scholarly journals Long-period variables and carbon stars in the Galactic Bulge

1993 ◽  
Vol 153 ◽  
pp. 39-56 ◽  
Author(s):  
Patricia Whitelock
Keyword(s):  
Globular Clusters ◽  
Galactic Bulge ◽  
Carbon Stars ◽  
Instability Strip ◽  
Long Period ◽  
Wide Range ◽  
Evolutionary Phase ◽  
Binary Evolution ◽  
M Stars ◽  
Different Parts

The review covers the properties of red variables in globular clusters and the Galactic Bulge. Details are given of our current understanding of the Mira evolutionary phase. There is evidence that Miras in the LMC and the Bulge occupy different parts of the instability strip but obey the same PLC relation. The Bulge contains at least 2 × 104 Miras of which 100 or so have luminosities in excess of Mbol = — 5 mag. The Mira phase lasts more than 105 yr. These objects originate from stars with a wide range of metallicity, but it is currently unclear if the most metal-rich stars reach the top of the AGB to become Miras. Preliminary data suggest that the distribution of the Miras along the minor axis of the Bulge is different from that of the late-M stars but similar to the 2.4 μm luminosity.Our knowledge of the Bulge carbon stars is briefly reviewed. It is suggested that, by analogy with the carbon-rich dwarfs, these stars are probably best understood as the products of binary evolution.

Carbon Abundances in Planetary Nebulae in the Galactic Bulge

1984 ◽  
Vol 5 (4) ◽  
pp. 535-537
Author(s):  
B. Louise Webster
Keyword(s):  
Globular Clusters ◽  
Planetary Nebulae ◽  
Open Clusters ◽  
Red Giants ◽  
Galactic Bulge ◽  
Long Period ◽  
Long Period Variables ◽  
Galactic Globular Clusters ◽  
The Masses ◽  
K Giants

The galactic nuclear bulge is a well defined population, but it is one that is relatively difficult to study in detail because its members never stray into the solar vicinity and they are both distant and obscured. Mould (1982) has summarized much of our knowledge of the masses and composition of stars in the bulge. The red giants resemble those in metal-rich old open clusters and the late M giants are either younger than galactic globular clusters or super-metal-rich or both. Whitford and Rich (1983) have demonstrated the existence of K-giants that are super-metal-rich in iron and Wood and Bessell (1983) have interpreted the properties of a sample of long period variables in the bulge as those of a young, super-metal-rich population.

scholarly journals The Blanco DECam bulge survey. I. The survey description and early results

2020 ◽  
Vol 499 (2) ◽  
pp. 2340-2356
Author(s):  
R Michael Rich ◽  
Christian I Johnson ◽  
Michael Young ◽  
Iulia T Simion ◽  
William I Clarkson ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Massive Stars ◽  
The Sun ◽  
Horizontal Branch ◽  
Galactic Bulge ◽  
Optical Photometry ◽  
Early Results ◽  
Evolutionary Phase ◽  
Red Clump ◽  
Gaia Dr2

ABSTRACT The Blanco Dark Energy Camera (DECam) Bulge survey is a Vera Rubin Observatory (LSST) pathfinder imaging survey, spanning ∼200 deg2 of the Southern Galactic bulge, −2° < b < −13° and −11° < l < +11°. We have employed the CTIO-4 m telescope and the DECam to image a contiguous ∼200 deg2 region of the relatively less reddened Southern Galactic bulge, in SDSS u  + Pan-STARRSgrizy. Optical photometry with its large colour baseline will be used to investigate the age and metallicity distributions of the major structures of the bulge. Included in the survey footprint are 26 globular clusters imaged in all passbands. Over much of the bulge, we have Gaia DR2 matching astrometry to i ∼ 18, deep enough to reach the faint end of the red clump. This paper provides the background, scientific case, and description of the survey. We present an array of new reddening-corrected colour–magnitude diagrams that span the extent of Southern Galactic bulge. We argue that a population of massive stars in the blue loop evolutionary phase, proposed to lie in the bulge, are instead at ∼2 kpc from the Sun and likely red clump giants in the old disc. A bright red clump near (l, b) = (+ 8°, −4°) may be a feature in the foreground disc, or related to the long bar reported in earlier work. We also report the first map of the blue horizontal branch population spanning the Blanco DECam Bulge Survey field of regard, and our data do not confirm the reality of a number of proposed globular clusters in the bulge.

