Yellow Star Research Articles

Characterization of Blue and Yellow Straggler Stars of Berkeley 39

We characterize blue straggler stars (BSSs) and yellow straggler stars (YSSs) of the open cluster (OC) Berkeley 39 using multiwavelength observations including the Swift/Ultraviolet and Optical Telescope (UVOT). Our analysis also makes use of ultraviolet (UV) data from Galaxy Evolution Explorer, optical data from Gaia DR3 and Panoramic Survey Telescope and Rapid Response System, and infrared data from Two Micron All Sky Survey, Spitzer/IRAC, and Wide-field Infrared Survey Explorer. Berkeley 39 is a ∼6 Gyr old Galactic OC located at a distance of ∼4200 pc. We identify 729 sources as cluster members utilizing a machine-learning algorithm, ML-MOC, on Gaia DR3 data. Of these, 17 sources are classified as BSS candidates and four as YSS candidates. We construct multiwavelength spectral energy distributions (SEDs) of 16 BSS and two YSS candidates, within the Swift/UVOT field, to analyze their properties. Out of these, eight BSS candidates and both the YSS candidates are successfully fitted with single-component SEDs. Five BSS candidates show marginal excess in the near-UV (NUV; fractional residual <0.3 in all but one UVOT filter), whereas three BSS candidates show moderate to significant excess in the NUV (fractional residual >0.3 in at least two UVOT filters). We present the properties of the BSS and YSS candidates, estimated based on the SED fits.

WIYN Open Cluster Study. XC. Radial-velocity Measurements and Spectroscopic Binary Orbits in the Open Cluster NGC 2506

NGC 2506 is a rich, intermediate-age (2.0 Gyr), metal-poor ([Fe/H] ∼ −0.2) open cluster. This work presents the results of 12,157 spectroscopic radial-velocity measurements of 2442 stars in the NGC 2506 field obtained over 41 yr, made as part of the WIYN Open Cluster Study. Radial-velocity measurements are complete for the population of proper-motion member stars brighter than a Gaia G magnitude of 15.5, in which 320 proper-motion and radial-velocity cluster members were identified. Within the observation limit of G < 16.5, 469 proper-motion and radial-velocity members were identified. This work reports on the characteristics of NGC 2506, including projected spatial distribution, radial-velocity dispersion, and virial mass. This work also presents orbital solutions for 49 binary members with periods between 1 and 7580 days. NGC 2506 has an incompleteness-corrected binary frequency for binaries with periods less than 104 days of 35% ± 5%. This work also discusses in detail the 14 blue stragglers stars of NGC 2506—finding at least 64% ± 21% to be in binaries, five yellow straggler stars, and several other stars of note.

CHARA Near-infrared Imaging of the Yellow Hypergiant Star ρ Cassiopeiae: Convection Cells and Circumstellar Envelope

Massive evolved stars such as red supergiants and hypergiants are potential progenitors of Type II supernovae, and they are known for ejecting substantial amounts of matter, up to half their initial mass, during their final evolutionary phases. The rate and mechanism of this mass loss play a crucial role in determining their ultimate fate and the likelihood of their progression to supernovae. However, the exact mechanisms driving this mass ejection have long been a subject of research. Recent observations, such as the Great Dimming of Betelgeuse, have suggested that the activity of large convective cells, combined with pulsation, could be a plausible explanation for such mass-loss events. In this context, we conducted interferometric observations of the famous yellow hypergiant, ρ Cassiopeiae using the CHARA Array in H- and K-band wavelengths. ρ Cas is well known for its recurrent eruptions, characterized by periods of visual dimming (∼1.5–2 mag) followed by recovery. From our observations, we derived the diameter of the limb-darkened disk and found that this star has a radius of 1.04 ± 0.01 mas, or 564–700 R ⊙. We performed image reconstructions with three different image reconstruction software packages, and they unveiled the presence of giant hot and cold spots on the stellar surface. We interpret these prominent hot spots as giant convection cells, suggesting a possible connection to mass ejections from the star’s envelope. Furthermore, we detected spectral CO emission lines in the K band (λ = 2.31–2.38 μm), and the image reconstructions in these spectral lines revealed an extended circumstellar envelope with a radius of 1.45 ± 0.10 mas.

