Search Publications
Star formation in the high-extinction Planck cold clump PGCC G120.69+2.66
Djupvik, Anlaug A.; Comerón, Fernando; Yun, João L.
We investigate the star formation occurring in the Planck Galactic cold clump PGCC 120.69+2.66. Near-infrared JHKs images and K-band spectroscopy obtained with NOTCam at the Nordic Optical Telescope complemented with archive data are used to study the stellar content. In addition, millimetre line CO and CS spectra were obtained with the Onsala 20 …
The Million Quasars (Milliquas) Catalogue, v8
Flesch, Eric Wim
Announcing the final release, v8, of the Milliquas (Million Quasars) quasar catalogue which presents all published quasars to 30 June 2023, including quasars from the first releases of the Dark Energy Spectroscopic Instrument (DESI) and the SDSS-DR18 Black Hole Mapper. Its totals are 907,144 type-I QSOs/AGN and 66,026 high-confidence (~99% likelih…
The fastest stars in the Galaxy
Roulston, Benjamin R.; Filippenko, Alexei V.; Strader, Jay +17 more
We report a spectroscopic search for hypervelocity white dwarfs (WDs) that are runaways from Type Ia supernovae (SNe Ia) and related thermonuclear explosions. Candidates are selected from Gaia data with high tangential velocities and blue colors. We find six new runaways, including four stars with radial velocities (RVs) $>1000\,\rm km\,s^{-1}$…
Wide Binaries from GAIA EDR3: preference for GR over MOND?
Sutherland, Will; Pittordis, Charalambos
Several recent studies have shown that velocity differences of very wide binary stars, measured to high precision with GAIA, can potentially provide an interesting test for modified-gravity theories which attempt to emulate dark matter. These systems should be entirely Newtonian according to standard dark-matter theories, while the predictions for…
Wide Binaries as a Modified Gravity test: prospects for detecting triple-system contamination
Manchanda, Dhruv; Sutherland, Will; Pittordis, Charalambos
Recent studies have shown that velocity differences of very wide binary stars, measured to high precision with GAIA, can provide an interesting test for modified-gravity theories which emulate dark matter; in essence, MOND-like theories (with external field effect included) predict that wide binaries (wider than ~ 7 kAU) should orbit ~ 15% faster …
A transiting brown dwarf in a 2 hour orbit
El-Badry, Kareem; Burdge, Kevin B.; Rodriguez, Antonio C. +1 more
We report the discovery of ZTF J2020+5033, a high-mass brown dwarf (BD) transiting a low-mass star with an orbital period of 1.90 hours. Phase-resolved spectroscopy, optical and infrared light curves, and precise astrometry from Gaia allow us to constrain the masses, radii, and temperatures of both components with few-percent precision. We infer a…
The local vertical density distribution of ultracool dwarfs M7 to L2.5 and their luminosity function
Warren, Stephen J.; Ahmed, Saad; Laithwaite, Richard C.
We investigate the form of the local vertical density profile of the stars in the Galactic disk, close to the Galactic plane. We use a homogeneous sample of 34000 ultracool dwarfs M7 to L2.5 that all lie within 350 pc of the plane. We fit a profile of the form sech$^\alpha$, where $\alpha=2$ is the theoretically preferred isothermal profile and $\…
Interplanetary Dust as a Foreground for the LiteBIRD CMB Satellite Mission
Ganga, Ken; Remazeilles, Mathieu; Maris, Michele +1 more
As ever-more sensitive experiments are made in the quest for primordial CMB B Modes, the number of potentially significant astrophysical contaminants becomes larger as well. Thermal emission from interplanetary dust, for example, has been detected by the Planck satellite. While the polarization fraction of this Zodiacal, or interplanetary dust emi…
A Bayesian Approach to the Vertical Structure of the Disk of the Milky Way
Warren, Stephen J.; Dobbie, Phillip S.
This work investigates the vertical profile of the stars in the disk of the Milky Way. The models investigated are of the form $sech^{2/n}(nz/(2H))$ where, setting $\alpha = 2/n$, the three functions of the sequence $\alpha = 0,1,2$ correspond to exponential, $sech$, $sech^2$ functions. We consider symmetric models and asymmetric models, above and…
A Beginner's Guide to Working with Astronomical Data
Pössel, Markus
This elementary review covers the basics of working with astronomical data, notably with images, spectra and higher-level (catalog) data. The basic concepts and tools are presented using both application software (DS9 and TOPCAT) and Python. The level of presentation is suitable for undergraduate students, but should also be accessible to advanced…