Search Publications
Testing Density Wave Theory with Resolved Stellar Populations around Spiral Arms in M81
Dolphin, Andrew E.; Skillman, Evan D.; Williams, Benjamin F. +4 more
Stationary density waves rotating at a constant pattern speed {{{Ω }}}{{P}} would produce age gradients across spiral arms. We test whether such age gradients are present in M81 by deriving the recent star formation histories (SFHs) of 20 regions around one of M81's grand-design spiral arms. For each region, we use resolved stellar popu…
Quiescent Compact Galaxies at Intermediate Redshift in the COSMOS Field. II. The Fundamental Plane of Massive Galaxies
Geller, Margaret J.; Damjanov, Ivana; Chilingarian, Igor +1 more
We examine the relation between surface brightness, velocity dispersion, and size—the fundamental plane (FP)—for quiescent galaxies at intermediate redshifts in the COSMOS field. The COSMOS sample consists of ∼150 massive quiescent galaxies with an average velocity dispersion of σ ∼ 250 km s-1 and redshifts between 0.2 < z < 0.8. …
An Observational Revisit of Band-split Solar Type-II Radio Bursts
Li, Gang; Chen, Yao; Feng, Shiwei +3 more
The band split of solar type II radio bursts, discovered several decades ago, is a fascinating phenomenon, with the type II lanes exhibiting two almost parallel sub-bands with similar morphology. The underlying split mechanism remains elusive. One popular interpretation is that the splitting bands are emitted from the shock upstream and downstream…
Spectroscopic Observations of a Coronal Loop: Basic Physical Plasma Parameters Along the Full Loop Length
Gupta, G. R.; Tripathi, Durgesh; Mason, Helen E.
Coronal loops are the basic structures of the solar transition region and corona. Understanding of the physical mechanisms behind the loop heating, plasma flows, and filling are still considered a major challenge in solar physics. The mechanism(s) should be able to supply mass to the corona from the chromosphere and to heat the plasma over 1 MK wi…
A Theoretical Study on the Vibrational Spectra of Polycyclic Aromatic Hydrocarbon Molecules with Aliphatic Sidegroups
Zhang, Yong; Kwok, Sun; Sadjadi, SeyedAbdolreza
The role of aliphatic side groups in the formation of astronomical unidentified infrared emission (UIE) features is investigated by applying the density functional theory to a series of molecules with mixed aliphatic-aromatic structures. The effects of introducing various aliphatic groups to a fixed polycyclic aromatic hydrocarbon (PAH) core (oval…
The Recent Rejuvenation of the Sun's Large-scale Magnetic Field: A Clue for Understanding Past and Future Sunspot Cycles
Sheeley, N. R., Jr.; Wang, Y. -M.
The quiet nature of sunspot cycle 24 was disrupted during the second half of 2014 when the Sun’s large-scale field underwent a sudden rejuvenation: the solar mean field reached its highest value since 1991, the interplanetary field strength doubled, and galactic cosmic rays showed their strongest 27-day modulation since neutron-monitor observation…
First Detection of Thermal Radiojets in a Sample of Proto-brown Dwarf Candidates
Bouy, Hervé; Palau, Aina; Morata, Oscar +10 more
We observed with the Jansky Very Large Array at 3.6 and 1.3 cm a sample of 11 proto-brown dwarf (BD) candidates in Taurus in a search for thermal radio jets driven by the most embedded BDs. We detected for the first time four thermal radio jets in proto-BD candidates. We compiled data from UKIDSS, 2MASS, Spitzer, WISE, and Herschel to build the sp…
Variations in High Degree Acoustic Mode Frequencies of the Sun during Solar Cycles 23 and 24
Hill, F.; Jain, K.; Tripathy, S. C.
We examine continuous measurements of the high-degree acoustic mode frequencies of the Sun covering the period from 2001 July to 2014 June. These are obtained through the ring-diagram technique applied to the full-disk Doppler observations made by the Global Oscillation Network Group. The frequency shifts in the degree range of 180 ≤slant {\ell } …
The Hubble Wide Field Camera 3 Test of Surfaces in the Outer Solar System: Spectral Variation on Kuiper Belt Objects
Fraser, Wesley C.; Brown, Michael E.; Glass, Florian
Here, we present additional photometry of targets observed as part of the Hubble Wide Field Camera 3 (WFC3) Test of Surfaces in the Outer Solar System. Twelve targets were re-observed with the WFC3 in the optical and NIR wavebands designed to complement those used during the first visit. Additionally, all of the observations originally presented b…
Reconstructing Emission from Pre-reionization Sources with Cosmic Infrared Background Fluctuation Measurements by the JWST
Kashlinsky, A.; Mather, J. C.; Helgason, K. +3 more
We present new methodology to use cosmic infrared background (CIB) fluctuations to probe sources at 10≲ z≲ 30 from a James Webb Space Telescope (JWST)/NIRCam configuration that will isolate known galaxies to 28 AB mag at 0.5-5 µm. At present significant mutually consistent source-subtracted CIB fluctuations have been identified in the Spitze…