Stars in 3D: Overview

Introduction

There are over 100 billion stars in our Milky Way galaxy. Galaxies3D explores two extremes:

 

The Brightest Stars and their Spiral Arm

In showing the brighest stars in 3D, Galaxies3D makes extensive use of an image of the Milky Way Galaxy by Robert Hurt of NASA and JPL-Caltech, presented at the 212th American Astronomical Society meeting. The image is used to help make clear:

The NASA/JPL-Caltech map, based on data from the Spitzer Space Telescope, shows the Milky Way with:

The Sun lies in a small "spur" or branch arm off the Sagittarius Spiral Arm — the Orion Spur, sometimes also called the Orion Arm. That very small circle marking the position of the Sun in the Orion Spur has a radius of approximately 750 light years. The lines of galactic longitude radiate from the Sun across the vast galactic disk:

The Galactic Disc

from Milky Way Galaxy annotated, by Robert Hurt of NASA and JPL-Caltech

In front of the Sun in the Orion Spur, towards the galactic center, is the Sagittarius Spiral Arm. In front of the Saggittarius arm lies the large Scutum-Centaurus Spiral Arm. Behind the Sun in the Orion Spur, away from the galactic center, lies the large Perseus Spiral Arm:

portion of galactic disc near the Orion Spur

The majority of bright stars we see from Earth lie within that small 750 light year radius circle marking the sun in the above images. The Galactic center lies about 26,000 light years from the sun, so the 750 light year radius is about 2.9% of the way to the Galactic center.

To put some numbers on the comment about "the majority" of stars, in exploring the stars of each constellation, Galaxies3D includes all stars brighter than visual magnitude 4.5 — about 925 stars. This magnitude limit includes nearly:

At this limit, 815 visible stars lie within the 750 light year radius circle marking the Sun's position. 110 stars (about 12%) lie outside the circle, most lying within 2000 light years of the Sun and well within the Orion Spur. The notable exceptions are labeled in the image below from Galaxies3D of stars brighter than magnitude 4.5, and farther than 750 light years:

Stars brighter than mag 4.5, farther than 750 light years

If a constellation's displayed stars (= all stars brighter than magnitude ~4.5) include stars at or outside the 750 light year radius circle marking the Sun's location on the NASA image, Galaxies3D will display the magnified patch of the NASA Milky Way Galaxy image, scaled to the grid, in its 3D view of the constellation. That 750 light year radius circle will often appear highly magnified in the view, as in this image of stars in constellation Centaurus:

Centaurus, with bitmap

If a constellation's displayed stars (= all stars brighter than magnitude ~4.5) are all contained within the 750 light year radius circle, Galaxies3D does not display the NASA Milky Way image, as in this image of stars in the constellation Bootes:

Bootes, no bitmap


 

Nearest Stars

In displaying our Sun's "next store" neighboring stars, Galaxies3D paints onto the base galactic plane grid a NASA bitmap of the local interstellar medium:

Local Interstellar Clouds

In this view of all known stars and brown dwarfs up to 16.3 light years from the sun, the color coding of stars by their spectral type helps make it clear that the majority of the stars near the Sun are small, long-lived red main-sequence M-stars. Standing out in this view is the closest star system to the sun, the triple-star system containing α Centauri, a yellow G2 main sequence star just like our Sun, and the blue A1 main sequence star Sirius:

Nearest Stars and Brown Dwarfs

A subset of the above view shows the stars and brown dwarfs within 11 light years of the sun:

Stars and Brown Dwarfs within 11 Light Years of the Sun

 

Bright Stars and Near Stars

Bright Stars Farther Than 750 Light Years
50 Brightest Stars
Brighest Stars Within 1300 Light Years
Brighest Stars Within 270 Light Years
Nearest Stars and Brown Dwarfs
Stars and Brown Dwarfs Within 11 Light Years

 

Bright Stars in the Constellations

All Constellations
Constellations Andromeda to Crater
Constellations Crux to Ophiuchus
Constellations Orion to Vulpecula