Cluster Counterparts Research Articles

An extreme ultra-compact X-ray binary in a globular cluster: multiwavelength observations of RZ 2109 explored in a triple system framework

ABSTRACT The globular cluster ultraluminous X-ray source, RZ 2109, is a complex and unique system that has been detected at X-ray, ultraviolet, and optical wavelengths. Based on almost 20 yr of Chandra and XMM–Newton observations, the X-ray luminosity exhibits order of magnitude variability, with the peak flux lasting on the order of a few hours. We perform robust time series analysis on the archival X-ray observations and find that this variability is periodic on a time-scale of 1.3 ± 0.04 d. The source also demonstrates broad [O iii] λ5007 emission, which has been observed since 2004, suggesting a white dwarf donor and therefore an ultra-compact X-ray binary. We present new spectra from 2020 and 2022, marking 18 yr of observed [O iii] emission from this source. Meanwhile, we find that the globular cluster counterpart is unusually bright in the NUV/UVW2 band. Finally, we discuss RZ 2109 in the context of the eccentric Kozai–Lidov mechanism and show that the observed 1.3 d periodicity can be used to place constraints on the tertiary configuration, ranging from 20 min (for a 0.1 M⊙ companion) to approximately 95 min (for a 1 M⊙ companion), if the eccentric Kozai–Lidov mechanism is at the origin of the periodic variability.

On the synergetic effects of cyclic cooperativity in water clusters.

The present study delves into the question of how the strength of a hydrogen bond (HB) common to two or more cyclic HB networks is influenced by the cooperativity contributions (CCs) of these cycles. We employ the molecular tailoring approach-based method to calculate the cyclic CCs in water clusters, Wn (n = 6-20). The energy of an HB in a Wn cluster is estimated by adding the total cyclic CC to its counterpart in the respective dimer. The resulting HB energies closely match their full cluster counterparts, typically within 1.0 kcal mol-1, with substantial CCs of these cyclic networks.

Impact of patient characteristics on innate immune responses and inflammasome activation in ex vivo human lung tissues infected with influenza A virus.

Influenza A virus (IAV) infection poses a persistent global health challenge, necessitating a nuanced grasp of host immune responses for optimal interventions. While the interplay between aging, immunosenescence, and IAV is recognized as key in severe lower respiratory tract infections, the role of specific patient attributes in shaping innate immune reactions and inflammasome activity during IAV infection remains under-investigated. In this study, we utilized an ex vivo infection model of human lung tissues with H3N2 IAV to discern relationships among patient demographics, IAV nucleoprotein (NP) expression, toll-like receptor (TLR) profiles, PD-1/PD-L1 markers, and cytokine production. Our cohort consisted of thirty adult patients who underwent video-assisted thoracoscopic surgery during 2018-2019. Post-surgical lung tissues were exposed to H3N2 IAV for ex vivo infections, and the ensuing immune responses were profiled using flow cytometry. We observed pronounced IAV activity within lung cells, as indicated by marked NP upregulation in both epithelial cells (P = 0.022) and macrophages (P = 0.003) in the IAV-exposed group relative to controls. Notably, interleukin-2 levels correlated with variations in TLR1 expression on epithelial cells and PD-L1 markers on macrophages. Age emerged as a modulating factor, dampening innate immune reactions, as evidenced by reduced interleukin-2 and interferon-γ concentrations (both adjusted P < 0.05). Intriguingly, a subset of participants with pronounced tumor necrosis factor-alpha post-mock infection (Cluster 1) showed attenuated cytokine responses in contrast to their counterparts in Cluster 2 and Cluster 3 (all adjusted P < 0.05). Individuals in Cluster 2, characterized by a low post-mock infection NP expression in macrophages, exhibited reduced variations in both NP and TLR1-3 expressions on these cells and a decreased variation in interleukin-2 secretion in comparison to their Cluster 3 counterparts, who were identified by their elevated NP macrophage expression (all adjusted P < 0.05). Our work elucidates the multifaceted interplay of patient factors, innate immunity, and inflammasome responses in lung tissues subjected to ex vivo H3N2 IAV exposure, reflecting real-world lower respiratory tract infections. While these findings provide a foundation for tailored therapeutic strategies, supplementary studies are requisite for thorough validation and refinement.

