Senkyo Is Equatorial Dark Albedo Feature on Titan's Saturn-Facing Side

Summary: Senkyo is an equatorial dark albedo feature on Titan's Saturn-facing side that forms a low albedo quartet with Aaru, Aztlan and Fensal.

image of dark albedo duo of Senkyo (right center) and Aaru (above), obtained Dec. 12, 2008, by Cassini spacecraft's Narrow-Angle Camera (NAC), using a spectral filter with sensitivity to 938 nanometer-centered near-infrared light wavelengths; image obtained at an approximate distance of 2.361 million kilometers (1.467 million miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 26 degrees; image addition date 2009-01-27; image credit NASA/JPL/Space Science Institute: May be used for any purpose without prior permission, via NASA JPL Photojournal

Senkyo is an equatorial dark albedo feature on Titan's Saturn-facing side that forms an equatorial quartet of low albedo, or low reflectance, with the three optically dark neighboring regions of Aaru, Aztlan and Fensal.

Senkyo is centered at minus 5 degrees south latitude, 320 degrees west longitude, according to the International Astronomical Union’s (IAU) Gazetteer of Planetary Nomenclature. The Gazetteer repeats the optically dark albedo feature's center latitude and longitude as its northernmost and southernmost latitudes and its easternmost and westernmost longitudes, respectively.

Senkyo's far western longitudinal location in Titan's equatorial belt allows the low reflector to cluster with three dark, equatorial neighbors. Southern equatorial-centered Senkyo presents a dark quartet with northern equatorial-centered Aaru and Aztlan and southern equatorial-centered Fensal.

Aaru is centered to the northwest of Senkyo in Titan's northern equatorial belt. Aaru's center latitude and longitude are 10 degrees north and 340 degrees west, respectively.

Fensal is centered to the northeast of Senkyo in Titan's northern equatorial belt. The dark albedo feature records center coordinates of 5 degrees north latitude, 30 degrees west longitude.

Aztlan is centered to the southeast of Senkyo in Titan's southern equatorial belt. The lower reflector registers minus 10 degrees south as its center latitude and 20 degrees west longitude as its center longitude.

The quartet's prominent darkness in Titan's equatorial belt appears to represent "vast and continuous dune fields," according to NASA Jet Propulsion Laboratory's (JPL) Photojournal website's post, "Saturn's View of Titan," published July 28, 2006. The extensive, dark, dune landforms are composed of solid hydrocarbon particles that precipitated from Titan's smoggy atmosphere, according to Photojournal's "Spying on Senkyo," published April 8, 2013. An unknown process has aggregated the hydrocarbon particles into 0.04-inch grains, according to NASA JPL editor and writer Jia-Rui C. Cook's post, "Cassini Sees the Two Faces of Titan's Dunes," published Jan. 23, 2012, on the NASA website's Cassini-Huygens mission pages.

The dunes that are responsible for the equatorial quartet's low albedo occur as Titan's second most dominant landform, outnumbered only by plains. Dunes cover an area of 4 million square miles (10 million square kilometers), which equates to about 13 percent of Titan's surface, according to Cook's post. Titan's dunes are found only in the moon's equatorial belt, between 30 degrees north latitude and 30 degrees south latitude.

Bright plateaus border Senkyo's dune-filled plains, according to planetary scientist Bonnie J. Buratti and nine co-authors in their article, "A Newly Discovered Impact Crater in Titan's Senkyo," published in the January 2012 issue of Planetary and Space Science. During the Cassini spacecraft's T61 flyby, conducted Aug. 25, 2009, the spacecraft's onboard Visual and Infrared Mapping Spectrometer (VIMS) observed a circular feature with center coordinates of 5.4 degrees north latitude, 341 degrees west longitude. The unknown feature superimposed Senkyo's low albedo dunes and one of the surrounding, high albedo plateaus. The authors note Paxsi as the newly discovered landform's official name.

Paxsi nudges Senkyo's northern neighbor, Aaru, with its location in the brightly reflective terrain that interrupts the equatorial belt's dark expanses. Paxsi is centered at 5 degrees north latitude, 341.2 degrees west longitude, according to the Gazetteer of Planetary Nomenclature. The circular feature registers northernmost and southernmost latitudes of 6.7 degrees north and 3.7 degrees north, respectively. It obtains its easternmost and westernmost longitudes at 339.8 degrees west and 342.6 degrees west, respectively. Paxsi's diameter measures 120 kilometers.

The International Astronomical Union's convention for Titan's albedo features calls for names, presented in the world's cultural legends, myths, poems and stories, for "Sacred or enchanted places, paradise, or celestial realms." The IAU approved Senkyo's name in 2006. The Gazetteer of Planetary Nomenclature identifies the name's origin in the "Japanese ideal realm of aloofness and serenity, freedom from worldly cares and death."

Senkyo's Titanean environment, however, appears as "less welcoming" than a Japanese paradise, according to NASA JPL Photojournal's "Frozen Paradise," published March 2, 2015. Titan's average temperature approximates minus 290 degrees below zero Fahrenheit (minus 180 degrees Celsius). The inhospitable temperature freezes water to rock-hardness.

A break in Titan's clouds reveals optically dark albedo feature Senkyo; image obtained Oct. 12, 2009, by Cassini spacecraft's Narrow-Angle Camera (NAC), using a spectral filter with sensitivity to 938 nanometer-centered near-infrared light wavelengths; image acuired at an approximate distance of 296,000 kilometers (184,000 miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 11 degrees; image addition date 2009-12-02; image credit NASA/JPL/Space Science Institute: May be used for any purpose without prior permission, via NASA JPL Photojournal Astrogeology Science Center's Gazetteer of Planetary Nomenclature

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

image of dark albedo duo of Senkyo (right center) and Aaru (above), obtained Dec. 12, 2008, by Cassini spacecraft's Narrow-Angle Camera (NAC), using a spectral filter with sensitivity to 938 nanometer-centered near-infrared light wavelengths; image obtained at an approximate distance of 2.361 million kilometers (1.467 million miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 26 degrees; image addition date 2009-01-27; image credit NASA/JPL/Space Science Institute: May be used for any purpose without prior permission, via NASA JPL Photojournal @ https://photojournal.jpl.nasa.gov/catalog/PIA10565

A break in Titan's clouds reveals optically dark albedo feature Senkyo; image obtained Oct. 12, 2009, by Cassini spacecraft's Narrow-Angle Camera (NAC), using a spectral filer with sensitivity to 938 nanometer-centered near-infrared light wavelengths; image acuired at an approximate distance of 296,000 kilometers (184,000 miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 11 degrees; image addition date 2009-12-02; image credit NASA/JPL/Space Science Institute: May be used for any purpose without prior permission, via NASA JPL Photojournal @ https://photojournal.jpl.nasa.gov/catalog/PIA11636; via NASA Image and Video Library @ https://images.nasa.gov/details-PIA11636

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