2MASS wide field extinction maps

III. The Taurus, Perseus, and California cloud complexes

¹ European Southern Observatory, Karl-Schwarzschild-Straße 2, 85748 Garching bei München, Germany e-mail: mlombard@eso.org
² University of Milan, Department of Physics, via Celoria 16, 20133 Milan, Italy (on leave)
³ Harvard-Smithsonian Center for Astrophysics, Mail Stop 72, 60 Garden Street, Cambridge, MA 02138, UK
⁴ Calar Alto Observatory – Centro Astronómico Hispano Alemán, C/Jesús Durbán Remón 2-2, 04004 Almeria, Spain

Received: 9 June 2009
Accepted: 20 October 2009

Abstract

We present a near-infrared extinction map of a large region in the sky (~ 3500 deg²) in the general directions of Taurus, Perseus, and Aries. The map has been obtained using robust and optimal methods to map dust column density at near-infrared wavelengths (Nicer, described in Lombardi & Alves 2001, A&A, 377, 1023 and Nicest, described in Lombardi 2009, A&A, 493, 735) toward ~23 million stars from the Two Micron All Sky Survey (2MASS) point source catalog. We measure extinction as low as A_K = 0.04 mag with a 1-σ significance, and a resolution of 2.5 arcmin in our map. A 250 deg² section of our map encompasses the Taurus, Perseus, and California molecular cloud complexes. We determine the distances of the clouds by comparing the observed density of foreground stars with the prediction of galactic models, and we obtain results that are in excellent agreement with recent VLBI parallax measurements. We characterize the large-scale structure of the map and find a ~ 25° × 15° region close to the galactic plane (l ~ 135°, b ~ -14°) with small extinction (A_K < 0.04 mag); we name this region the Perseus-Andromeda hole. We find that over the region that encompasses the Taurus, Perseus, and California clouds the column density measurements below A_K < 0.2 mag are perfectly described by a log-normal distribution, and that a significant deviation is observed at larger extinction values. If turbulence models are invoked to justify the log-normal distribution, the observed departure could be interpreted as the result of the effect of gravity that acts on the cores of the clouds. Finally, we investigate the cloud structure function, and show that significant deviations from the results predicted by turbulent models are observed in at least one cloud.