The X-ray point source population hosted by globular clusters in the elliptical galaxy NGC 4261

ABSTRACT Utilizing archival Chandra X-ray Observatory data and Hubble Space Telescope globular cluster catalogues, we probe the time-domain properties of the low mass X-ray binary population in the elliptical galaxy NGC 4261. Of the 98 unique X-ray sources identified in this study, 62 sources are within the optical field of view and, of those, 33 per cent are aligned with an optical cluster counterpart. We find twenty X-ray sources coincident with globular clusters; two are previously discovered ultra-luminous X-ray sources (ULXs) and eighteen are low mass X-ray binaries (GCLMXBs) with LX &amp;lt; 1039 erg s−1. ULXs are a heterogeneous class of extremely bright X-ray binaries (LX &amp;gt; 1039 erg s−1) and ULXs located in globular clusters (GCULXs) and may be indicators of black holes. Identifying these unusually X-ray bright sources and measuring their optical properties can provide valuable constraints on the progenitors of gravitational wave sources. We compare observations of these sources to the twenty previously studied GCULXs from five other early-type galaxies, and find that GCULXs in NGC 4261 are of similar colour and luminosity and do not significantly deviate from the rest of the sample in terms of distance from the galaxy centre or X-ray luminosity. Both the GCULX and GCLMXB populations of NGC 4261 show long-term variability; the former may have implications for fast radio bursts originating in globular clusters and the latter will likely introduce additional scatter into the low mass end of GCLMXB X-ray luminosity functions.

Atomic‐level insights into single Pt atom catalysts on CeO2 support

AbstractPrecious Pt metals deposited on reducible CeO2 oxide have been widely used in exhaust gas treatment. However, the high cost of Pt metals is the main barrier that prevents from applying the Pt metals. Therefore, a lot of efforts have been dedicated to reducing the Pt size as small as possible, aiming at maximizing Pt metal utilization efficiency. The smallest ultimate size that Pt metal can be deposited on CeO2 as single atom structures. Furthermore, the supported single Pt atom catalysts enhance catalytic performance and selectivity compared to Pt cluster or Pt particle counterparts. However, the electronic structures of single Pt atom catalysts at the atomic level are a challenge for the experimentalist, leading to a lack of important information in using these catalysts. Here, we aim to figure out the nature of the high thermal stability of single Pt atom catalysts on CeO2 support using density theory functional and compared to experimental data from previous studies. This study will provide useful information on single Pt atom catalysts on CeO2 support aiming at boosting synthesis and applications applying CeO2‐supported Pt.

A local universe model for constrained simulations

ABSTRACT The aim of cosmological simulations is to reproduce the properties of the observed Universe, serving as tools to test structure and galaxy formation models. Constrained simulations of our local cosmological region up to a few hundred $h^{-1}\, \mbox{Mpc}$ , the Local Universe, are designed to reproduce the actual cosmic web of structures as observed. A question that often arises is how to judge the quality of constrained simulations against the observations of the Local Universe. Here we introduce the Local Universe model (LUM), a new methodology, whereby many constrained simulations can be judged and the ‘best’ initial conditions can be identified. By characterizing the Local Universe as a set of rich clusters, the model identifies haloes that serve as simulated counterparts to the observed clusters. Their merit is determined against a null hypothesis, the probability that such a counterpart could be identified in a random, unconstrained simulation. This model is applied to 100 constrained simulations using the Cosmicflows-3 data. Cluster counterparts are found for all constrained simulations, their distribution of separation from the true observed cluster position and their mass distribution are investigated. Lastly, the ‘best’ constrained simulation is selected using the LUM and discussed in more detail.

Structural analysis of brightest cluster galaxies in poor and rich clusters

Studying structural parameters of brightest cluster galaxies (BCGs) provides important clues to understand their formation and evolution. We present the results of the surface brightness profile fitting of 1685 brightest cluster galaxies (BCGs) drawn from the Canada-France-Hawaii Telescope Legacy Survey in the redshift range of 0.1<z<1.0. We fit r-band images of BCGs with a single Sérsic profile. The sample is splitted into two groups based on the host cluster richness to investigate the impact of the environment. Our results suggest that BCGs in rich clusters are statistically larger than their counterparts in poor clusters. We provide best-fit linear regressions for the Kormendy, the logRe−logn, and the size-luminosity relations. In addition, we examined the evolution of the structural parameters, however the BCGs in our sample do not show a significant size change since z∼1.

