Optical and infrared colors of stars observed by the Two Micron All Sky Survey and the Sloan Digital Sky Survey

Kristian Finlator, Željko Ivezić, Xiaohui Fan, Michael A. Strauss, Gillian R. Knapp, Robert H. Lupton, James E. Gunn, Constance M. Rockosi, John E. Anderson, István Csabai, Gregory S. Hennessy, Robert B. Hindsley, Timothy A. McKay, Robert C. Nichol, Donald P. Schneider, J. Allyn Smith, Donald G. York

Research output: Contribution to journalArticle

101 Citations (Scopus)

Abstract

We discuss optical and infrared photometric properties of stars matched in the Two Micron All Sky Survey (2MASS) and the Sloan Digital Sky Survey (SDSS) commissioning data for ∼50 deg2 of sky along the celestial equator centered at l = 150°, b = -60°. About 98% (∼63,000) of objects listed in the 2MASS Point Source Catalog in the analyzed area are matched within 2″ to an SDSS source. The matched sources represent 8% of the ∼800,000 SDSS sources in this area. They are predominantly red sources, as expected, and 15% of them are resolved in SDSS imaging data although they are detected as point sources in 2MASS data. The distribution of positional discrepancies for the matched sources and the astrometric statistics for the multiply observed SDSS sources imply that the astrometric accuracy of both surveys is about 0″.1 per coordinate (rms). For about 14,000 stars with the smallest photometric errors (≲10%) in both surveys, we present optical and infrared color-magnitude and color-color diagrams. We use optical (SDSS) colors to identify the stellar spectral sequence and show that stars of different spectral types can have similar infrared colors, thus making the classification of stars based on only 2MASS data very difficult. However, a broad separation into "early" and "late" spectral types (relative to type K0) is possible with a reliability of ∼95% even with 2MASS colors alone. The distributions of matched sources in color-magnitude and color-color diagrams are compared with the predictions of a stellar population synthesis code. We find that the models are in fair overall agreement with the data. In particular, the total number counts agree to better than 10%, and the morphologies of the color-magnitude and color-color diagrams appear similar. The most significant discrepancies are found for the number ratio of "early" to "late" type stars (by about a factor of 2) and in the colors of M stars (up to 0.2 mag). The first disagreement indicates that some parameters of the standard Galactic structure model and/or initial mass function can be improved, and the second disagreement emphasizes known difficulties with the modeling of stellar atmospheres for cool stars.

Original languageEnglish (US)
Pages (from-to)2615-2626
Number of pages12
JournalAstronomical Journal
Volume120
Issue number5
StatePublished - Nov 2000
Externally publishedYes

Fingerprint

color
stars
color-color diagram
point sources
galactic structure
cool stars
stellar atmospheres
M stars
diagram
equators
point source
catalogs
sky
statistics
synthesis
predictions
atmosphere
prediction
modeling

Keywords

  • Galaxy: stellar content

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Finlator, K., Ivezić, Ž., Fan, X., Strauss, M. A., Knapp, G. R., Lupton, R. H., ... York, D. G. (2000). Optical and infrared colors of stars observed by the Two Micron All Sky Survey and the Sloan Digital Sky Survey. Astronomical Journal, 120(5), 2615-2626.

Optical and infrared colors of stars observed by the Two Micron All Sky Survey and the Sloan Digital Sky Survey. / Finlator, Kristian; Ivezić, Željko; Fan, Xiaohui; Strauss, Michael A.; Knapp, Gillian R.; Lupton, Robert H.; Gunn, James E.; Rockosi, Constance M.; Anderson, John E.; Csabai, István; Hennessy, Gregory S.; Hindsley, Robert B.; McKay, Timothy A.; Nichol, Robert C.; Schneider, Donald P.; Smith, J. Allyn; York, Donald G.

In: Astronomical Journal, Vol. 120, No. 5, 11.2000, p. 2615-2626.