UOCS XIV: Study of the Open Cluster NGC 2627 Using UVIT/AstroSat

We study the intermediate-age open cluster NGC 2627, located at a distance of ∼2 kpc, using UVIT/AstroSat and other archival data. Using a machine learning-based algorithm, ML-MOC, on the Gaia DR3 data, we identify 422 cluster members, including four blue straggler stars (BSSs), one yellow straggler star (YSS), one blue lurker (BL), one red clump (RC) star, and two binary candidates with detection in both UVIT/F148W and UVIT/F169M filters. We characterise them using multiwavelength spectral energy distributions (SEDs). Out of the above nine sources, one BSS, the BL, and one binary candidate have a source nearby; hence, we did not fit their SEDs. Of the remaining six sources, we successfully fit two with single-component SEDs and four with binary-component SEDs. The binary-component SED-based parameters indicate that the hot companions of BSSs, the YSS, the RC star, and the binary candidate are extremely low-mass white dwarfs, confirming that at least four out of nine stars (44%) are formed via the mass transfer channel. We fit King’s profile function to the high-probability (p > 0.8) cluster members and estimate the cluster core radius (r C ) to be 3.84′ and the tidal radius (r t ) to be 36.85′. We find that the equal-mass binaries are most concentrated towards the cluster center, followed by the single massive stars, and single low-mass stars. The BSS population of the cluster is also found to be located within a radius r ∼ 10 × r C from the cluster center, suggesting the dynamical evolution of the cluster.

Yellow hypergiant V509 Cas: Stable in the ‘yellow void’

Context. The yellow hypergiant star V509 Cas is currently undergoing an extreme phase of evolution. Having experienced eruptive mass-loss outbursts in the 20th century, the star’s effective temperature reached record high values in the early 2000s. However, since then, the star’s behaviour has displayed an unprecedented level of stability. In spite of that, the star could be traversing through the ‘yellow void’ instability region. Aims. To describe the current evolutionary state of V509 Cas, we analysed its variability using photometric and spectroscopic data collected over recent years. By comparing our findings with historical records, we aim to determine whether the star’s surface shows signs of stabilisation. Additionally, we investigate the variability of emission components in the wings of certain spectral lines to highlight the contribution of the circumstellar gaseous disc to this phenomenon. Methods. Our spectroscopic monitoring observations were carried out at Tartu Observatory over the course of seven years, supplemented by echelle spectra obtained at the Nordic Optical Telescope, as well as publicly available photometric data from Gaia, AAVSO, and AAVSO’s Bright Star Monitor programme. We estimated the variability of effective temperature and radial velocity from the spectral time series and correlated it with the brightness variability of V509 Cas. Results. The results indicate that the star’s average brightness level has remained stable throughout the observed period, with an amplitude of variability ∼0.1 mag. While the amplitude of short-term temperature fluctuations has decreased compared to the early 2000s, the variability of the radial velocity remains similar to historical values from the early 20th century. Moreover, we show how the variable radial velocity affects the emission components in some absorption lines (e.g. Sc II) and how that follows the hypothesis of a disc surrounding the star.

Lithium-rich Cepheid V470 Cas

In this Letter, we report the discovery of a new lithium-rich yellow supergiant star -- the Cepheid V470 Cas -- that has a high lithium abundance, $ A(Li)$ = 3.29. This is highly unusual for supergiant stars. V470 Cas is joining a very select group of lithium-rich Cepheids, with only nine members known to date in our Galaxy. For the analysis of our high-resolution echelle spectrum obtained at the Canada-France-Hawaii Telescope, methods based on both local thermodynamic equilibrium (LTE) and non-local thermodynamic equilibrium (NLTE) assumptions were applied. In particular, the lithium abundance was derived by analysing the equivalent width of the 6707 line. Most lithium-rich Cepheids are located near the blue edge of the instability strip near the bottom of the Hertzsprung--Russell diagram. Their main sequence progenitors are distributed over a mass range of three to five solar masses. Of the nine lithium-rich Cepheids known, six are double-mode pulsators, including our programme Cepheid. It is very likely that the stars of this small group are entering the instability strip for the first time and have not yet passed the red giant phase. Therefore, they have not experienced the large-scale mixing event that could destroy lithium in their convective zones.