scholarly journals Understanding the Elusive Dwarf Carbon Star

2000 ◽  
Vol 177 ◽  
pp. 27-35 ◽  
Author(s):  
Paul J. Green
Keyword(s):  
Mass Transfer ◽  
Carbon Star ◽  
Carbon Stars ◽  
Wide Range ◽  
Binary Evolution ◽  
Larger Sample

Most stars in our Galaxy with photospheric C/O > 1 (carbon stars) are not giants but dwarfs. The newly-recognized class of dwarf carbon stars joins the growing family of stars with peculiar abundances that are now recognized as products of mass-transfer binary (MTB) evolution. The dozen examples now known span a wide range of evolutionary histories, ages, and abundances. These stars can already provide some much-needed constraints on the formation of AGB C stars in the disk and spheroid populations, and on the parameters characterizing binary evolution there. A larger sample, with some bright members, would hasten our progress.

scholarly journals Dynamical evolution of multiple-population globular clusters

2021 ◽  
Vol 502 (3) ◽  
pp. 4290-4304
Author(s):  
Enrico Vesperini ◽  
Jongsuk Hong ◽  
Mirek Giersz ◽  
Arkadiusz Hypki
Keyword(s):  
Structural Properties ◽  
Globular Clusters ◽  
First Generation ◽  
Radial Profile ◽  
Dynamical Evolution ◽  
Evolutionary Phase ◽  
Dynamical Parameters ◽  
Energy Equipartition

ABSTRACT We have carried out a set of Monte Carlo simulations to study a number of fundamental aspects of the dynamical evolution of multiple stellar populations in globular clusters with different initial masses, fractions of second generation (2G) stars, and structural properties. Our simulations explore and elucidate: (1) the role of early and long-term dynamical processes and stellar escape in the evolution of the fraction of 2G stars and the link between the evolution of the fraction of 2G stars and various dynamical parameters; (2) the link between the fraction of 2G stars inside the cluster and in the population of escaping stars during a cluster’s dynamical evolution; (3) the dynamics of the spatial mixing of the first-generation (1G) and 2G stars and the details of the structural properties of the two populations as they evolve toward mixing; (4) the implications of the initial differences between the spatial distribution of 1G and 2G stars for the evolution of the anisotropy in the velocity distribution and the expected radial profile of the 1G and 2G anisotropy for clusters at different stages of their dynamical history; and (5) the variation of the degree of energy equipartition of the 1G and the 2G populations as a function of the distance from the cluster’s centre and the cluster’s evolutionary phase.

scholarly journals Assessing evidence for adaptive evolution in two hearing-related genes important for high-frequency hearing in echolocating mammals

2021 ◽  
Author(s):  
Hui Wang ◽  
Hanbo Zhao ◽  
Yujia Chu ◽  
Jiang Feng ◽  
Keping Sun
Keyword(s):  
Adaptive Evolution ◽  
Hair Cells ◽  
High Frequency ◽  
Phylogenetic Trees ◽  
Outer Hair Cells ◽  
Functional Domain ◽  
Coding Region ◽  
Selective Pressures ◽  
Wide Range ◽  
Different Parts

Abstract High-frequency hearing is particularly important for echolocating bats and toothed whales. Previously, studies of the hearing-related genes Prestin, KCNQ4, and TMC1 documented that adaptive evolution of high-frequency hearing has taken place in echolocating bats and toothed whales. In this study, we present two additional candidate hearing-related genes, Shh and SK2, that may also have contributed to the evolution of echolocation in mammals. Shh is a member of the vertebrate Hedgehog gene family and is required in the specification of the mammalian cochlea. SK2 is expressed in both inner and outer hair cells, and it plays an important role in the auditory system. The coding region sequences of Shh and SK2 were obtained from a wide range of mammals with and without echolocating ability. The topologies of phylogenetic trees constructed using Shh and SK2 were different; however, multiple molecular evolutionary analyses showed that those two genes experienced different selective pressures in echolocating bats and toothed whales compared to non-echolocating mammals. In addition, several nominally significant positively selected sites were detected in the non-functional domain of the SK2 gene, indicating that different selective pressures were acting on different parts of the SK2 gene. This study has expanded our knowledge of the adaptive evolution of high-frequency hearing in echolocating mammals.

