From the November 2017 issue

Are there 3-D renderings of the Small and Large Magellanic Clouds available to view?

Patrick Clough Wichita, Kansas
By | Published: October 3, 2017
The Large (upper right) and Small (lower left) Magellanic Clouds orbit the Milky Way at a distance of 160,000 light-years and 200,000 light-years, respectively. Even at these distances, the two satellite galaxies are close enough for astronomers to resolve and study individual stars.
ESO/S. Brunier
The Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC), satellite galaxies of the Milky Way, are close enough that astronomers can resolve these dwarf galaxies into their individual stars. Several projects exist to study — and subsequently map — the clouds’ stellar populations and their distances. However, no such renderings using current data are available for public use as of yet.

To map the Magellanic Clouds, many studies have used variable stars, namely Cepheid and RR Lyrae variables, to determine the distances to these stars within the LMC and SMC quite accurately. These variable stars are such accurate distance indicators because they display a clear correlation between their pulsation periods and their intrinsic brightnesses. By measuring a star’s light curve and determining the period of time over which it varies, astronomers can calculate the star’s intrinsic brightness and compare it to observations. Any dimming of the star with respect to the brightness we expect to see is thus related to the star’s distance.

Over time, increasing the catalogs of these variables and others within the Magellanic Clouds has begun to reveal their 3-D structure. From these measurements, astronomers have already determined that the SMC is highly elongated along our line of sight, stretching away from us with a length between 32,600 and 65,200 light-years. Overall, the SMC’s shape can be described as an “extended ellipsoid,” while the LMC appears to have a central bar structure and at least one spiral arm.

Alison Klesman  
Associate Editor