Elaine Goodale Eastman’s Yellow Star as Counter-Narrative for American Indian History-Telling

AbstractIn 1911, Elaine Goodale Eastman, longtime editor of writing by her husband, Indigenous writer Charles Eastman (Ohiyesa), published Yellow Star, a narrative for white family audiences. Both the Eastmans’ already-troubled marriage and their parenting of mixed-race children illuminate the text, as does their history of linked authorial experiences. Anticipating twenty-first-century battles over competing historical narratives about Indigenous peoples in school curricula and public discourse, Yellow Star’s depiction of history-in-the-making underscores intersections between the domestic and the public, as well as between communal lived experience and larger social issues. The text simultaneously claims a potential role for young people’s literature in the cultural construction of historical understanding. Eastman’s main character, Stella/Yellow Star, arrives in a fictional New England village as an orphan of the Wounded Knee Massacre. Determined to continue valuing her Indigenous community, Stella models both a particular brand of assimilation and resistance to its would-be totalizing power. Before returning west to teach children of her tribe, she also articulates an alternative historical voice. Yellow Star draws on Eastman’s background as a white woman involved in assimilationist education. Progressive in her commitment to on-reservation learning rather than boarding schools, Goodale Eastman was nonetheless implicated in white culture’s racial hierarchies.

Teaching Charles Alexander Eastman’s “The North American Indian” in Dialogue with Elaine Goodale Eastman’s Yellow Star

AbstractCharles Eastman’s “The North American Indian” address for the 1911 Universal Races Congress (URC) in London provides multiple pathways for teaching in a comparative context. One productive approach involves setting the lecture in dialogue with Elaine Goodale Eastman’s Yellow Star, published in the same year. Another entails asking students to situate Charles Eastman’s talk in the context of the URC as a vital milestone in global thought leaders’ engagement with questions about race. This approach could include juxtaposing Eastman’s lecture with one by W. E. B. Du Bois delivered at the same convention. Pedagogy for Eastman’s speech can also locate this text in the context of his larger oeuvre, including more assertively anticolonial discourse in later writings for Indigenous readers.

Blue Straggler Stars of NGC 7789 and NGC 2506 Using AstroSat/UVIT

Blue straggler stars are intriguing objects that seem to defy the standard theory of single-star evolution. They manage to elongate their main-sequence lifetimes by acquiring mass either in a direct stellar collision or through mass transfer in a binary or in mergers. We study the candidate blue straggler stars in two intermediate-age open clusters NGC 7789 and NGC 2506 using the far-UV and near-UV observations from the UV imaging telescope of AstroSat in combination with other multi-wavelength data. Around 45% of blue straggler star candidates show an excess in the UV wavelengths and are fitted with two-component spectral energy distributions. We detect most of these blue straggler stars to contain a low-mass or extremely low-mass white dwarf as a hot companion, whereas some yellow straggler stars and red clump stars with white dwarfs of normal mass or high mass as a companion. Based on our analysis, we infer that around 36% of blue straggler stars have likely formed via mass transfer by the Case-A/Case-B mechanism in these two clusters.

Distance to Leo A Based on a Post-asymptotic-giant-branch Star

A yellow post-asymptotic-giant-branch (PAGB) star was recently identified in the dwarf galaxy Leo A. Using this yellow PAGB star, I derived a distance of 794.3 ± 10.0 kpc to Leo A, illustrating the yellow PAGB star can be used as a distance indicator.

