster galaxy and one behind it at z ≃ 2. Our study supplies empirical bounds for the rate of caustic crossing events in galaxy cluster fields to typical HST magnitudes, and lays the groundwork for a future SN rate study.
We consider variations of the classical jeep problems： the optimal logistics for a caravan of jeeps which travel together in the desert. The main purpose is to arrange the travels for the one-way ...trip and the round trip of a caravan of jeeps so that the chief jeep visits the farthest destination. Based on the dynamic program principle, the maximum distances for the caravan when only part of the jeeps should return and when all drivers should return are obtained. Some related results such as the efficiency of the abandoned jeeps, and the advantages of more jeeps in the caravan are also presented.
Abstract
A Type Ia supernova (SN) at
z
= 1.78 was discovered in James Webb Space Telescope Near Infrared Camera imaging of the galaxy cluster PLCK G165.7+67.0 (G165;
z
= 0.35). The SN is situated ...1.5–2 kpc from the host-galaxy nucleus and appears in three different locations as a result of gravitational lensing by G165. These data can yield a value for Hubble’s constant using time delays from this multiply imaged SN Ia that we call “SN H0pe.” Over the cluster, we identified 21 image multiplicities, confirmed five of them using the Near-Infrared Spectrograph, and constructed a new lens model that gives a total mass within 600 kpc of (2.6 ± 0.3) × 10
14
M
⊙
. The photometry uncovered a galaxy overdensity coincident with the SN host galaxy. NIRSpec confirmed six member galaxies, four of which surround the SN host galaxy with relative velocity ≲900 km s
−1
and projected physical extent ≲33 kpc. This compact galaxy group is dominated by the SN host galaxy, which has a stellar mass of (5.0 ± 0.1) × 10
11
M
⊙
. The group members have specific star formation rates of 2–260 Gyr
−1
derived from the H
α
-line fluxes corrected for stellar absorption, dust extinction, and slit losses. Another group centered on a strongly lensed dusty star-forming galaxy is at
z
= 2.24. The total (unobscured and obscured) SFR of this second galaxy group is estimated to be (≳ 100
M
⊙
yr
−1
), which translates to a supernova rate of ∼1 SNe yr
−1
, suggesting that regular monitoring of this cluster may yield additional SNe.
The aims of this study were to 1) encapsulate ibuprofen (IBU) and basic fibroblast growth factor (bFGF) in a thermosensitive micellar hydrogel, 2) test the biological properties of this in situ drug ...delivery system, and 3) study the effect of hydrogel in promoting soft tissue healing after implant surgery and its anti-inflammatory function as an early local treatment of peri-implantitis.
A thermosensitive micellar hydrogel was prepared from amphiphilic copolymer poly(ε-caprolactone-co-1,4,8-trioxa 4.6spiro-9-undecanone)-poly(ethylene glycol)-poly(ε-caprolactone-co-1,4,8-trioxa 4.6spiro-9-undecanone) (PECT) nanoparticles and tested in vitro using a scanning electron microscope, rheometer, UV spectrophotometer, HPLC, and transmission electron microscope.
The bFGF + IBU/PECT hydrogel formed a stable, water-dispersible nanoparticle core shell that was injectable at room temperature, hydrogel in situ at body temperature, and provided sustained release of both hydrophilic and hydrophobic drugs. The hydrogel promoted the proliferation and adhesion of human gingival fibroblasts, upregulated the expression of adhesion factors such as vinculin proteins, and showed anti-inflammatory properties.
In situ preparation of IBU-and bFGF-loaded PECT hydrogel represents a promising drug delivery system with the potential to provide early local treatment for peri-implantitis.
