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The spiral pattern rotation speed of the Galaxy and the corotation radius with Gaia DR2
Dias, W. S.; Monteiro, H.; Lépine, J. R. D. +1 more
In this work we revisit the issue of the rotation speed of the spiral arms and the location of the corotation radius of our Galaxy. This research was performed using homogeneous data set of young open clusters (age < 50 Myr) determined from Gaia Data Release 2 (DR2) data. The stellar astrometric membership was determined using proper motions an…
ACRONYM. III. Radial Velocities for 336 Candidate Young Low-mass Stars in the Solar Neighborhood, Including 77 Newly Confirmed Young Moving Group Members
Weinberger, Alycia J.; Kraus, Adam L.; Shkolnik, Evgenya L. +4 more
Young, low-mass stars in the solar neighborhood are vital for completing the mass function for nearby, young coeval groups, establishing a more complete census for evolutionary studies, and providing targets for direct-imaging exoplanet and/or disk studies. We present properties derived from high-resolution optical spectra for 336 candidate young …
Fine-scale Explosive Energy Release at Sites of Prospective Magnetic Flux Cancellation in the Core of the Solar Active Region Observed by Hi-C 2.1, IRIS, and SDO
Tiwari, Sanjiv K.; Golub, Leon; Winebarger, Amy R. +14 more
The second Hi-C flight (Hi-C 2.1) provided unprecedentedly high spatial and temporal resolution (∼250 km, 4.4 s) coronal EUV images of Fe IX/X emission at 172 Å of AR 12712 on 2018 May 29, during 18:56:21-19:01:56 UT. Three morphologically different types (I: dot-like; II: loop-like; III: surge/jet-like) of fine-scale sudden-brightening events (ti…
Using Surface Brightness Fluctuations to Study Nearby Satellite Galaxy Systems: Calibration and Methodology
Greene, Jenny E.; Beaton, Rachael L.; Carlsten, Scott G. +1 more
We explore the use of ground-based surface brightness fluctuation (SBF) measurements to constrain distances to nearby dwarf galaxies. Using archival CFHT Megacam imaging data for a sample of 28 nearby dwarfs, we demonstrate that reliable SBF measurements and distances accurate to 15% are possible even for very low surface brightness (µ …
Disentangling the spatial substructure of Cygnus OB2 from Gaia DR2
Lennon, D. J.; Herrero, A.; Wright, N. J. +2 more
For the first time, we have explored the spatial substructure of the Cygnus OB2 association using parallaxes from the recent second Gaia data release. We find significant line-of-sight substructure within the association, which we quantify using a parametrized model that reproduces the observed parallax distribution. This inference approach is nec…
The Proper-motion Field along the Magellanic Bridge: A New Probe of the LMC-SMC Interaction
van der Marel, Roeland P.; Anderson, J.; Besla, Gurtina +6 more
We present the first detailed kinematic analysis of the proper motions (PMs) of stars in the Magellanic Bridge, from both the Gaia Data Release 2 catalog and from Hubble Space Telescope (HST) Advanced Camera for Surveys data. For the Gaia data, we identify and select two populations of stars in the Bridge region, young main-sequence (MS) and red g…
Fast Outflows Identified in Early Star-forming Galaxies at z = 5-6
Ouchi, Masami; Blaizot, Jérémy; Bouché, Nicolas +3 more
We present velocities of galactic outflows in seven star-forming galaxies at z = 5-6 with stellar masses of M * ∼ 1010.1 {M}⊙ . Although it is challenging to observationally determine the outflow velocities, we overcome this by using ALMA [C II] 158 µm emission lines for systemic velocities and deep Keck spec…
Galaxy structure with strong gravitational lensing: decomposing the internal mass distribution of massive elliptical galaxies
Tam, Sut-Ieng; Nightingale, James W.; Cooper, Andrew P. +4 more
We investigate how strong gravitational lensing can test contemporary models of massive elliptical (ME) galaxy formation, by combining a traditional decomposition of their visible stellar distribution with a lensing analysis of their mass distribution. As a proof of concept, we study a sample of three ME lenses, observing that all are composed of …
The Largest M Dwarf Flares from ASAS-SN
Drout, Maria R.; Kochanek, C. S.; Madore, Barry F. +13 more
The All-sky Automated Survey for Supernovae (ASAS-SN) is the only project in existence to scan the entire sky in optical light approximately every day, reaching a depth of g ∼ 18 mag. Over the course of its first 4 yr of transient alerts (2013-2016), ASAS-SN observed 53 events classified as likely M dwarf flares. We present follow-up photometry an…
The Relationship between Globular Cluster Mass, Metallicity, and Light-element Abundance Variations
Cohen, Roger E.; Ting, Yuan-Sen; Wyse, Rosemary F. G. +7 more
We investigate aluminum abundance variations in the stellar populations of globular clusters using both literature measurements of sodium and aluminum and APOGEE measurements of nitrogen and aluminum abundances. For the latter, we show that the Payne is the most suitable of the five available abundance pipelines for our purposes. Our combined samp…