Rēzekne Jewish Cemetery as a Representative Substructure of the “Other” in the Culture of Latgale

The aim of this study is to analyze the verbal and non-verbal signs of the Rēzekne Jewish cemetery with the cultural semiotic approach and to find out the hybridization features of the Jewish semiosphere in Latgale. The article describes the Rēzekne Jewish cemetery as a representative substructure of the “other” in the culture of Latgale with special traditions of language and ritual graphics, valuable genealogical material and historical evidence about the fate of local Jews and with a special tomb cult, determined by the ethnically diverse environment.&#x0D; Jews in Latgale have always nurtured and preserved their cultural otherness; this is also characteristic of their traditions of arranging cemeteries. Depending on the cultural and social trends of the relevant era, it is possible to trace changes in the formation of grave inscriptions, graphics and forms. Interrelations with the traditions of the local majority, the Latgalians, show the hybridization of the culture of Jewish cemeteries. In the 20th century, Yiddish is gradually disappearing from grave inscriptions, that is caused by decreasing of the number of its speakers. During the Soviet occupation, the role of the sacred language – Hebrew in grave inscriptions decreased, while the proportion of Russian in the narrative of the inscriptions increased. During the last decade of the 20th century, grave inscriptions are predominant in Russian, which confirms the decline in the number of Hebrew speakers. The symbolic meaning of tomb cult graphics in the second half of the 20th century levels off, and local Jews take over Latgalian traditions of the design of tombstones. The graphic shows the transmission of information to the receivers of the “other” culture, for example, the yellow Star of David is represented instead of the menorah, since the yellow six-pointed star is more recognizable to the local population as a testimony of the Holocaust. A menorah may not cause an association with a Jew, because candles and candlesticks are usual graphic elements of Latgalian tombs. Such a trend in the choice of symbols indicates a unique cultural dialogue and its implementation tools, which are oriented towards the self-presentation of a separate ethnic group, using recognizable stereotypical signs instead of specific cult symbols, the language of local residents instead of their sacred language. They want to be understood and understandable for themselves because the number of people who know the authentic meaning of Hebrew and sacred cult signs in Latgale and Rēzekne is quite small. In any case, communication or cultural dialogue still exists, at least the tomb culture is still capable of transmitting its basic values in the form of stereotypical, well-known signs. In this way, the “other” tends to be noticed and understood.

UOCS-XII. A study of open cluster NGC 6940 using UVIT/AstroSat cluster properties and exotic populations

ABSTRACT We study an open cluster NGC 6940 using AstroSat/UVIT (Ultraviolet Imaging Telescope) data and other archival data. This is an intermediate age cluster (∼1 Gyr), located at about 770 pc distance, harbouring several exotic populations apart from normal single and binary stars. We identify members of this cluster using a machine learning algorithm, ML-MOC and identify 492 members, including one blue straggler star (BSS), two yellow straggler stars (YSS), 11 blue lurker (BL) candidates, and two red clump (RC) stars. The cluster shows the effect of mass segregation, with massive stars segregated the most into the cluster, followed by the equal-mass binary members and the single low-mass stars. We report the presence of an extended main-sequence turn-off (eMSTO) feature in this cluster and suggest that the age spread may be a contributing factor behind it. However, the effect of stellar rotation, and the dust absorption needs to be examined more comprehensively with a larger fraction of MSTO stars. All the sixteen sources mentioned above have a counterpart in the UVIT/F169M filter. In order to characterize them, we construct multi-wavelength spectral energy distributions (SEDs) of 14 of these objects having no nearby sources within 3 arcsec. The BSS is successfully fitted with a single-component SED. We find that three BLs, two YSS, and one RC star have UV excess greater than 50 per cent and successfully fit two-component SEDs having hot companions. The parameters derived from the SEDs imply that the hot companions of BLs and the RC star are low-mass and normal-mass white dwarfs, whereas the hot companions of YSS are likely to be subdwarf B stars. We suggest that at least 6 out of 14 stars (∼42 per cent) are formed via mass transfer and/or merger pathways.