The electrosynthesis of poly(3,4-ethylenedithiathiophene) (PEDTT), which is the sulfur analogue of the well-known poly(3,4-ethylenedioxythiophene) (PEDOT), is investigated in green binary solvent ...system of deionized water and anhydrous ethanol (1:1 by volume) contained poly(sodium-p- styrenesulfonate) (PSSNa) as the surfactant and LiClO4.3H2O as supporting electrolyte . The polymer obtained from this medium showed good electrochemical behavior, stability, electrochromic properties and could be partly dissolved in dimethylsulfoxide, tetrahydrofuran, chloroform, etc. Electrochemical impedance studies were performed on Pt/PEDTT/electrolyte system. From the Nyquist plots of the PEDTT film, the electroactivity of the polymer starts to increase from 1.0 V. FT-IR and UV-vis-NIR spectra indicated that the polymerization of monomer occurred mainly at 2,5 position. Cyclic voltammetry and spectroelectrochemistry studies demonstrated that PEDTT can be reversibly oxidized and reduced accompanied by obvious color changes from grass green to golden brown, these properties indicate that the polymer showed favorable electrochromic performance. Fluorescent spectral studies indicated that the polymer was a green-light emitter. TG and DTG analyses showed that the as-formed PEDTT films had good thermal stability.
We report the discovery of two extremely magnified lensed star candidates behind the galaxy cluster MACS J0647.7+015 using recent multiband James Webb Space Telescope (JWST) NIRCam observations. The ...star candidates are seen in a previously known, z (phot) similar or equal to 4.8 dropout giant arc that straddles the critical curve. The candidates lie near the expected critical curve position, but lack clear counter-images on the other side of it, suggesting these are possibly stars undergoing caustic crossings. We present revised lensing models for the cluster, including multiply imaged galaxies newly identified in the JWST data, and use them to estimate background macro-magnifications of at least greater than or similar to 90 and greater than or similar to 50 at the positions of the two candidates, respectively. With these values, we expect effective, caustic-crossing magnifications of similar to10(3)-10(5) for the two star candidates. The spectral energy distributions of the two candidates match well the spectra of B-type stars with best-fit surface temperatures of similar to 10,000 K, and similar to 12,000 K, respectively, and we show that such stars with masses greater than or similar to 20 M (circle dot) and greater than or similar to 50 M (circle dot), respectively, can become sufficiently magnified to be observable. We briefly discuss other alternative explanations and conclude that these objects are likely lensed stars, but also acknowledge that the less-magnified candidate may alternatively reside in a star cluster. These star candidates constitute the second highest-redshift examples to date after Earendel at z (phot) similar or equal to 6.2, establishing further the potential of studying extremely magnified stars at high redshifts with JWST. Planned future observations, including with NIRSpec, will enable a more detailed view of these candidates in the near future.
This study was designed to investigate the effect of 650-nm low-level laser irradiation (LLLI) as an adjunctive treatment of experimental periodontitis. To investigate possible LLLI-mediated ...anti-inflammatory effects, we utilized an experimental periodontitis (EP) rat model and analyzed c-Jun, c-Fos, ICAM-1, and CCL2 gene expressions on PB leukocytes and in the gingival tissue. Total RNA was isolated from the gingivae and peripheral blood (PB) leukocytes of normal, EP, scaling, and root planing (SRP)-treated EP and LLLI + SRP-treated EP rats, and gene expressions were analyzed by real-time PCR. The productions of c-Jun, c-Fos, ICAM-1, and CCL2 in gingivae were analyzed immunohistochemically. Tartrate-resistant acid phosphatase (TRAP) staining was used to determine osteoclast activity in alveolar bone. The c-Jun and ICAM-1 messenger RNA (mRNA) levels were significantly decreased in the EP rat gingival tissue treated by SRP + LLLI than by SRP, the c-Jun, ICAM-1, and c-Fos mRNA levels on PB leukocytes reduced after LLLI treatment but did not show any significant differences in both groups. There was no significant difference in CCL2 mRNA levels on PB leukocytes and in gingivae between the SRP + LLLI and the SRP groups. The c-Fos mRNA levels in gingivae did not show significant difference in both groups. Immunohistochemistry showed that the CCL2, ICAM-1, c-Jun, and c-Fos productions were significantly reduced in rats of the SRP + LLLI group compared with the only SRP group. LLLI significantly decreased the number of osteoclasts as demonstrated by TRAP staining. The 650-nm LLLI might be a useful treatment modality for periodontitis.
After publication of our article 1 we realized that we had not acknowledged that some of the text overlaps with a previous publication 2. We apologize to readers for this error.
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