scholarly journals Observations and Models for Red Giants with Unusual Dust

1989 ◽  
Vol 106 ◽  
pp. 367-367
Author(s):  
Ian Griffin ◽  
C.J. Skinner ◽  
B.R. Whitmore
Keyword(s):  
Service Time ◽  
Dust Emission ◽  
Red Giants ◽  
Carbon Stars ◽  
Near Ir ◽  
Medium Resolution ◽  
Silicate Feature ◽  
L Band ◽  
M Stars ◽  
Selection Of

We present near IR (H, K and L band) medium resolution (ƛ/Δƛ ∼ 600) spectra for a selection of 9 red giants which have previously been shown to exhibit anomalous dust emission as characterised by their IRAS LRS spectra. The objects observed (during UKIRT and AAT service time) include Carbon stars whose LRS spectra show the 9.7μm silicate feature and also M stars whose LRS spectra display an 11.3μm feature similar to that usually associated with emission from SiC dust grains.

Dynamical Evolution of Globular Clusters with Mass Spectrum

1991 ◽  
Vol 9 (1) ◽  
pp. 41-44
Author(s):  
Hyung Mok Lee
Keyword(s):  
Mass Spectrum ◽  
Globular Clusters ◽  
Numerical Models ◽  
Relaxation Times ◽  
Dynamical Evolution ◽  
Planck Equation ◽  
Mass Function ◽  
Low Mass Stars ◽  
Wide Range ◽  
Three Body

AbstractWe present a series of numerical models describing the dynamical evolution of globular clusters with a mass spectrum, based on integration of the Fokker-Planck equation. We include three-body binary heating and a steady galactic tidal field. A wide range of initial mass functions is adopted and the evolution of the mass function is examined. The mass function begins to change appreciably during the post-collapse expansion phase due to the selective evaporation of low mass stars through the tidal boundary. One signature of highly evolved clusters is thus the significant flattening of the mass function. The age (in units of the half-mass relaxation time) increases very rapidly beyond about 100 signifying the final stage of cluster disruption. This appears to be consistent with the sharp cut-off of half-mass relaxation times at near 108 years for the Galactic globular clusters.

Review on pharmacological and phytochemical prospects of traditional medicinal plant: Persicaria hydropiper (Smartweed)

2021 ◽  
Vol 21 ◽  
Author(s):  
Abdul Nasir ◽  
Atif Ali Khan Khalil ◽  
Muhammad Zeeshan Bhatti ◽  
Ashfaq Ur Rehman ◽  
Jiayi Li ◽  
...  
Keyword(s):  
Medicinal Plant ◽  
Traditional Medicine ◽  
Northern Hemisphere ◽  
Biological Activities ◽  
Folk Medicine ◽  
Present Review ◽  
Polygonum Hydropiper ◽  
Wide Range ◽  
Pharmacological Data ◽  
Different Parts

: Persicaria hydropiper (L.) Delarbre (family Polygonacea), commonly known as Polygonum hydropiper, is a popular medicinal plant used in traditional medicine. The plant is indigenous to the tropical northern hemisphere and temperate zone including China, Bangladesh, India, and Japan. The plant is used in folk medicine for numerous ailments such as hemorrhoids, antifertility, diarrhea, and dyspepsia. Its medicinal usage in Unani, Ayurveda, Siddha, and other traditional medicine is well-recognized. So far, a wide range of active phytochemicals of this plant has been identified, such as flavonoids, sulphated flavonoids, terpenoids, anthraquinones, steroids, coumarin, simple phenolics, and others. Pharmacological data reported in the literature suggest that various parts of P. hydropiper exhibit antimicrobial, antioxidant, hypoglycemic, antidepressant, cardioprotective, hepatoprotective, anticancer, and antifertility effects. The present review aim is to compile the coherently document research on the phytochemical, pharmacological, and biological activities of P. hydropiper from different parts of the globe.

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