A study of chemical abundances, rotational velocities, and orbital elements in single-lined spectroscopic binary stars in open clusters

ABSTRACT Binary interactions play a significant role in stellar evolution. In this study, we present a comprehensive analysis of 17 single-lined spectroscopic binary stars and identify two more as ‘yellow stragglers’, in the context of 15 young open clusters with ages younger than 1.0 Gyr. High-resolution spectroscopy ($R\, \approx \, 48000$) was employed to determine atmospheric parameters and chemical abundances of various elements including Li, C (C2), N (12CN), O, Na, Mg, Al, Ca, Si, Ti, Ni, Cr, Y, Zr, La, Ce, Nd, and Eu, and compared them with the abundances of stars reported in the literature. The projected rotational velocities ($v\, \sin \, \mathrm{ i}$) of 17 stars were determined via the spectral synthesis method. For two stars, we analyse the phenomenon of yellow stragglers based on their spectra and colour–magnitude diagram. Our $v\, \sin \, \mathrm{ i}$ results exhibit excellent agreement with previous studies in the literature for four stars previously analysed. Furthermore, we found a similar set of chemical abundances between thin disc stars and the studied spectroscopic binaries, except for s-process elements, such as La, Ce, and Nd. Also, we confirm that yellow straggler stars are members of binary systems, specifically giant G/K-type stars paired with dwarf A-type stars. Finally, we investigated the relationships between chemical abundances, orbital parameters (obtained from the literature), and $v\, \sin \, \mathrm{ i}$, which can provide insights into the observed anomalies in 7Li abundance in two stars such as NGC 6694-14 and NGC 6709-303. Our findings suggest that the anomalous rotation and lithium enrichment observed in these stars are likely results of interactions within binary companions.

Yellow Star, Red Star: Response to Critiques

There is no greater honor for an author than to respond to such generous and thoughtful engagement with one’s work such as the two commentaries by Mila Dragojević and Tamara Trošt. These commentaries are that much more appreciated as both Dragojević and Trošt have contributed tremendous scholarship on memory politics and historical narratives in the Western Balkans and in many ways Yellow Star, Red Star builds on their own work.

VISUAL SEMIOTICS IN THE STUDY OF ART PHENOMENA: SYMBOL AND SYMPTOM

The study aims to use the approach of visual semiotics to analyse the ritual graphic signs of the Rezekne Jewish cemetery as a segment of the city in terms of "signifier" and "signified", or “expression” and “content”. The Star of David, as the dominant sign of the ritual graphics, is gradually losing the status of a sacred symbol and in a series of tombstones confirms the structure of a symptom. The paper is devoted not only to clarifying the cultural and social causes of such changes but also to the study of the mechanism of mutual transitions between symbols and symptoms, the differences in the coding of these types of signs, which has not been done in visual semiotics so far.Theoreticians have hitherto not paid due attention to the study of signs of graves as a segment of the urban environment. Moreover, the theory of visual semiotics also lacks a description of the specificity of signs in ritual graphics. Ritual graphics is an important indicator of the regularity of cultural processes in an ethnically diverse environment. When surveying the Jewish cemeteries of the Latgale region, the difference in the choice of visual graphics in the city and the countryside is obvious. In rural cemeteries that are still in use, the content and structure of verbal messages, as well as decorative graphics are traditional, therefore predictable. In city cemeteries, there is a change in graphics, deviations from tradition, its modification and obvious violations of tradition. Along with the verbal report about the deceased, the ritual graphic, on the one hand, complements it as an integral part, on the other hand, lives an independent life, because the first, and the only sign that the observer notices is the visual or non-verbal sign. In terms of information, the visual sign is noticeably more capacious, as it is older than the verbal and requires much less time for perception. The focus of the study is the divergence between the meanings of the sacred hexagram and the secular yellow star or “badge”, the causal relationships of their use and perception from the point of view of visual semiotics and cultural philosophy - phenomena of symbolization and desymbolization.

Combating the Double Erasure: Can a Jew (Kalimi) be an Iranian in the Islamic Republic?

