Search Publications
The Characterization of the Dust Content in the Ring Around Sz 91: Indications of Planetesimal Formation?
Palau, Aina; Carrasco-González, Carlos; Olofsson, Johan +6 more
One of the most important questions in the field of planet formation is how millimeter- and centimeter-sized dust particles overcome radial drift and fragmentation barriers to form kilometer-sized planetesimals. ALMA observations of protoplanetary disks, in particular transition disks or disks with clear signs of substructures, can provide new con…
A Preliminary Calibration of the JAGB Method Using Gaia EDR3
Madore, Barry F.; Freedman, Wendy L.; Lee, Abigail J. +2 more
The recently developed J-region asymptotic giant branch (JAGB) method has extraordinary potential as an extragalactic standard candle, capable of calibrating the absolute magnitudes of locally accessible Type Ia supernovae, thereby leading to an independent determination of the Hubble constant. Using Gaia Early Data Release 3 (EDR3) parallaxes, we…
Gas Infalling Motions in the Envelopes of Very Low Luminosity Objects
Kim, Gwanjeong; Kim, Mi-Ryang; Lee, Chang Won +2 more
We present the results of a single-dish survey toward 95 very low luminosity objects (VeLLOs) in optically thick (HCN 1-0) and thin (N2H+ 1-0) lines performed for the purpose of understanding the physical processes of inward motions in the envelopes of the VeLLOs and characterizing their true nature. The normalized velocity d…
The Stellar Initial Mass Function and Population Properties of M89 from Optical and NIR Spectroscopy: Addressing Biases in Spectral Index Analysis
Freedman, Wendy L.; Feldmeier-Krause, A.; Lonoce, I.
The complexity of constraining the stellar initial mass function (IMF) in early-type galaxies cannot be overstated, given the necessity of very high signal-to-noise ratio (S/N) data and the difficulty of breaking the strong degeneracies that occur among several stellar population parameters, including age, metallicity, and elemental abundances. Wi…
NOEMA Redshift Measurements of Extremely Bright Submillimeter Galaxies near the GOODS-N
Cowie, Lennox L.; Barger, Amy J.; Jones, Logan H. +1 more
We report spectroscopic redshift measurements for three bright submillimeter galaxies (SMGs) near the GOODS-N field, each with SCUBA-2 850 µm fluxes >10 mJy, using the Northern Extended Millimeter Array (NOEMA). Our molecular line-scan observations of these sources, which occupy an ~7 arcmin2 area outside of the Hubble Space Te…
On the Possibility of Stellar Lenses in the Black Hole Candidate Microlensing Events MACHO-96-BLG-5 and MACHO-98-BLG-6
Lu, Jessica R.; Abdurrahman, Fatima N.; Stephens, Haynes F.
Although stellar-mass black holes (BHs) are likely to be abundant in the Milky Way (N = 108-109), only 20 have been detected to date, all in accreting binary systems. Gravitational microlensing is a proposed technique to search for isolated BHs, which have not yet been detected. Two specific microlensing events, MACHO-1996-BL…
Two Populations of Carbon-enhanced Metal-poor Stars in the Disk System of the Milky Way
Yoon, Jinmi; Beers, Timothy C.; Lee, Young Sun +2 more
We present a chemodynamical analysis of low-resolution (R ~ 1300) spectroscopy of ~50,000 stars from the AAOmega Evolution of Galactic Structure survey, focusing on two key populations of (in total) 650 carbon-enhanced metal-poor (CEMP) stars within the disk system of the Milky Way: a mildly prograde population (Lz < 1000 kpc km s
Improved Measurements of Molecular Cloud Distances Based on Global Search
Wang, Hongchi; Xu, Ye; Su, Yang +5 more
The principle of the background-eliminated extinction-parallax (BEEP) method is examining the extinction difference between on- and off-cloud regions to reveal the extinction jump caused by molecular clouds, thereby revealing the distance in complex dust environments. The BEEP method requires high-quality images of molecular clouds and high-precis…
Chandra Observations of Excess Fe Kα Line Emission in Galaxies with High Star Formation Rates: X-Ray Reflection on Galaxy Scales?
Ricci, Claudio; Bauer, Franz E.; Hickox, Ryan C. +4 more
In active galactic nuclei (AGNs), fluorescent Fe Kα (iron) line emission is generally interpreted as originating from obscuring material around a supermassive black hole on the scale of a few parsecs. However, recent Chandra studies indicate the existence of iron line emission extending to kiloparsec scales in the host galaxy. The connection betwe…
Variation in the Stellar Initial Mass Function from the Chromospheric Activity of M Dwarfs in Early-type Galaxies
van Dokkum, Pieter; Conroy, Charlie
Mass measurements and absorption-line studies indicate that the stellar initial mass function (IMF) is bottom-heavy in the central regions of many early-type galaxies, with an excess of low-mass stars compared to the IMF of the Milky Way. Here we test this hypothesis using a method that is independent of previous techniques. Low-mass stars have st…