The stellar populations of quiescent ultra-diffuse galaxies from optical to mid-infrared spectral energy distribution fitting

ABSTRACT We use spectral energy distribution (SED) fitting to place constraints on the stellar population properties of 29 quiescent ultra-diffuse galaxies (UDGs) across different environments. We use the fully Bayesian routine PROSPECTOR coupled with archival data in the optical, near, and mid-infrared from Spitzer and Wide-field Infrared Survey Explorer under the assumption of an exponentially declining star formation history. We recover the stellar mass, age, metallicity, dust content, star formation time scales, and photometric redshifts (photo-zs) of the UDGs studied. Using the mid-infrared data, we probe the existence of dust in UDGs. Although its presence cannot be confirmed, we find that the inclusion of small amounts of dust in the models brings the stellar populations closer to those reported with spectroscopy. Additionally, we fit the redshifts of all galaxies. We find a high accuracy in recovering photo-zs compared to spectroscopy, allowing us to provide new photo-z estimates for three field UDGs with unknown distances. We find evidence of a stellar population dependence on the environment, with quiescent field UDGs being systematically younger than their cluster counterparts. Lastly, we find that all UDGs lie below the mass–metallicity relation for normal dwarf galaxies. Particularly, the globular cluster (GC)-poor UDGs are consistently more metal-rich than GC-rich ones, suggesting that GC-poor UDGs may be puffed-up dwarfs, while most GC-rich UDGs are better explained by a failed galaxy scenario. As a byproduct, we show that two galaxies in our sample, NGC 1052-DF2 and NGC 1052-DF4, share equivalent stellar population properties, with ages consistent with 8 Gyr. This finding supports formation scenarios where the galaxies were formed together.

Plasma-Assisted Dinitrogen Activation via Dual Platinum Cluster Catalysis: A Strategy for Ammonia Synthesis under Mild Conditions

Plasma-Assisted Dinitrogen Activation via Dual Platinum Cluster Catalysis: A Strategy for Ammonia Synthesis under Mild Conditions

Electropolymerization of Metal Clusters Establishing a Versatile Platform for Enhanced Catalysis Performance

AbstractAtomically precise metal clusters are attractive as highly efficient catalysts, but suffer from continuous efficiency deactivation in the catalytic process. Here, we report the development of an efficient strategy that enhances catalytic performance by electropolymerization (EP) of metal clusters into hybrid materials. Based on carbazole ligand protection, three polymerized metal‐cluster hybrid materials, namely Poly‐Cu14cba, Poly‐Cu6Au6cbz and Poly‐Cu6Ag4cbz, were prepared. Compared with isolated metal clusters, metal clusters immobilizing on a biscarbazole network after EP significantly improved their electron‐transfer ability and long‐term recyclability, resulting in higher catalytic performance. As a proof‐of‐concept, Poly‐Cu14cba was evaluated as an electrocatalyst for reducing nitrate (NO3−) to ammonia (NH3), which exhibited ≈4‐fold NH3 yield rate and ≈2‐fold Faraday efficiency enhancement compared to that of Cu14cba with good durability. Similarly, Poly‐Cu6Au6cbz showed 10 times higher photocatalytic efficiency towards chemical warfare simulants degradation than the cluster counterpart.

Electropolymerization of Metal Clusters Establishing a Versatile Platform for Enhanced Catalysis Performance.

Atomically precise metal clusters are attractive as highly efficient catalysts, but suffer from continuous efficiency deactivation in the catalytic process. Here, we report the development of an efficient strategy that enhances catalytic performance by electropolymerization (EP) of metal clusters into hybrid materials. Based on carbazole ligand protection, three polymerized metal-cluster hybrid materials, namely Poly-Cu14 cba, Poly-Cu6 Au6 cbz and Poly-Cu6 Ag4 cbz, were prepared. Compared with isolated metal clusters, metal clusters immobilizing on a biscarbazole network after EP significantly improved their electron-transfer ability and long-term recyclability, resulting in higher catalytic performance. As a proof-of-concept, Poly-Cu14 cba was evaluated as an electrocatalyst for reducing nitrate (NO3 - ) to ammonia (NH3 ), which exhibited ≈4-fold NH3 yield rate and ≈2-fold Faraday efficiency enhancement compared to that of Cu14 cba with good durability. Similarly, Poly-Cu6 Au6 cbz showed 10 times higher photocatalytic efficiency towards chemical warfare simulants degradation than the cluster counterpart.

