Search Publications
Three new Galactic globular cluster candidates: FSR1700, Teutsch67, and CWNU4193
Minniti, D.; Alonso-García, J.; Gómez, M. +3 more
The VISTA Variables in the Via Láctea Extended Survey (VVVX) enables exploration of previously uncharted territories within the inner Milky Way (MW), particularly those obscured by stellar crowding and intense extinction. Our objective is to identify and investigate new star clusters to elucidate their intrinsic characteristics. Specifically, we a…
Discovery of a Proto–White Dwarf with a Massive Unseen Companion
Hermes, J. J.; Zakamska, Nadia L.; El-Badry, Kareem +8 more
We report the discovery of SDSS J022932.28+713002.7, a nascent extremely low-mass (ELM) white dwarf (WD) orbiting a massive (>1 M ⊙ at 2σ confidence) companion with a period of 36 hr. We use a combination of spectroscopy, including data from the ongoing fifth-generation Sloan Digital Sky Survey (SDSS-V), and photometry to measure the…
Using GMM in open cluster membership: An insight
Hasan, P.; Raja, M.; Hasan, S. N. +2 more
The unprecedented precision of Gaia has led to a paradigm shift in membership determination of open clusters where a variety of machine learning (ML) models can be employed. In this paper, we apply the unsupervised Gaussian Mixture Model (GMM) to a sample of thirteen clusters with varying ages (log t ≈ 6.38-9.64) and distances (441-5183 pc) from G…
The Clearing Timescale for Infrared-selected Star Clusters in M83 with HST
Calzetti, Daniela; Johnson, Kelsey E.; Sabbi, Elena +6 more
We present an analysis of Hubble Space Telescope data from Wide Field Camera 3 (WFC3)/Ultraviolet Imaging Spectrometer, WFC3/IR, and the Advanced Camera for Surveys, investigating the young stellar cluster (YSC) population in the face-on spiral galaxy M83. Within the field of view of the IR pointings, we identify 454 sources with compact F814W con…
Relative Yield of Thermal and Nonthermal Emission during Weak Flares Observed by STIX during 2021 September 20–25
Awasthi, Arun Kumar; Mrozek, Tomasz; Kołomański, Sylwester +3 more
The disparate nature of the thermal–nonthermal energy partition during flares, particularly during weak flares, is still an open issue. Following the Neupert effect, quantifying the relative yield of X-ray emission in different energy bands can enable the inferring of the underlying energy release mechanism. During 2021 September 20–25, the Solar …
The Proper Motion of the High Galactic Latitude Pulsar Calvera
Mereghetti, S.; Gotthelf, E. V.; Halpern, J. P. +2 more
Calvera (1RXS J141256.0+792204) is a pulsar of characteristic age 285 kyr at a high Galactic latitude of b = +37°, detected only in soft thermal X-rays. We measure a new and precise proper motion for Calvera using Chandra High Resolution Camera observations obtained 10 yr apart. We also derive a new phase-connected ephemeris using 6 yr of NICER da…
9 New Variable Stars in Exoplanetary Transit Fields Observed at the Caucasus Mountain Observatory
Tarasenkov, A.; Zubareva, A. M.; Maslennikova, N. +1 more
Why Observations at Mid-infrared Wavelengths Partially Mitigate M Dwarf Star Host Stellar Activity Contamination in Exoplanet Transmission Spectroscopy
Seager, Sara; Shapiro, Alexander I.
Exoplanet atmosphere transmission spectroscopy for planets orbiting M dwarf stars faces significant challenges due to contamination from stellar magnetic features, i.e., spots and faculae. These features make the stellar surface inhomogeneous and introduce wavelength-dependent signals in the transmission spectrum that complicate its analysis. We i…
Airglow and Aurora in the Martian Atmosphere: Contributions by the Mars Express and ExoMars TGO Missions
Montmessin, Franck; Fedorova, Anna; Gérard, Jean-Claude +6 more
The study of atmospheric emissions from orbit to probe the middle and upper atmosphere of Mars, which started with the Mariner missions, is living a golden era thanks to the European Space Agency (ESA) Mars Express mission and other subsequent missions built upon its success, including the ESA ExoMars Trace Gas Orbiter (TGO) mission. Here we summa…
Origins of Very Low Helium Abundance Streams Detected in the Solar Wind Plasma
Yashiro, Seiji; Gopalswamy, N.; Srivastava, Nandita +4 more
The abundance of helium (A He) in the solar wind exhibits variations typically in the range from 2% to 5% with respect to solar cycle activity and solar wind velocity. However, there are instances where the observed A He is exceptionally low (<1%). These low-A He occurrences are detected both near the Sun and at…