A spectroscopic study of the ancient milky way: f- and g-type stars in the third data release of the sloan digital sky survey

PDF Version Also Available for Download.

Description

We perform an analysis of spectra and photometry for 22,770 stars included in the third data release (DR3) of the Sloan Digital Sky Survey (SDSS). We measure radial velocities and, based on a model-atmosphere analysis, derive estimates of the atmospheric parameters (effective temperature, surface gravity, and [Fe/H]) for each star. Stellar evolution models are then used to estimate distances. We thoroughly check our analysis procedures using three recently published spectroscopic libraries of nearby stars, and compare our results with those obtained from alternative approaches. The SDSS sample covers a range in stellar brightness of 14 < V < 22, primarily ... continued below

Physical Description

18 pages

Creation Information

Allende Prieto, Carlos; /Texas U., McDonald Observ. /Texas U., Astron. Dept.; Beers, T.C.; U., /Michigan State; Wilhelm, R.; Tech., /Texas et al. September 1, 2005.

Context

This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. More information about this article can be viewed below.

Who

People and organizations associated with either the creation of this article or its content.

Provided By

UNT Libraries Government Documents Department

Serving as both a federal and a state depository library, the UNT Libraries Government Documents Department maintains millions of items in a variety of formats. The department is a member of the FDLP Content Partnerships Program and an Affiliated Archive of the National Archives.

Contact Us

What

Descriptive information to help identify this article. Follow the links below to find similar items on the Digital Library.

Description

We perform an analysis of spectra and photometry for 22,770 stars included in the third data release (DR3) of the Sloan Digital Sky Survey (SDSS). We measure radial velocities and, based on a model-atmosphere analysis, derive estimates of the atmospheric parameters (effective temperature, surface gravity, and [Fe/H]) for each star. Stellar evolution models are then used to estimate distances. We thoroughly check our analysis procedures using three recently published spectroscopic libraries of nearby stars, and compare our results with those obtained from alternative approaches. The SDSS sample covers a range in stellar brightness of 14 < V < 22, primarily at intermediate galactic latitudes, and comprises large numbers of F- and G-type stars from the thick-disk and halo populations (up to 100 kpc from the galactic plane), therefore including some of the oldest stars in the Milky Way. In agreement with previous results from the literature, we find that halo stars exhibit a broad range of iron abundances, with a peak at [Fe/H] {approx_equal} -1.4. This population exhibits essentially no galactic rotation. Thick-disk G-dwarf stars at distances from the galactic plane in the range 1 < |z| < 3 kpc show a much more compact metallicity distribution, with a maximum at [Fe/H] {approx_equal} -0.7, and a median galactic rotation velocity at that metallicity of 157 {+-} 4 km s{sup -1} (a lag relative to the thin disk of 63 km s{sup -1}). SDSS DR3 includes spectra of many F-type dwarfs and subgiants between 1 and 3 kpc from the plane with galactic rotation velocities consistent with halo membership. A comparison of color indices and metal abundances with isochrones indicates that no significant star formation has taken place in the halo in the last {approx} 11 Gyr, but there are thick-disk stars which are at least 2 Gyr younger. We find the metallicities of thick-disk stars to be nearly independent of galactocentric distance between 5 and 14 kpc from the galactic center, in contrast with the marked gradients found in the literature for the thin disk. No vertical metallicity gradient is apparent for the thick disk, but we detect a gradient in its rotational velocity of -16 {+-} 4 km s{sup -1} kpc{sup -1} between 1 and 3 kpc from the plane. We estimate that among the stars in our sample there are over 2000 with an iron abundance [Fe/H] < -2, and over 150 stars with an iron abundance [Fe/H] < -3.

Physical Description

18 pages

Source

  • Journal Name: Astrophys.J.636:804-820,2006

Language

Item Type

Identifier

Unique identifying numbers for this article in the Digital Library or other systems.

  • Report No.: FERMILAB-PUB-05-443-CD
  • Grant Number: AC02-76CH03000
  • DOI: 10.1086/498131 | External Link
  • Office of Scientific & Technical Information Report Number: 891091
  • Archival Resource Key: ark:/67531/metadc873185

Collections

This article is part of the following collection of related materials.

Office of Scientific & Technical Information Technical Reports

What responsibilities do I have when using this article?

When

Dates and time periods associated with this article.

Creation Date

  • September 1, 2005

Added to The UNT Digital Library

  • Sept. 21, 2016, 2:29 a.m.

Description Last Updated

  • Dec. 2, 2016, 12:29 p.m.

Usage Statistics

When was this article last used?

Congratulations! It looks like you are the first person to view this item online.

Interact With This Article

Here are some suggestions for what to do next.

Start Reading

PDF Version Also Available for Download.

Citations, Rights, Re-Use

Allende Prieto, Carlos; /Texas U., McDonald Observ. /Texas U., Astron. Dept.; Beers, T.C.; U., /Michigan State; Wilhelm, R.; Tech., /Texas et al. A spectroscopic study of the ancient milky way: f- and g-type stars in the third data release of the sloan digital sky survey, article, September 1, 2005; Batavia, Illinois. (digital.library.unt.edu/ark:/67531/metadc873185/: accessed August 18, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.