Moons page — updated on February 16th, 2017

Thursday, March 30, 2017

Hercules Constellation

Constellation map or sky chart of Hercules and surrounding constellations

Symbol of Hercules, derived from the illustrative work of Denis Moskowitz and Alec Finlay at Suberic.netMicrosoft Clip Art of the Hercules constellation
In proximity to the dense Milky Way band that is visible from Earth, HERCULES the Hero — the Roman name for the same Heracles character in Greek mythology — is a predominantly Northern Hemisphere constellation named after Jupiter's (Greek mythology: Zeus') heroic son. Hercules is the night sky's fifth-largest constellation and is one of 48 constellations to be listed by Ptolemy in his Almagest astronomical treatise. This vast constellation is surrounded by the following constellations: Aquila, Boötes, Corona Borealis, Draco, Lyra, Ophiuchus, Sagitta, Serpens Caput, Ursa Major, and Vulpecula.

Exoplanets seem to be discovered every day, and Hercules is home to at least twelve (12) confirmed stars with planets encircling them as of 2017. Two globular star clusters dominate over most other deep-sky objects within Hercules. Visible to the naked eye at apparent magnitude 5.8, Messier 13 (M13 and NGC 6205) boasts the designation of being the Northern Hemisphere's brightest globular cluster. This NASA Astronomy Picture of the Day (↗) reveals M13's brilliant blue, green, white, and yellow stars. Another daily photo (↗) depicts Comet Garradd traversing in February 2012 past Messier 92 (M92 and NGC 6341), Hercules' other prominent globular cluster. Other notable deep-sky wonders include the spiral-galaxy-filled Hercules Galaxy Cluster (Abell 2151), Abell 2199 galaxy cluster, Arp 272 interacting galaxies, circular Abell 39 planetary nebula, and NGC 6210 planetary nebula. More details about Hercules and its features can be found on the Constellation Guide website (↗).

Click on the images below to enlarge them to full size.

M13 globular star cluster, central area in the Hercules constellation       Hercules Cluster (Abell 2151) featuring mostly spiral galaxies

Hercules A radio source and its associated galaxy       NGC 6210 planetary nebula, located about 6,500 light years away in the southern section of Hercules

Image Credits (top-left, clockwise)
M13: NASA APOD (↗) — Marco Burali, Tiziano Capecchi, and Marco Mancini (Osservatorio MTM)
Hercules Cluster: NASA APOD (↗) — Ken Crawford
NGC 6210: Hubble Space Telescope (↗) — NASA and ESA
Hercules A: Hubble Space Telescope (↗) — NASA and ESA

Brightest Star: Kornephoros, Beta Herculis (β); 2.78 apparent magnitude

2nd-Brightest Star: Rasalgethi (Ras Algethi), Alpha Herculis (α); 2.78-3.35 apparent magnitude

Galaxies: Abell 2199 galaxy cluster (~300 galaxies), Hercules Cluster/Abell 2151 (~200 galaxies), Arp 272 interacting galaxies (IC 1179 and NGC 6050), and "supermassive" elliptical NGC 6166

Globular Star Clusters: Messier 13 (NGC 6205), Messier 92 (NGC 6341), and NGC 6229

Planetary Nebulae: Abell 39, IC 4593, and NGC 6210

Radio Source: Hercules A in the 3C 348 galaxy

Variable Stars: 30 Herculis, 68 Herculis, OP Herculis, U Herculis, and X Herculis
       — Binary Variable Star: Rasalgethi (Ras Algethi); three stars orbit each other, and one star is variable

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Blog Background

The background has three Hubble Space Telescope images, which are accessible at this Hubble webpage:

— LH 95 is a star-forming region in the Large Magellanic Cloud, Dorado constellation.

— Ant Nebula (also called Menzel 3) is an aptly-named planetary nebula located in the constellation Norma.
— Egg Nebula (also called CL 2688) is a protoplanetary nebula in the constellation Cygnus.

HubbleSite Image Links: LH 95, Ant Nebula, and Egg Nebula