Search Publications
Identification of emission-line stars in transition phase from pre-main sequence to main sequence
Mathew, Blesson; Kartha, Sreeja S.; Paul, K. T. +3 more
Pre-main-sequence (PMS) stars evolve into main-sequence (MS) phase over a period of time. Interestingly, we found a scarcity of studies in existing literature that examine and attempt to better understand the stars in PMS to MS transition phase. The purpose of this study is to detect such rare stars, which we named as 'transition phase' (TP) candi…
Chemodynamically Characterizing the Jhelum Stellar Stream with APOGEE-2
Cunha, Katia; Smith, Verne V.; Majewski, Steven R. +15 more
We present the kinematic and chemical profiles of red giant stars observed by the Apache Point Observatory Galactic Evolution Experiment (APOGEE)-2 survey in the direction of the Jhelum stellar stream, a Milky Way substructure located in the inner halo of the Milky Way at a distance from the Sun of ≈13 kpc. From the six APOGEE-2 Jhelum pointings, …
Double Peak Structures of Martian Nightside Total Electron Content in Strong Crustal Magnetic Cusp Regions
Futaana, Yoshifumi; Nielsen, Erling; Qin, JunFeng +4 more
With the help of the high spatial resolution total electron content (TEC) data obtained by Mars Advanced Radar for Subsurface and Ionospheric Sounding on board the Mars Express (MEx) during June 2005 to September 2007, the detailed configurations of the Martian nightside ionosphere in crustal magnetic field cusp regions are researched in this pape…
Brightness Fluctuation Spectra of Sun-like Stars. I. The Mid-frequency Continuum
Metcalfe, Travis S.; García, Rafael A.; Mathur, Savita +2 more
We analyze space-based time-series photometry of Sun-like stars, mostly in the Pleiades, but also field stars and the Sun itself. We focus on timescales between roughly 1 hr and 1 day. In the corresponding frequency band these stars display brightness fluctuations with a decreasing power-law continuous spectrum. K2 and Kepler observations show tha…
The GRAVITY young stellar object survey. V. The orbit of the T Tauri binary star WW Cha
Genzel, R.; Sturm, E.; Duchêne, G. +60 more
Context. Close young binary stars are unique laboratories for the direct measurement of pre-main-sequence (PMS) stellar masses and their comparison to evolutionary theoretical models. At the same time, a precise knowledge of their orbital parameters when still in the PMS phase offers an excellent opportunity for understanding the influence of dyna…
Radio-loud and radio-quiet CMEs: solar cycle dependency, influence on cosmic ray intensity, and geo-effectiveness
Joshi, Bhuwan; Chandra, Ramesh; Kharayat, Hema
Coronal mass ejections (CMEs) largely influence the space weather and cause geomagnetic perturbations. Hence, the statistical studies pertaining to the occurrence of CMEs over the solar cycles and their consequence at the near-Earth region are extremely important. For an in-depth understanding, such studies need to be carried out considering vario…
The Fengyun-3E/Joint Total Solar Irradiance Absolute Radiometer: Instrument Design, Characterization, and Calibration
Zhao, Yan; Fang, Wei; Finsterle, Wolfgang +6 more
The Joint Total Solar Irradiance Monitor (JTSIM) is due to fly onboard the Fengyun-3E spacecraft and aims to measure the Total Solar Irradiance (TSI) in orbit. The instruments on the Fengyun-3E/JTSIM include the Digital Absolute Radiometer (DARA) from the Physikalisch Meteorologisches Observatorium, Davos and World Radiation Center (PMOD/WRC) and …
Pre-explosion Properties of Helium Star Donors to Thermonuclear Supernovae
Schwab, Josiah; Götberg, Ylva; Wong, Tin Long Sunny
Helium star-carbon-oxygen white dwarf (CO WD) binaries are potential single-degenerate progenitor systems of thermonuclear supernovae. Revisiting a set of binary evolution calculations using the stellar evolution code MESA, we refine our previous predictions about which systems can lead to a thermonuclear supernova and then characterize the proper…
Multiple Stellar Populations at Less-evolved Stages-II: No Evidence of Significant Helium Spread among NGC 1846 Dwarfs
Li, Chengyuan
The detection of star-to-star chemical variations in star clusters older than 2 Gyr has changed the traditional view of star clusters as canonical examples of "simple stellar populations" into the so-called "multiple stellar populations" (MPs). Although the significance of MPs seems to correlate with cluster total mass, it seems that the presence …
A new search for star forming regions in the southern outer Galaxy
König, C.; Menten, K. M.; Wyrowski, F. +2 more
Context. Star formation in the outer Galaxy is thought to be different from that in the inner Galaxy, as it is subject to different environmental parameters such as metallicity, interstellar radiation field, or mass surface density, which all change with galactocentric radius. Extending our star formation knowledge, from the inner to the outer Gal…