42 Herculis

42 Herculis is a variable and double giant star in the constellation of Hercules.

42 Herculis visual magnitude is 4.9. Because of its moderate brightness, 42 Herculis should be easily visible from locations with dark skyes, while it can be barely visible, or not visible at all, from skyes affected by light pollution.

The table below summarizes the key facts about 42 Herculis:

Color of 42 Herculis ⬤

Magnitude of 42 Herculis 4.9

Class Giant

VISIBILITY RIGHT NOW 42 Herculis is above the horizon from Greenwich, United Kingdom [change]. Altitude: 27°.

Celestial coordinates and finder chart of 42 Herculis

42 Herculis is situated north of the celestial equator, as such, it is more easily visible from the northern hemisphere. Celestial coordinates for the J2000 equinox as well as galactic coordinates of 42 Herculis are provided in the following table:

Right Ascension J2000 16h 38m 44s

Declination J2000 +48° 55’ 41”

Galactic Longitude 75.61°

Galactic Latitude 41.58°

Constellation Hercules

The simplified sky map below shows the position of 42 Herculis in the sky:

Simplified finder chart for 42 Herculis.

Visibility of 42 Herculis from your location

Location: Greenwich, United Kingdom [change]
Latitude: 51° 28’ 47” N
Longitude: 0° 00’ 00” E
Timezone: Europe/London

42 Herculis is circumpolar and transits at 04:17 UTC (altitude: 87.4°)

Digitized Sky Survey image of 42 Herculis

The image below is a photograph of 42 Herculis from the Digitized Sky Survey 2 (DSS2 - see the credits section) taken in the red channel. The area of sky represented in the image is 0.5x0.5 degrees (30x30 arcmins). The proper motion of 42 Herculis is -0.047 arcsec per year in Right Ascension and 0.031 arcsec per year in Declination and the associated displacement for the next 10000 years is represented with the red arrow.

DSS2 image of 42 Herculis. The red arrow shows the motion of 42 Herculis during the next 10000 years (-7.83 arcmin in Right Ascension and 5.17 arcmin in declination);

Distance of 42 Herculis from the Sun and relative movement

42 Herculis is distant 376.01 light years from the Sun and it is moving towards the Sun at the speed of 55 kilometers per second.

Distance (parsec) 115.34 pc

Distance (light year) 376.01 ly

Heliocentric radial velocity -55 km/s

Proper Motion RA -0.047 arcsec/year

Proper Motion Dec 0.031 arcsec/year

Spectral properties of 42 Herculis

42 Herculis belongs to spectral class M2 and has a luminosity class of III corresponding to a giant star.

Absolute magnitude -0.41

Spectral Type M2III

Color Index (B-V) 1.55

Temperature of 42 Herculis 3720K

The red dot in the diagram below shows where 42 Herculis is situated in the Hertzsprung–Russell diagram.

H-R diagram showing the position of 42 Herculis. Attribution: Richard Powell / CC BY-SA

42 Herculis star system properties

42 Herculis is a visual double star which can be observed with the help of small or medium telescopes. The table below shows key information about the 42 Herculis double sysyem:

Main star magnitude 4.9

Secondary star magnitude 10.3

Magnitude difference 5.4

Separation 25.6 arcsec

Alternative designations of 42 Herculis

Flamsteed designation 42 Herculis

Henry Draper Catalogue HD150450

SAO Catalogue SAO46210

Hipparcos Catalogue HIP81497

Durchmusterung Catalogue BD+49 2531

FK5 Catalogue 1434

General Catalogue of Variable Stars 7896

Aitken Double Star Catalogue ADS10144

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In Evidence

Other stars in Hercules