Increasing energy efficiency of rule-based fuzzy clustering algorithms using CLONALG-M for wireless sensor networks

Because of its efficiency, clustering is used for effective communication in Wireless Sensor Networks (WSNs). In the WSN clustering area, fuzzy approaches are found to be superior to crisp cluster counterparts when the boundaries between clusters are unclear. As a result, many studies have proposed some fuzzy-based solutions to the cluster problem in WSNs. Most rule-based fuzzy clustering systems employ field experts in trial and error processes, identifying and defining fuzzy rules as well as the forms of membership functions at the output; thus, considerable time has been allocated to realize and define these functions. Therefore, it is almost impossible or impractical to achieve a fuzzy system optimally. In this study, we propose a modified clonal selection algorithm (CLONALG-M) to improve the energy efficiency of rule-based fuzzy clustering algorithms. Although some studies in the literature focus on fuzzy optimization in general, to the best of our knowledge, performance improvement of rule-based fuzzy clustering algorithms is not taken into account. The CLONALG-M algorithm based on the Clonal Selection Principle is used to elucidate the basic principles of an adaptive immune system. In this study, we apply this principle to determine the approximate deployment of output-based membership functions that increase the performance of rule-based fuzzy clustering algorithms, whose rule base and shape of membership functions are previously known. Experimental analysis and evaluations of the proposed approach have been performed on selected fuzzy clustering approaches, and obtained results show that our approach performs and adapts well for improving performance of fuzzy output functions.

Modeling chemistry during star formation: water deuteration in dynamic star-forming regions

Context. Recent observations of the HDO/H2O ratio toward protostars in isolated and clustered environments show an apparent dichotomy, where isolated sources show higher D/H ratios than clustered counterparts. Establishing which physical and chemical processes create this differentiation can provide new insights into the chemical evolution of water during star formation and the chemical diversity during the star formation process and in young planetary systems. Aims. We seek to determine to what degree the local cloud environment influences the D/H ratio of water in the hot corinos toward low-mass protostars and establish which physical and chemical conditions can reproduce the observed HDO/H2O and D2O/HDO ratios in hot corinos. Methods. The evolution of water during star formation is modeled using 3D physicochemical models of a dynamic star-forming environment. The physical evolution during the protostellar collapse is described by tracer particles from a 3D MHD simulation of a molecular cloud region. Each particle trajectory is post-processed using RADMC-3D to calculate the temperature and radiation field. The chemical evolution is simulated using a three-phase grain-surface chemistry model and the results are compared with interferometric observations of H2O, HDO, and D2O in hot corinos toward low-mass protostars. Results. The physicochemical model reproduces the observed HDO/H2O and D2O/HDO ratios in hot corinos, but shows no correlation with cloud environment when similar initial conditions are tested. The observed dichotomy in water D/H ratios requires variation in the initial conditions, for example the duration and temperature of the prestellar phase. Reproducing the observed D/H ratios in hot corinos requires a prestellar phase duration t ~ 1−3 Myr and temperatures in the range T ~ 10−20 K prior to collapse. Furthermore, high cosmic-ray ionization rates (ξH2 ~ 10−15 s−1) appear to be incompatible with the observed D/H ratios toward low-mass protostars. Conclusions. This work demonstrates that the observed differentiation between clustered and isolated protostars stems from differences in the molecular cloud or prestellar core conditions and does not arise during the protostellar collapse itself. The observed D/H ratios for water in hot corinos are consistent with chemical inheritance of water, and no resetting during the protostellar collapse, providing a direct link between the prestellar chemistry and the hot corino.

Stellar clustering and orbital architecture of planetary systems

Context. Revealing the mechanisms shaping the architecture of planetary systems is crucial for our understanding of their formation and evolution. In this context, it has been recently proposed that stellar clustering might be the key in shaping the orbital architecture of exoplanets. Aims. The main goal of this work is to explore the factors that shape the orbits of planets. Methods. We performed different statistical tests to compare the properties of planets and their host stars associated with different stellar environments. Results. We used a homogeneous sample of relatively young FGK dwarf stars with radial velocity detected planets and tested the hypothesis that their association to phase space (position-velocity) over-densities (“cluster” stars) and under-densities (“field” stars) impacts the orbital periods of planets. When controlling for the host star properties on a sample of 52 planets orbiting around cluster stars and 15 planets orbiting around field stars, we found no significant difference in the period distribution of planets orbiting these two populations of stars. By considering an extended sample of 73 planets orbiting around cluster stars and 25 planets orbiting field stars, a significant difference in the planetary period distributions emerged. However, the hosts associated with stellar under-densities appeared to be significantly older than their cluster counterparts. This does not allow us to conclude as to whether the planetary architecture is related to age, environment, or both. We further studied a sample of planets orbiting cluster stars to study the mechanism responsible for the shaping of orbits of planets in similar environments. We could not identify a parameter that can unambiguously be responsible for the orbital architecture of massive planets, perhaps, indicating the complexity of the issue. Conclusions. An increased number of planets in clusters and in over-density environments will help to build large and unbiased samples which will then allow to better understand the dominant processes shaping the orbits of planets.

