Your Guide to the Solar System and the Night Sky
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public Observing fromLocation: Greenwich, United Kingdom edit_location_alt
north SunriseRise: 4:52  
clear_day Transit: 12:55  
SunsetSet: 20:59 south
wb_twilight Astronomical TwilightWhat's Visible Now
All Constellations » Hydra » 


HR3931 is a double main-sequence star in the constellation of Hydra.

HR3931 visual magnitude is 6.28. Because of its reltive faintness, HR3931 should be visible only from locations with dark skyes, while it is not visible at all from skyes affected by light pollution.

The table below summarizes the key facts about HR3931:

HR3931 is below the horizon from Greenwich, United Kingdom edit_location_alt.

Celestial coordinates and finder chart of HR3931

HR3931 is situated south of the celestial equator, as such, it is more easily visible from the southern hemisphere. Celestial coordinates for the J2000 equinox as well as galactic coordinates of HR3931 are provided in the following table:

09h 56m 46s
-26° 33’ 01”

The simplified sky map below shows the position of HR3931 in the sky:

Finder chart HR3931 star
Simplified finder chart for HR3931.

Visibility of HR3931 from your location

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

Today's HR3931 rise, transit and set times from Greenwich, United Kingdom edit_location_alt are the following (all times relative to the local timezone Europe/London):

Azimuth: 116.6°
Max altitude: 12.0°
Azimuth: 243.4°
HR3931 is below the horizon from Greenwich, United Kingdom

Digitized Sky Survey image of HR3931

The image below is a photograph of HR3931 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 HR3931 is -0.114 arcsec per year in Right Ascension and 0.006 arcsec per year in Declination and the associated displacement for the next 1000 years is represented with the red arrow.

Image of HR3931 star
DSS2 image of HR3931. The red arrow shows the motion of HR3931 during the next 1000 years (-1.90 arcmin in Right Ascension and 0.10 arcmin in declination);

Distance of HR3931 from the Sun and relative movement

HR3931 is distant 226.55 light years from the Sun and it is moving far from the Sun at the speed of 11 kilometers per second.

69.49 pc
226.55 ly
11 km/s
-0.114 arcsec/year
0.006 arcsec/year

Spectral properties of HR3931

HR3931 belongs to spectral class A4 and has a luminosity class of V corresponding to a main-sequence star.


The red dot in the diagram below shows where HR3931 is situated in the Hertzsprung–Russell diagram.

HR Diagram
H-R diagram showing the position of HR3931. Attribution: Richard Powell / CC BY-SA

HR3931 star system properties

HR3931 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 HR3931 double sysyem:

3.4 arcsec

Alternative designations of HR3931