Selected Star Systems Within 40 Parsecs (130 Light Years)
DEEP FLY 2008

This diagram is a visual summary of the Solar neighborhood, seen from the perspective of an observer in the north celestial hemisphere. Within 40 parsecs of the Sun, it represents:

• A selection of the brightest stars, including red giants and main-sequence stars of spectral classes B and A
• A dozen A stars with debris disks, including two systems (Fomalhaut, HR 8799) with directly imaged planets; many other nearby debris disk systems are not shown
• Fourteen F and G stars that host planetary systems, with a focus on systems containing two or more planets and systems with the potential to host Earthlike moons

Because this diagram focuses on exoplanetary systems, debris disks, and bright "landmark" stars (the ones most visible from the greatest distances), it is misleading. We should imagine this region peppered with dim red M dwarfs, along with a few thousand of the yellowish and orange stars that makethe best candidates for planetary hosts. Such detail, unfortunately, is impossible in a small image.

About 3600 dwarf and giant stars of spectral types B through K are currently orbiting the Galactic Center within 40 parsecs of the Sun (Gray et al. 2006). Assuming that M dwarfs represent 70% of all stars in the Local Bubble, this 40-parsec sphere contains about 12,000 stars altogether.

As of late 2008, just over 100 exoplanetary systems have been announced in the same volume of space. Among them are 9 systems that contain 3 or more planets, 11 systems that contain 2 planets, and more than 80 systems that contain only one detected planet. Many more systems undoubtedly await discovery. Thirty-eight exosystems are currently known within 20 parsecs, for a distribution of about 1 per 1000 cubic parsecs. If the same frequency obtains within 40 parsecs, at least 150 more planet-bearing stars may be present in this space.

Within the same volume, infrared searches have confirmed the presence of debris corresponding to the Solar System's Asteroid and Kuiper Belts around at least 63 stars. This total represents 19 A-type stars, 41 Sun-like stars, and 3 M dwarfs (Su et al. 2006, Hillenbrand et al. 2008, Trilling et al. 2008, Shankland et al. 2008). Among the Sun-like stars, 11 systems with debris also harbor detected planets (see Sun-like Stars with Debris).

Because debris is often interpreted as a "signpost of planetary system formation" (Trilling et al. 2007), these detections may represent the tip of an iceberg. It may turn out that, regardless of spectral type, most stars with debris also harbor one or more planets.

Absent from this region of space are the extreme objects that typically fascinate astronomers – pulsars, quasars, black holes, neutron stars, dark matter filaments. The closest known neutron star is about 200 light years away, while the closest known black hole is 1600 light years away. If we seek prodigies nearby, we must be satisfied by dazzling systems like Algol, a B-type star with an enormous red giant companion; clusters of bright sibling stars like the Ursa Major Association; and Super Jupiters like the outer companion of HD 168443.