The Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region (PHATTER). III. The Mass Function of Young Star Clusters in M33

We measure the star cluster mass function for the Local Group galaxy M33. We use the catalog of stellar clusters selected from the Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region (PHATTER) survey. We analyze 711 clusters in M33 with $\rm 7.0$ 3.0 as determined from color-magnitude diagram fits to individual stars. The M33 cluster mass function is best described by a Schechter function with power law slope $\alpha = -2.06^{+0.14}_{-0.13}$, and truncation mass log($M_c/M_{\odot}$) $= 4.24^{+0.16}_{-0.13}$. The data show strong evidence for a high-mass truncation, thus strongly favoring a Schechter function fit over a pure power law. M33's truncation mass is consistent with the previously identified linear trend between $M_c$, and star formation rate surface density, \SigSFR. We also explore the effect that individual cluster mass uncertainties have on derived mass function parameters, and find evidence to suggest that large cluster mass uncertainties have the potential to bias the truncation mass of fitted mass functions on the one sigma level.Comment: 18 pages, 15 figures, 1 table, Accepted to ApJ (February 2, 2022

Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy

We review HB stars in a broad astrophysical context, including both variable and non-variable stars. A reassessment of the Oosterhoff dichotomy is presented, which provides unprecedented detail regarding its origin and systematics. We show that the Oosterhoff dichotomy and the distribution of globular clusters (GCs) in the HB morphology-metallicity plane both exclude, with high statistical significance, the possibility that the Galactic halo may have formed from the accretion of dwarf galaxies resembling present-day Milky Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the second-parameter problem is presented. A technique is proposed to estimate the HB types of extragalactic GCs on the basis of integrated far-UV photometry. The relationship between the absolute V magnitude of the HB at the RR Lyrae level and metallicity, as obtained on the basis of trigonometric parallax measurements for the star RR Lyrae, is also revisited, giving a distance modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are studied. Finally, the conductive opacities used in evolutionary calculations of low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and Space Scienc

Panchromatic Hubble Andromeda Treasury. XVI. Star Cluster Formation Efficiency and the Clustered Fraction of Young Stars

Contains fulltext : 159663.pdf (preprint version ) (Open Access)33 p

Bioinformatic prediction and experimental validation of signals recognised by sensor domains in bacterial receptors: the case of amino acid specific dcache_1AA domain

Resumen del poster presentado en: XIII Reunión del Grupo de Microbiología Molecular de La SEM. Granada, 7-9 septiembre (2022)This work was supported by grants PID2019-103972GA-I00 (to M.A.M.) and PID2020-112612GBI00 (to T.K.) from the Spanish Ministry for Science and Innovation/Agencia Estatal de Investigación 10.13039/501100011033 and grant P18-FR-1621(to T.K.) from the Junta de Andalucía

Amino acid sensor conserved from bacteria to humans

Amino acids are the building blocks of life, and they are also recognized as signals by various receptors in bacteria, archaea, and eukaryotes. Despite their common basic structure, no universal mechanism for amino acid recognition is currently known. Here, we show that a subclass of dCache_1 (double domain found in calcium channels and chemotaxis receptors, family 1), a ubiquitous extracellular sensory domain, contains a simple motif, which recognizes the amino and carboxyl groups of amino acid ligands. We found this motif throughout the Tree of Life. In bacteria and archaea, this motif exclusively binds amino acids, including γ-aminobutyric acid (GABA), and it is present in all major receptor types. In humans, this motif is found in α2δ-subunits of voltage-gated calcium channels that are implicated in neuropathic pain and neurodevelopmental disorders and in a recently characterized CACHD1 protein. Our findings suggest that GABA-derived drugs bind to the same motif in human α2δ-subunits that binds natural GABA ligands in bacterial chemoreceptors. The exact location on the target protein and the mechanism of binding may enable future improvements of drugs targeting pain and neurobiological disorders.This study was supported by Spanish Ministry of Science and Innovation/Agencia Estatal de Investigacion Grants PID2019-103972GA-100 (to M.A.M.) and PID2020-112612GB-100 (to T.K.); Wellcome Trust Grant 206279\Z\17\Z (to A.C.D.); Junta de Andalucia Grant P18-FR-1621 (to T.K.); and NIH Grant 1R35GM131760 (to I.B.Z.). K.M.P. and A.C.D. thank Wendy S. Pratt for molecular biology support