The Next ASLC Meeting is:
April 25, 2014 @ 7:30 pm
Speaker: Carlos Vargas
To Stack or not to Stack: Lessons from z=2.1 Lyman Alpha Emitting Galaxies
Location: Dona Ana Community College
Room 141 (map)
Contact the Club President for additional information
Upcoming Observing Opportunities:
(Int'l Delights Cafe)
Sat, April 5th (dusk)
Monthly Dark Sky Viewing
Sat, April 26th (dusk)
Greetings from the professional and amateur astronomers who comprise the Astronomical Society of Las Cruces (ASLC). The club was formed in 1951 by a group of dedicated astronomers including Clyde Tombaugh, who had discovered Pluto just 21 years earlier. For over 60 years, we've been sharing a little bit of the universe with our community under our beautiful Southern New Mexico skies.
The club has a variety of ongoing observing, education and public outreach programs. We host a public Moongaze each month, offer beginning astronomy courses and support countless star parties for schools, scouts and various organizations. We also hold a meeting each month which includes a featured presentation.
To learn more about our society, please click here or select from the tabs above or the 'Quick Links' on the left.
The monthy ASLC meeting will be held on Friday, April 25th at 7:30PM. Carlos Vargas will give a talk entitled: "To Stack or not to Stack: Lessons from z=2.1 Lyman Alpha Emitting Galaxies". Carlos is a PhD student in the NMSU Dept. of Astronomy. The following is a summary of Carlos' presentation.
We use the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS) GOODS-S multi-wavelength catalog to identify counterparts for 20 Lyα emitting (LAE) galaxies at z = 2.1. We build several types of stacked spectral energy distributions (SEDs) of these objects. We combine photometry to form average and median flux-stacked SEDs, and postage-stamp images to form average and median image-stacked SEDs. We also introduce scaled flux stacks that eliminate the influence of variation in overall brightness. We use the SED fitting code SpeedyMC to constrain the physical properties of individual objects and stacks. Our LAEs at z = 2.1 have stellar masses ranging from 2 × 107 M ⊙ to 8 × 109 M ⊙ (median = 3 × 108 M ⊙), ages ranging from 4 Myr to 500 Myr (median = 100 Myr), and E(B - V) between 0.02 and 0.24 (median = 0.12). Although still low, this represents significantly more dust reddening than has been reported for LAEs at higher redshifts.The SED parameters of the flux stacks match the average and median values of the individual objects, with the flux-scaled median SED performing best with uncertainties reduced by a factor of two. Median image-stacked SEDs provide a poor representation of the median individual object, and none of the stacking methods capture the large dispersion of LAE properties.
ASLC Photo of the Week - M46 by Chuck Sterling
Open Cluster M46 is in constellation Puppis. M46 is about 5,500 light-years away with an estimated age on the order of several hundred million years. The planetary nebula NGC 2438 appears to lie within the cluster near its northern edge (the faint doughnut at the right center of the cluster). NGC 2438 is most likely unrelated since it does not share the cluster's radial velocity, and just happens to be in the same field of view.
The image was acquired from his back yard in Las Cruces, NM, using Images Plus Camera Control 2.0 with a Canon 350d camera on an Astro Tech 8" f/4 imaging newtonian, with an IDAS LPS-P1 light pollution filter and a Baader MPCC (multi-purpose coma corrector). The mount is a Celestron CGE, autoguided by PHDGuide 1.12.3 and a ShoeString Astronomy GPUSB with a Meade DSI-Pro-1 camera on an Orion 80ED f/7.5 refractor.
Clicking on the image will take you to a larger version on Chuck's website.
The Astronomical Society of Las Cruces is a proud member of the Astronomical League
ASLC supports the eradication of light pollution by its participation in the International DarkSky Association
ASLC works with local teaching professionals using instructional resources provided by Project Astro