Search Publications
Far ultra-violet insights into NGC 1399's globular cluster population
Kundu, Arunav; Dage, Kristen C.; Zepf, Stephen E. +2 more
We investigate archival Hubble Space Telescope ACS/SBC F140LP observations of NGC 1399 to search for evidence of multiple stellar populations in extragalactic globular clusters. Enhanced far-ultraviolet (FUV) populations are thought to be indicators of He-enhanced second generation populations in globular clusters, specifically extreme/blue horizo…
Analysis of metallicities of open clusters in the Galactic disc
Li, Zhongmu; Deng, Yangyang
The metallicities of open clusters (OCs) are probes for many Galactic disc properties, such as age-metallicity relation and abundance gradient evolution. In recent years, a large number of newly found OCs or OC candidates have been reported. However, the metallicity values of OCs in the Galactic disc in different works vary from each other. In par…
Probabilistic classification of infrared-selected targets for SPHEREx mission: in search of young stellar objects
Kang, Miju; Ashby, Matthew L. N.; Hora, Joseph L. +3 more
We apply machine learning algorithms to classify infrared (IR)-selected targets for NASA's upcoming Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer (SPHEREx) mission. In particular, we are interested in classifying young stellar objects (YSOs), which are essential for understanding the star formation pro…
Limiting the accretion disc light in two mass transferring hot subdwarf binaries
Mereghetti, Sandro; Piirola, Vilppu; Kupfer, Thomas +6 more
We report the results from follow-up observations of two Roche-lobe filling hot subdwarf binaries with white dwarf companions predicted to have accretion discs. ZTF J213056.71+442046.5 (ZTF J2130) with a 39-min period and ZTF J205515.98+465106.5 (ZTF J2055) with a 56-min period were both discovered as subdwarf binaries with light curves that could…
Time-series photometry and multiwavelength characterization of the young stellar cluster Mon R2
Cieza, Lucas A.; Gamen, Roberto; Orcajo, Santiago
Using the Las Cumbres Observatory Global Telescope Network (LCOGT), we have obtained multi-epoch photometry of the young cluster Mon R2. We have monitored over 6000 sources with i-band between 13 and 23 mag within a 26 × 26 arcmin2 field of view. For each star, we collected ~1500 photometric points covering a temporal window of 23 d. Ba…
Accretion in the binary system GG Carinae and implications for B[e] supergiants
Kashi, Amit
We simulate the hydrodynamics of the wind flow in the B[e] supergiant binary system GG Carinae and obtain the mass accretion rate on to the secondary and the observed light curve. We find an inhomogeneous Bondi-Hoyle-Lyttleton accretion into a curved accretion tail, and confirm that the accretion rate is modulated along the orbit, with a maximum c…
Relation between photometric and parameter errors of star clusters
Li, Zhongmu; Liu, Xuejie
Many observations supply only photometry data with large uncertainties. The study of star clusters based on such data is important for astrophysical studies, although photometric uncertainty affects the accuracy of results. In order to estimate the parameter uncertainties that are caused by photometric errors, this work quantifies the influence of…
A helium nova in the Large Magellanic Cloud - the faint supersoft X-ray source [HP99]159
Kato, Mariko; Hachisu, Izumi; Saio, Hideyuki
We propose a helium nova model for the Large Magellanic Cloud (LMC) supersoft X-ray source (SSS) [HP99]159. This object has long been detected as a faint and persistent SSS for about 30 yr, and recently been interpreted to be a source of steady helium-shell burning, because no hydrogen lines are observed. We find that the object can also be interp…
Globular Cluster UVIT Legacy Survey (GlobULeS) - II. Evolutionary status of hot stars in M3 and M13
Pradhan, Ananta C.; Sahu, Snehalata; Subramaniam, Annapurni +4 more
We present a far-ultraviolet (FUV) study of hot stellar populations in the second parameter pair globular clusters (GCs) M3 and M13, as a part of the GC UVIT Legacy Survey programme (GlobULeS). We use observations made with F148W and F169M filters of the Ultraviolet Imaging Telescope (UVIT) onboard AstroSat along with ground-based data (UBVRI filt…
The variable stars in the field of NGC 6139: a critical approach to their reddening and membership
Arellano Ferro, A.; Luna, A.; Yepez, M. A. +1 more
We present a CCD VI time-series analysis of the globular cluster NGC 6139 and its variable star population. Using the astrometric data available in Gaia-DR3, we performed a membership analysis that enabled the construction of a clean colour-magnitude diagram (CMD). Variable stars in the field of the cluster reported by Gaia-DR3 and newly discovere…