The Nearby Stars Project

Spectroscopy in the Local Neighborhood: A High Resolution Survey and Abundance Analysis of Selected Stars

Welcome to the Nearby Stars Project Homepage. This website will enable users to access a high resolution spectroscopic database of stars in the local neighborhood. Click on the links below to find out more.

• Background Information
• Observational Goal
• Instrumentation
• Personnel
• Access to Dwarf Data
• Access to Dwarf Results
• Giants in the Local Region

Background Information & Data Subsets

The Nearby Stars program seeks information on the population of stars in the local neighborhood, i.e., those stars within several hundred parsecs of the Sun. This project will provide vital information on the spectral characteristics of these stars by obtaining high-resolution, high signal-to-noise spectroscopic data on a significant fraction of the stars within 15 parsecs, and by sampling the population within 100 parsecs. The parent sample for this program is those stars in the Hipparcos Parallax Catalog which are within 100 pc of the Sun. This list contains 22010 stars - obviously an impossibility for a high resolution spectroscopic survey. The subsets of interest for this project are the following:

Priority 1:

The stars with distances less than 15 parsecs with absolute magnitudes greater than 10.0 that are north of declination -30.0.

Priority 2:

Samples of stars with characteristics that make them of interest in regard to planets regardless of distance (but which are north of -30 declination) i.e.:

1. Those stars which are known to have planets.
2. Those stars "known" not to have planets.
3. Stars which are metal-rich and hence according to the hypothesis of Gonzalez (1997, 1998) are likely to have planets.
4. A randomly selected control sample of stars of similar spectral type to those of a and b.

(NOTE: For a complete list of stars with planets visit The Encyclopedia of Extrasolar Planets.)

The Hipparcos Parallax Catalog contains 273 stars within 15 parsecs. Applying the selection criteria for Priority Group 1 reduces the list to 156 stars (195 stars total are north of -30 and the absolute magnitude limit eliminates 39 of these). Of the 70 Priority 2 objects 29 are also in Priority Group 1. The total number of Priority 1/2 objects is thus about 200-220 with the precise number depending on how many of the objects in Priority Group 2 also belong to 1.

Priority 3:

A sample of stars within a radius of 100 parsecs drawn from the Hipparcos Parallax Catalog. The volume has been subdivided into 25 parsec cubes centered at the solar position. This yields a volume sampling of 9x9x9 boxes or 729 volume elements of which 389 are within 100 parsecs and north of -30 declination. Approximately 300 of the subelements have Hipparchos stars within them. For each subelement we have selected a giant and a dwarf to observe. For the giants the selection is usually limited but if possible we prefer spectral types G5 to K0. For the dwarfs we select based on absolute magnitude preferring stars in the G0 to G5 range. The absolute magnitudes used are average absolute magnitudes per spectral type and luminosity class determined from the Hipparcos catalog itself.

Observational Goal

To survey at high resolution (R=60000) over a wide spectral range (5000-7000Å) all 200-220 stars in Priority 1/2 and approximately 600 stars from Priority 3 in order to assemble a high quality spectroscopic database which can be used in assessments of:

1. Binarity
2. Spectral peculiarities
3. Spectral variability
4. Metallicity

Detection of items a and b and the determination of metallicity (item d) can often be done using a "single" high quality spectrum whereas c (and orbit determination for a) requires a more extensive temporally spaced database.

Instrumentation

Data for this project are being acquired using the McDonald 2.1m Struve reflector and the Sandiford Echelle Spectrograph, both operated by the McDonald Observatory and the Astronomy Department at the University of Texas at Austin.

Personnel

• Dr. R. Earle Luck, Case Western Reserve University and Dr. Ulrike Heiter, Uppsala Universiet.

Access to Data

Access to this database is provided through http from this site. There are two methods of obtaining data:

• Go to the data main menu for links to individual datasets.
• Or, search for an object by identifier.

Access to Results

The primary results of the work are found in three published papers:

• Heiter, U. & Luck, R.E. “Abundance Analysis of Planetary Host Stars. I. Differential Iron Abundances,” 2003, Astronomical Journal 126, 2015.

• Luck, R.E. & Heiter, U. “Stars within 15 Parsecs: Abundances for a Northern Sample,” 2005, Astronomical Journal, 129, 1063.
  
  
• Luck, R.E. & Heiter, U. “Dwarfs in the Local Region,” 2006, Astronomical Journal, 131, 3069.

A consolidated set of parameters and abundances can be found here.

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