Identification of Cosmic Voids as Massive Cluster Counterparts

Abstract We develop a method to identify cosmic voids from the matter density field by adopting a physically motivated concept that voids are the counterpart of massive clusters. To prove the concept we use a pair of ΛCDM simulations, a reference and its initial density-inverted mirror simulation, and study the relation between the effective size of voids and the mass of corresponding clusters. Galaxy cluster-scale dark matter halos are identified in the Mirror simulation at z = 0 by linking dark matter particles. The void corresponding to each cluster is defined in the Reference simulation as the region occupied by the member particles of the cluster. We study the voids corresponding to the halos more massive than 1013 h −1 M ⊙. We find a power-law scaling relation between the void size and the corresponding cluster mass. Voids with a corresponding cluster mass above 1015 h −1 M ⊙ occupy ∼1% of the total simulated volume, whereas this fraction increases to ∼54% for voids with a corresponding cluster mass above 1013 h −1 M ⊙. It is also found that the density profile of the identified voids follows a universal functional form. Based on these findings, we propose a method to identify cluster-counterpart voids directly from the matter density field without their mirror information by utilizing three parameters such as the smoothing scale, density threshold, and minimum core fraction. We recover voids corresponding to clusters more massive than 3 × 1014 h −1 M ⊙ at a 70%–74% level of completeness and reliability. Our results suggest that we are able to identify voids in a way to associate them with clusters of a particular mass scale.

Weak-lensing clusters from HSC survey first-year data: Mitigating the dilution effect of foreground and cluster-member galaxies

Abstract We present a weak-lensing cluster search using Hyper Suprime-Cam Subaru Strategic Program (HSC survey) first-year data. We pay special attention to the dilution effect of cluster-member and foreground galaxies on weak-lensing signals from clusters of galaxies; we adopt the globally normalized weak-lensing estimator which is least affected by cluster-member galaxies, and we select source galaxies by using photometric redshift information to mitigate the effect of foreground galaxies. We produce six samples of source galaxies with different low-z galaxy cuts, construct weak-lensing mass maps for each source sample, and search for high peaks in the mass maps that cover an effective survey area of ∼120 deg2. We combine six catalogs of high peaks into a sample of cluster candidates which contains 124 high peaks with signal-to-noise ratios greater than five. We cross-match the peak sample with the public optical cluster catalog constructed from the same HSC survey data to identify cluster counterparts of the peaks. We find that 107 out of 124 peaks have matched clusters within 5′ of peak positions. Among them, we define a subsample of 64 secure clusters that we use to examine dilution effects on our weak-lensing cluster search. We find that source samples with low-z galaxy cuts mitigate the dilution effect on weak-lensing signals of high-z clusters ($z \gtrsim 0.3$), and thus combining multiple peak catalogs from different source samples improves the efficiency of weak-lensing cluster searches.

Optical validation and characterisation of Planck PSZ1 sources at the Canary Islands observatories

We report new galaxy clusters previously unknown included in the first Planck Sunyaev–Zeldovich (SZ) sources catalogue, the PSZ1. The results presented here were achieved during the second year of a two-year observational programme, the ITP13, developed at the Roque de los Muchachos Observatory (La Palma, Spain). Using the 2.5 m Isaac Newton telescope, the 3.5 m Telescopio Nazionale Galileo, the 4.2 m William Herschel telescope and the 10.4 m Gran Telescopio Canarias we characterised 75 SZ sources with low SZ significance, SZ S/N &lt; 5.32. We performed deep optical imaging and spectroscopy in order to associate actual galaxy clusters with the SZ Planck source. We adopted robust criteria, based on the 2D spatial distribution, richness, and velocity dispersions to confirm actual optical counterparts up to z &lt; 0.85. The selected systems are confirmed only if they are well aligned with respect to the PSZ1 coordinate and show high richness and high velocity dispersion. In addition, we also inspected the Compton y-maps and SZ significance in order to identify unrealistic detections. Following this procedure, we identify 26 cluster counterparts associated with the SZ emission, which means that only about 35% of the clusters considered in this low S/N PSZ1 subsample are validated. Forty-nine SZ sources (∼65% of this PSZ1 subset) remain unconfirmed. At the end of the ITP13 observational programme, we have studied 256 SZ sources with Dec ≥ −15° (212 of them completely unknown), finding optical counterparts for 152 SZ sources. The ITP13 validation programme has allowed us to update the PSZ1 purity, which is now more refined, increasing from 72% to 83% in the low SZ S/N regime. Our results are consistent with the predicted purity curve for the full PSZ1 catalogue and with the expected fraction of false detections caused by the non-Gaussian noise of foreground signals. We find a strong correlation between the number of unconfirmed sources and the thermal emission of diffuse galactic dust at 857 GHz, thus increasing the fraction of false Planck SZ detections at low galactic latitudes.

