scholarly journals Model for Infrared Properties of Extremely Young Galaxies

2004 ◽  
Vol 217 ◽  
pp. 214-215
Author(s):  
T. T. Takeuchi ◽  
H. Hirashita ◽  
T. T. Ishii ◽  
L. K. Hunt ◽  
A. Ferrara

We constructed a model of the infrared spectral energy distribution for very young galaxies by taking into account the dust size distribution in the early stage of galaxy evolution.

2013 ◽  
Vol 8 (S299) ◽  
pp. 330-331
Author(s):  
Mark Booth ◽  
Grant Kennedy ◽  
Bruce Sibthorpe ◽  
Brenda C. Matthews ◽  
Mark C. Wyatt ◽  
...  

AbstractUsing photometry at just two wavelengths it is possible to fit a blackbody to the spectrum of infrared excess that is the signature of a debris disc. From this the location of the dust can be inferred. However, it is well known that dust in debris discs is not a perfect blackbody. By resolving debris discs we can find the actual location of the dust and compare this to that inferred from the blackbody fit. Using the Herschel Space Observatory we resolved many systems as part of the DEBRIS survey. Here we discuss a sample of 9 discs surrounding A stars and find that the discs are actually located between 1 and 2.5 times further from their star than predicted by blackbody fits to the spectral energy distribution (SED). The variation in this ratio is due to differences in stellar luminosities, location of the dust, size distribution and composition of the dust.


2011 ◽  
Vol 10 (4) ◽  
pp. 307-313 ◽  
Author(s):  
Duncan H. Forgan ◽  
Martin Elvis

AbstractThe development of civilizations such as ours into spacefaring, multi-planet entities requires significant raw materials to construct vehicles and habitats. Interplanetary debris, including asteroids and comets, may provide such a source of raw materials. In this article, we present the hypothesis that extraterrestrial intelligences (ETIs) engaged in asteroid mining may be detectable from Earth. Considering the detected disc of debris around Vega as a template, we explore the observational signatures of targeted asteroid mining (TAM), such as unexplained deficits in chemical species, changes in the size distribution of debris and other thermal signatures that may be detectable in the spectral energy distribution (SED) of a debris disc. We find that individual observational signatures of asteroid mining can be explained by natural phenomena, and as such they cannot provide conclusive detections of ETIs. But, it may be the case that several signatures appearing in the same system will prove harder to model without extraterrestrial involvement. Therefore, signatures of TAM are not detections of ETI in their own right, but as part of ‘piggy-back’ studies carried out in tandem with conventional debris disc research, they could provide a means of identifying unusual candidate systems for further study using other search for extra terrestrial intelligence (SETI) techniques.


2012 ◽  
Vol 8 (S289) ◽  
pp. 292-295
Author(s):  
Ralf Kotulla

AbstractPhotometric redshifts, i.e. redshifts derived by comparing an observed spectral-energy distribution (SED) to a range of empirical or theoretical SED templates, are commonly used in studies of the high-redshift Universe. Often, the next step is to use these redshifts as fixed input parameters for SED fitting to derive physical properties for each galaxy. However, this two-step approach ignores degeneracies between redshift and, e.g., stellar mass. Here I present first results using an improved approach that integrates both methods. I find that mass determinations are, on average, three times more uncertain than they seem from the common two-step approach. If not accounted for, these underestimated uncertainties can impact our ability of making meaningful comparisons between observations and simulations of galaxy evolution.


2013 ◽  
Vol 764 (2) ◽  
pp. 159 ◽  
Author(s):  
Paulina Lira ◽  
Liza Videla ◽  
Yanling Wu ◽  
Almudena Alonso-Herrero ◽  
David M. Alexander ◽  
...  

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