Search Publications
Understanding the physical properties of young M dwarfs: NIR spectroscopic studies
Mondal, Soumen; Das, Ramkrishna; Khata, Dhrimadri +2 more
We present here medium resolution (λ/Δλ ∼ 1200) H- and K-band spectra of M-type dwarf stars covering the wavelength ranges 1.50-1.80 µm and 1.95-2.45 µm. The sample includes 53 dwarf stars (M0V-M7V) from new observations using the TIFR Near-Infrared Spectrometer and Imager instrument on the 2-m Himalayan Chandra Telescope. Using interf…
RW Aur B: a modest UX Ori-type companion of the famous primary
Petrov, P.; Takami, M.; Safonov, B. +3 more
The secondary of the famous young binary RW Aur is much less studied than the primary. To rectify this shortcoming, we present here the results of UBVRIJHK photometric, VRI polarimetric and optical spectral observations of RW Aur B. The star demonstrates chaotic brightness variations in the optical band, with irregular, short (∼1-d) dimmings with …
The M dwarf problem: Fe and Ti abundances in a volume-limited sample of M dwarf stars
Wallerstein, George; Woolf, Vincent M.
We report iron and titanium abundance measurements from high-resolution spectra in a volume-limited sample of 106 M0 and M0.5 dwarf stars. The sample includes stars north of the celestial equator and closer than 29 parsecs. The results imply that there is an M dwarf problem similar to the previously known G dwarf problem, in that the fraction of l…
A multiwavelength search for black widow and redback counterparts of candidate γ-ray millisecond pulsars
Tiengo, A.; Belfiore, A.; Marelli, M. +6 more
The wealth of detections of millisecond pulsars (MSPs) in γ-rays by Fermi has spurred searches for these objects among the several unidentified γ-ray sources. Interesting targets are a sub-class of binary MSPs, dubbed 'black widows' (BWs) and 'redbacks' (RBs), which are in orbit with low-mass non-degenerate companions fully or partially ablated by…
Keck Cosmic Web Imager (KCWI) spectra of globular clusters and ultracompact dwarfs in the halo of M87
Forbes, Duncan A.; Romanowsky, Aaron J.; Brodie, Jean P. +2 more
Using the Keck Cosmic Web Imager, we obtain spectra of several globular clusters (GCs), ultracompact dwarfs (UCDs), and the inner halo starlight of M87, at a similar projected galactocentric radius of ~5 kpc. This enables us, for the first time, to apply the same stellar population analysis to the GCs, UCDs, and starlight consistently to derive ag…
Infrared properties of planetary nebulae with [WR] and wels central stars
Parthasarathy, M.; Muthumariappan, C.
We report the infrared (IR) properties of planetary nebulae (PNe) with Wolf-Rayet (WR) type and wels central stars known to date and compare them with the IR properties of a sample of PNe with H-rich central stars. We use near-, mid-, and far-IR photometric data from archives to derive the IR properties of PNe. We have constructed IR colour-colour…
Hot gaseous atmospheres of rotating galaxies observed with XMM-Newton
Gaspari, M.; Nulsen, P. E. J.; Donahue, M. +6 more
X-ray emitting atmospheres of non-rotating early-type galaxies and their connection to central active galactic nuclei have been thoroughly studied over the years. However, in systems with significant angular momentum, processes of heating and cooling are likely to proceed differently. We present an analysis of the hot atmospheres of six lenticular…
Resolved observations at 31 GHz of spinning dust emissivity variations in ρ Oph
Bond, J. Richard; Hensley, Brandon S.; Casassus, Simon +9 more
The ρ Oph molecular cloud is one of the best examples of spinning dust emission, first detected by the cosmic background imager (CBI). Here, we present 4.5 arcmin observations with CBI 2 that confirm 31 GHz emission from ρ Oph W, the PDR exposed to B-type star HD 147889, and highlight the absence of signal from S1, the brightest IR nebula in the c…
Extreme ultraviolet quasar colours from GALEX observations of the SDSS DR14Q catalogue
Wu, Jian; Vanden Berk, Daniel E.; Wesolowski, Sarah C. +4 more
The rest-frame far to extreme ultraviolet (UV) colour-redshift relationship has been constructed from data on over $480\, 000$ quasars carefully cross-matched between SDSS Data Release 14 and the final GALEX photometric catalogue. UV matching and detection probabilities are given for all the quasars, including dependencies on separation, optical b…
Gas and star formation from HD and dust emission in a strongly lensed galaxy
Maiolino, R.; Caselli, P.; Carniani, S. +1 more
The molecular gas content of high-redshift galaxies is a highly sought-after property. However, H2 is not directly observable in most environments, so its mass is probed through other emission lines (e.g. CO, [C I], [C II]), or through a gas-to-dust ratio. Each of these methods depends on several assumptions, and are best used in parall…