Erratum: “A High-resolution Multiband Survey of Westerlund 2 with the Hubble Space Telescope. III. The Present-day Stellar Mass Function” (2017, AJ, 153, 122)

2020 ◽  
Vol 159 (3) ◽  
pp. 127
Author(s):  
Peter Zeidler ◽  
Antonella Nota ◽  
Eva K. Grebel ◽  
Elena Sabbi ◽  
Anna Pasquali ◽  
...  
2017 ◽  
Vol 153 (3) ◽  
pp. 122 ◽  
Author(s):  
Peter Zeidler ◽  
Antonella Nota ◽  
Eva K. Grebel ◽  
Elena Sabbi ◽  
Anna Pasquali ◽  
...  

2020 ◽  
Vol 501 (2) ◽  
pp. 1568-1590
Author(s):  
Lukas J Furtak ◽  
Hakim Atek ◽  
Matthew D Lehnert ◽  
Jacopo Chevallard ◽  
Stéphane Charlot

ABSTRACT We present new measurements of the very low mass end of the galaxy stellar mass function (GSMF) at z ∼ 6−7 computed from a rest-frame ultraviolet selected sample of dropout galaxies. These galaxies lie behind the six Hubble Frontier Field clusters and are all gravitationally magnified. Using deep Spitzer/IRAC and Hubble Space Telescope imaging, we derive stellar masses by fitting galaxy spectral energy distributions and explore the impact of different model assumptions and parameter degeneracies on the resulting GSMF. Our sample probes stellar masses down to $M_{\star }\gt 10^{6}\, \text{M}_{\odot}$ and we find the z ∼ 6−7 GSMF to be best parametrized by a modified Schechter function that allows for a turnover at very low masses. Using a Monte Carlo Markov chain analysis of the GSMF, including accurate treatment of lensing uncertainties, we obtain a relatively steep low-mass end slope $\alpha \simeq -1.96_{-0.08}^{+0.09}$ and a turnover at $\log (M_T/\text{M}_{\odot})\simeq 7.10_{-0.56}^{+0.17}$ with a curvature of $\beta \simeq 1.00_{-0.73}^{+0.87}$ for our minimum assumption model with constant star formation history (SFH) and low dust attenuation, AV ≤ 0.2. We find that the z ∼ 6−7 GSMF, in particular its very low mass end, is significantly affected by the assumed functional form of the star formation history and the degeneracy between stellar mass and dust attenuation. For example, the low-mass end slope ranges from $\alpha \simeq -1.82_{-0.07}^{+0.08}$ for an exponentially rising SFH to $\alpha \simeq -2.34_{-0.10}^{+0.11}$ when allowing AV of up to 3.25. Future observations at longer wavelengths and higher angular resolution with the James Webb Space Telescope are required to break these degeneracies and to robustly constrain the stellar mass of galaxies on the extreme low-mass end of the GSMF.


2020 ◽  
Author(s):  
Joe Zalesky ◽  
Michael Line ◽  
Matteo Brogi

<p>High Resolution Cross Correlation Spectroscopy (HRCCS) has become a powerful tool to constrain both the physical characteristics and abundances of atomic/molecular constituents in exoplanetary atmospheres. Brogi & Line (2019) recently introduced a novel Bayesian atmospheric retrieval methodology that can combine observations from both longer wavelength (2-4 micron), ground-based, HRCCS and shorter wavelength (1-2 micron) space-based observatories such as the Hubble Space Telescope (HST). Here we present results from the application of this technique to both new and previously published observations of HD209458b and HD189733b from VLT/CRIRES, HST, and Spitzer. The more complete wavelength coverage provides a more comprehensive assessment of the atmosphere by way of stronger constraints on the thermal profiles, atmospheric metallicity, and carbon/oxygen inventory for these two benchmark planets. We also investigate the impact of possible model-induced biases including assumptions regarding molecular cross-sections, cloud model prescriptions, and thermal profile parameterizations. Finally, we present what constraints may be possible in the future by performing retrievals of synthetic observations from the next generation of high-resolution spectrographs like CRIRES+. This work has laid a foundational dataset that combines both space and ground-based observations to comprehensively characterize exoplanetary atmospheres and will be a useful benchmark in comparison to future efforts for both transiting and non-transiting atmospheric characterization.</p>


2002 ◽  
Vol 207 ◽  
pp. 306-308
Author(s):  
R. Buta ◽  
M. L. McCall

The Hubble Space Telescope Wide Field and Planetary Camera 2 was used to image at high resolution the core region of the nearby, heavily obscured massive elliptical galaxy Maffei 1. We report on the discovery of 19 diffuse objects in the WFPC2 field that are likely to be globular clusters associated with Maffei 1. We present some preliminary data on the luminosities, colors, and sizes of these candidates.


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