Crystal structure of TchmY from Actinoplanes teichomyceticus.

Moenomycin-type antibiotics are phosphoglycolipids that are notable for their unique modes of action and have proven to be useful in animal nutrition. The gene clusters tchm from Actinoplanes teichomyceticus and moe from Streptomyces are among a limited number of known moenomycin-biosynthetic pathways. Most genes in tchm have counterparts in the moe cluster, except for tchmy and tchmz, the functions of which remain unknown. Sequence analysis indicates that TchmY belongs to the isoprenoid enzyme C2-like superfamily and may serve as a prenylcyclase. The enzyme was proposed to be involved in terminal cyclization of the moenocinyl chain in teichomycin, leading to the diumycinol chain of moenomycin isomers. Here, recombinant TchmY protein was expressed in Escherichia coli and its crystal structure was solved by SIRAS. Structural analysis and comparison with other prenylcyclases were performed. The overall fold of TchmY consists of an (α/α)6-barrel, and a potential substrate-binding pocket is found in the central chamber. These results should provide important information regarding the biosynthetic basis of moenomycin antibiotics.

Post-starburst galaxies in different environments

AbstractPost-starburst galaxies (PSBGs) are systems that experienced a burst followed by a rapid quenching of star formation. However, it is still unclear what causes these events and what is the environmental role in the origin of PSBGs. To address this, we analysed sizes, morphologies, ages, and metallicities of PSBGs at 0.05 ≤ z ≤ 0.1 in groups and clusters of galaxies. We find a statistically significant excess of compact PSBGs in groups compared to a control sample of passive galaxies. Satellite PSBGs in groups tend to be more compact compared to their counterparts in clusters. Additionally, the PSBGs in groups have smaller T-type values and are likely to be found in inner group regions compared to PSBGs in clusters. Our results are compatible with dissipative wet merger events being an important mechanism responsible for the origin of PSBGs in groups, but other – less dissipative – processes may be producing PSBGs in cluster environments.

Characterization of a subsample of the Planck SZ source cluster catalogues using optical SDSS DR12 data

Aims. The Planck catalogues of Sunyaev –Zeldovich (SZ) sources, PSZ1 and PSZ2, are the largest catalogues of galaxy clusters selected through their SZ signature in the full sky. In 2013, we started a long-term observational programme at Canary Island observatories with the aim of validating ∼500 unconfirmed SZ sources. In this work we present results of the initial pre-screening of possible cluster counterparts using photometric and spectroscopic data of the Sloan Digital Sky Survey DR12. Our main aim is to identify previously unconfirmed PSZ2 cluster candidates and to contribute in the determination of the actual purity and completeness of Planck SZ source sample. Methods. Using the latest version of the PSZ2 catalogue, we selected all sources overlapping with the SDSS DR12 footprint and without redshift information. We validated these cluster fields following optical criteria (mainly distance with respect to the Planck pointing, magnitude of the brightest cluster galaxy, and cluster richness), and combined these criteria with the profiles of the Planck Compton y-maps. This combined procedure allows for a more robust identification of optical counterparts compared to simply cross-matching with existing SDSS cluster catalogues that have been constructed from earlier SDSS data releases. Results. The sample contains new redshifts for 37 Planck galaxy clusters that were not included in the original release of PSZ2 Planck catalogue. We detect three cases as possible multiple counterparts. We show that a combination of all available information (optical images and profile of SZ signal) can provide correct associations between the observed Planck SZ source and the optically identified cluster. We also show that Planck SZ detection is very sensitive even to high-z (z &gt; 0.5) clusters. In addition, we also present updated spectroscopic information for 34 Planck PSZ1 sources (33 previously photometrically confirmed and 1 new identification).