Research output: Contribution to journalArticle

Finlator, K, Ivezić, Ž, Fan, X, Strauss, MA, Knapp, GR, Lupton, RH, Gunn, JE, Rockosi, CM, Anderson, JE, Csabai, I, Hennessy, GS, Hindsley, RB, McKay, TA, Nichol, RC, Schneider, DP, Smith, JA & York, DG 2000, 'Optical and infrared colors of stars observed by the Two Micron All Sky Survey and the Sloan Digital Sky Survey', Astronomical Journal, vol. 120, no. 5, pp. 2615-2626.
Finlator K, Ivezić Ž, Fan X, Strauss MA, Knapp GR, Lupton RH et al. Optical and infrared colors of stars observed by the Two Micron All Sky Survey and the Sloan Digital Sky Survey. Astronomical Journal. 2000 Nov;120(5):2615-2626.
Finlator, Kristian ; Ivezić, Željko ; Fan, Xiaohui ; Strauss, Michael A. ; Knapp, Gillian R. ; Lupton, Robert H. ; Gunn, James E. ; Rockosi, Constance M. ; Anderson, John E. ; Csabai, István ; Hennessy, Gregory S. ; Hindsley, Robert B. ; McKay, Timothy A. ; Nichol, Robert C. ; Schneider, Donald P. ; Smith, J. Allyn ; York, Donald G. / Optical and infrared colors of stars observed by the Two Micron All Sky Survey and the Sloan Digital Sky Survey. In: Astronomical Journal. 2000 ; Vol. 120, No. 5. pp. 2615-2626.
@article{7512a298d7994fd8a959f7945c5d34f1,
title = "Optical and infrared colors of stars observed by the Two Micron All Sky Survey and the Sloan Digital Sky Survey",
abstract = "We discuss optical and infrared photometric properties of stars matched in the Two Micron All Sky Survey (2MASS) and the Sloan Digital Sky Survey (SDSS) commissioning data for ∼50 deg2 of sky along the celestial equator centered at l = 150°, b = -60°. About 98{\%} (∼63,000) of objects listed in the 2MASS Point Source Catalog in the analyzed area are matched within 2″ to an SDSS source. The matched sources represent 8{\%} of the ∼800,000 SDSS sources in this area. They are predominantly red sources, as expected, and 15{\%} of them are resolved in SDSS imaging data although they are detected as point sources in 2MASS data. The distribution of positional discrepancies for the matched sources and the astrometric statistics for the multiply observed SDSS sources imply that the astrometric accuracy of both surveys is about 0″.1 per coordinate (rms). For about 14,000 stars with the smallest photometric errors (≲10{\%}) in both surveys, we present optical and infrared color-magnitude and color-color diagrams. We use optical (SDSS) colors to identify the stellar spectral sequence and show that stars of different spectral types can have similar infrared colors, thus making the classification of stars based on only 2MASS data very difficult. However, a broad separation into {"}early{"} and {"}late{"} spectral types (relative to type K0) is possible with a reliability of ∼95{\%} even with 2MASS colors alone. The distributions of matched sources in color-magnitude and color-color diagrams are compared with the predictions of a stellar population synthesis code. We find that the models are in fair overall agreement with the data. In particular, the total number counts agree to better than 10{\%}, and the morphologies of the color-magnitude and color-color diagrams appear similar. The most significant discrepancies are found for the number ratio of {"}early{"} to {"}late{"} type stars (by about a factor of 2) and in the colors of M stars (up to 0.2 mag). The first disagreement indicates that some parameters of the standard Galactic structure model and/or initial mass function can be improved, and the second disagreement emphasizes known difficulties with the modeling of stellar atmospheres for cool stars.",
keywords = "Galaxy: stellar content",
author = "Kristian Finlator and Željko Ivezić and Xiaohui Fan and Strauss, {Michael A.} and Knapp, {Gillian R.} and Lupton, {Robert H.} and Gunn, {James E.} and Rockosi, {Constance M.} and Anderson, {John E.} and Istv{\'a}n Csabai and Hennessy, {Gregory S.} and Hindsley, {Robert B.} and McKay, {Timothy A.} and Nichol, {Robert C.} and Schneider, {Donald P.} and Smith, {J. Allyn} and York, {Donald G.}",
year = "2000",
month = "11",
language = "English (US)",
volume = "120",
pages = "2615--2626",
journal = "Astronomical Journal",
issn = "0004-6256",
publisher = "IOP Publishing Ltd.",
number = "5",

}

TY - JOUR

T1 - Optical and infrared colors of stars observed by the Two Micron All Sky Survey and the Sloan Digital Sky Survey

AU - Finlator, Kristian

AU - Ivezić, Željko

AU - Fan, Xiaohui

AU - Strauss, Michael A.

AU - Knapp, Gillian R.

AU - Lupton, Robert H.

AU - Gunn, James E.

