Polis - μ Sagittarii (mu Sagittarii)

Altitude: -47.0° Azimuth: 300.0° Direction: West-North-West

Polis, also designated as μ Sagittarii (mu Sagittarii), is a variable and multiple supergiant star in the constellation of Sagittarius.

Polis visual magnitude is 3.86. Because of its moderate brightness, Polis 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 Polis:

Color of Polis ⬤

Magnitude of Polis 3.86

Class Supergiant

VISIBILITY RIGHT NOW

Polis - μ Sagittarii (mu Sagittarii) is below the horizon from Greenwich, United Kingdom edit_location_alt.

Altitude: -47.0°
Azimuth: 300.0°
Direction: West-North-West

Celestial coordinates and finder chart of Polis

Polis is situated close to the celestial equator, as such, it is at least partly visible from both hemispheres in certain times of the year. Celestial coordinates for the J2000 equinox as well as galactic coordinates of Polis are provided in the following table:

Right Ascension J2000 18h 13m 45s

Declination J2000 -21° 03’ 32”

Galactic Longitude 10°

Galactic Latitude -1.6°

Constellation Sagittarius

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

Finder chart Polis - μ Sagittarii (mu Sagittarii) star

Simplified finder chart for Polis - μ Sagittarii (mu Sagittarii).

Visibility of Polis 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 Polis - μ Sagittarii (mu Sagittarii) 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: 111.1° RISE 21:54

Max altitude: 17.5° TRANSIT 2:01

Azimuth: 248.9° SET 6:04

RIGHT NOW Polis - μ Sagittarii (mu Sagittarii) is below the horizon from Greenwich, United Kingdom

Digitized Sky Survey image of Polis

The image below is a photograph of Polis 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 Polis is 0.002 arcsec per year in Right Ascension and 0.001 arcsec per year in Declination and the associated displacement for the next 100000 years is represented with the red arrow.

Image of Polis - μ Sagittarii (mu Sagittarii) star

DSS2 image of Polis. The red arrow shows the motion of Polis during the next 100000 years (3.33 arcmin in Right Ascension and 1.67 arcmin in declination);

Distance of Polis from the Sun and relative movement

Polis is distant 29,636.36 light years from the Sun and it is moving towards the Sun at the speed of 6 kilometers per second.

Distance (parsec) 9,090.91 pc

Distance (light year) 29,636.36 ly

Heliocentric radial velocity -6 km/s

Proper Motion RA 0.002 arcsec/year

Proper Motion Dec 0.001 arcsec/year

Spectral properties of Polis

Polis belongs to spectral class B8 and has a luminosity class of I corresponding to a supergiant star.

Absolute magnitude -10.93

Spectral Type B8I

Color Index (B-V) 0.23

Temperature of Polis 7938K

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

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

Polis star system properties

Polis is a visual double star which can be observed only with the help of very large telescopes. The table below shows key information about the Polis double sysyem:

Main star magnitude 3.86

Secondary star magnitude 6.76

Magnitude difference 2.9

Separation 0 arcsec

Alternative designations of Polis

Proper Name Polis

Bayer designation μ Sagittarii
(mu Sagittarii)

Flamsteed designation 13 Sagittarii

Henry Draper Catalogue HD166937

SAO Catalogue SAO186497

Hipparcos Catalogue HIP89341

Durchmusterung Catalogue BD-21 4908

FK5 Catalogue 682

General Catalogue of Variable Stars Mu Sgr

Aitken Double Star Catalogue ADS11169

In Evidence

Other stars in Sagittarius