AbstractSince the 1979 revolution, Iranian Jews have faced two powerful and inherently contradictory calls to compromise their voice and identity. From one side, Israel has consistently held the opinion that as an at-risk community they should be evacuated and resettled. On the other, Iran's revolutionary regime has made “Islamic” a centerpiece of Iranian identity, placing Jewish identity directly at odds with what it means to be an Iranian. For decades, foreign opposition groups have spread baseless and unsubstantiated claims suggesting that Iranian Jews are to be placed in concentration camps or forced to wear yellow stars. At the same time, Iran's top politicians repeatedly peddle anti-Semitic innuendo and promote Holocaust denial conspiracies. Yet such narratives miss the central fact rarely acknowledged in Israel or Western academic and public spheres: Iranian Jews have continued to maintain ownership of their story and narrative as both Iranian and Jewish. This article seeks to analyze the navigation of Iranian Jews between their struggle as a religious minority in the Islamic Republic and maintenance of their autonomous voice as represented outside Iran.

Pengaruh Motivasi Intrinsik, Komunikasi Persuasif dan Stres Kerja terhadap Komitmen Afektif Studi pada Hotel Yellow Star Ambarrukmo

This study aims to determine (1) the effect of intrinsic motivation on affective commitment, (2) persuasive communication on affective commitment, (3) work stress on affective commitment, and (4) the effect of intrinsic motivation, persuasive communication and work stress together. on Affective Commitment. The research used is the type of quantitative research method. This research was conducted at the Yellow Star Ambarrukmo Hotel. The number of employees is 60 using nonprobability sampling technique. The data collection method uses a questionnaire and is free. This research uses data quality test, classical assumption test including (normality test, heteroscedasticity test and multicollinearity test) multiple linear regression test and hypothesis test. The results of this study indicate that the Intrinsic Motivation Variable has a positive effect on Affective Commitment. Persuasive Communication Variable has a positive effect on Affective Commitment. Job Stress Variable has a negative effect on Affective Commitment. The Variables of Intrinsic Motivation, Persuasive Communication and Job Stress jointly or simultaneously influence the Affective Commitment Variable.

UOCS-IX. AstroSat/UVIT Study of the Open Cluster NGC 2818: Blue Stragglers, Yellow Stragglers, Planetary Nebula, and their Membership

We present the first far-UV (FUV) imaging results of the intermediate-age Galactic open cluster NGC 2818 that has a planetary nebula (PN) within the field using images taken from the Ultra Violet Imaging Telescope (UVIT) aboard AstroSat. We identify cluster members by combining UVIT-detected sources with Gaia EDR3 data. We detect four bright and hot blue straggler stars (BSSs) and two yellow straggler stars (YSSs) based on their location in optical and FUV–optical color–magnitude diagrams. Based on the parameters estimated using spectral energy distributions, we infer that BSSs are either collisional products or might have undetectable white dwarf (WD) companions. Our photometric analysis of YSSs confirms their binarity, consistent with the spectroscopic results. We find YSSs to be formed through a mass-transfer scenario and the hot components are likely to be A-type subdwarfs. A comparison of the radial velocity, Gaia EDR3 proper motion of the PN with the cluster, and reddening toward the PN and the cluster does not rule out the membership of the PN. Comparing the central star’s position with theoretical post‐AGB (pAGB) models suggest that it has already entered the WD cooling phase, and its mass is deduced to be ∼0.66 M ⊙. The corresponding progenitor mass turns out to be ∼2.1 M ⊙, comparable to the turn-off mass of the cluster, implying that the progenitor could have formed in the cluster. We suggest that the NGC 2818 might be one of the few known clusters to host a PN, providing a unique opportunity to test stellar evolution models.

Dermoscopic Findings of Clonal Seborrheic Keratosis and Pigmented Basal Cell Carcinoma in the Skin of Color Patients - A Comparison.

Dermoscopic Findings of Clonal Seborrheic Keratosis and Pigmented Basal Cell Carcinoma in the Skin of Color Patients - A Comparison.

Dermoscopy of Cylindroma in Fitzpatrick Type IV Skin: A Case Report and Review of Literature.

Dermoscopy of Cylindroma in Fitzpatrick Type IV Skin: A Case Report and Review of Literature.