AU - Rockosi, Constance M.

AU - Anderson, John E.

AU - Csabai, István

AU - Hennessy, Gregory S.

AU - Hindsley, Robert B.

AU - McKay, Timothy A.

AU - Nichol, Robert C.

AU - Schneider, Donald P.

AU - Smith, J. Allyn

AU - York, Donald G.

PY - 2000/11

Y1 - 2000/11

N2 - We discuss optical and infrared photometric properties of stars matched in the Two Micron All Sky Survey (2MASS) and the Sloan Digital Sky Survey (SDSS) commissioning data for ∼50 deg2 of sky along the celestial equator centered at l = 150°, b = -60°. About 98% (∼63,000) of objects listed in the 2MASS Point Source Catalog in the analyzed area are matched within 2″ to an SDSS source. The matched sources represent 8% of the ∼800,000 SDSS sources in this area. They are predominantly red sources, as expected, and 15% of them are resolved in SDSS imaging data although they are detected as point sources in 2MASS data. The distribution of positional discrepancies for the matched sources and the astrometric statistics for the multiply observed SDSS sources imply that the astrometric accuracy of both surveys is about 0″.1 per coordinate (rms). For about 14,000 stars with the smallest photometric errors (≲10%) in both surveys, we present optical and infrared color-magnitude and color-color diagrams. We use optical (SDSS) colors to identify the stellar spectral sequence and show that stars of different spectral types can have similar infrared colors, thus making the classification of stars based on only 2MASS data very difficult. However, a broad separation into "early" and "late" spectral types (relative to type K0) is possible with a reliability of ∼95% even with 2MASS colors alone. The distributions of matched sources in color-magnitude and color-color diagrams are compared with the predictions of a stellar population synthesis code. We find that the models are in fair overall agreement with the data. In particular, the total number counts agree to better than 10%, and the morphologies of the color-magnitude and color-color diagrams appear similar. The most significant discrepancies are found for the number ratio of "early" to "late" type stars (by about a factor of 2) and in the colors of M stars (up to 0.2 mag). The first disagreement indicates that some parameters of the standard Galactic structure model and/or initial mass function can be improved, and the second disagreement emphasizes known difficulties with the modeling of stellar atmospheres for cool stars.

AB - We discuss optical and infrared photometric properties of stars matched in the Two Micron All Sky Survey (2MASS) and the Sloan Digital Sky Survey (SDSS) commissioning data for ∼50 deg2 of sky along the celestial equator centered at l = 150°, b = -60°. About 98% (∼63,000) of objects listed in the 2MASS Point Source Catalog in the analyzed area are matched within 2″ to an SDSS source. The matched sources represent 8% of the ∼800,000 SDSS sources in this area. They are predominantly red sources, as expected, and 15% of them are resolved in SDSS imaging data although they are detected as point sources in 2MASS data. The distribution of positional discrepancies for the matched sources and the astrometric statistics for the multiply observed SDSS sources imply that the astrometric accuracy of both surveys is about 0″.1 per coordinate (rms). For about 14,000 stars with the smallest photometric errors (≲10%) in both surveys, we present optical and infrared color-magnitude and color-color diagrams. We use optical (SDSS) colors to identify the stellar spectral sequence and show that stars of different spectral types can have similar infrared colors, thus making the classification of stars based on only 2MASS data very difficult. However, a broad separation into "early" and "late" spectral types (relative to type K0) is possible with a reliability of ∼95% even with 2MASS colors alone. The distributions of matched sources in color-magnitude and color-color diagrams are compared with the predictions of a stellar population synthesis code. We find that the models are in fair overall agreement with the data. In particular, the total number counts agree to better than 10%, and the morphologies of the color-magnitude and color-color diagrams appear similar. The most significant discrepancies are found for the number ratio of "early" to "late" type stars (by about a factor of 2) and in the colors of M stars (up to 0.2 mag). The first disagreement indicates that some parameters of the standard Galactic structure model and/or initial mass function can be improved, and the second disagreement emphasizes known difficulties with the modeling of stellar atmospheres for cool stars.

KW - Galaxy: stellar content

UR - http://www.scopus.com/inward/record.url?scp=17544393966&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=17544393966&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:17544393966

VL - 120

SP - 2615

EP - 2626

JO - Astronomical Journal

JF - Astronomical Journal

SN - 0004-6256

IS - 5

ER -