Extinction Ratios in the Inner Galaxy as Revealed by the VVV Survey

Javier Alonso-García, Dante Minniti, Márcio Catelan, Rodrigo Contreras Ramos, Oscar A. Gonzalez, Maren Hempel, Philip W. Lucas, Roberto K. Saito, Elena Valenti, Manuela Zoccali

Research output: Contribution to journalReview articlepeer-review

59 Citations (Scopus)


Interstellar extinction toward the Galactic Center (GC) is large and significantly differential. Its reddening and dimming effects in red clump (RC) stars in the Galactic Bulge can be exploited to better constrain the extinction law toward the innermost Galaxy. By virtue of a deep and complete catalog of more than 30 million objects at |l| ≤ 2°.7 and |b| ≤ 1°.55 obtained from VVV survey observations, we apply the RC method to infer the selective-to-total extinction ratios in the Z, Y, J, H, and Ks broadband near-infrared filters. The measured values are smaller than previously reported, and are not constant, with mean values of, e.g., AKS /E(J - Ks) = 0.428 ± 0.005 ± 0.04 and AKS/ E(H Ks) = 1.104 ± 0.022 ± 0.2. We also obtain a ratio AZ:AY:AJ:AH:AKS of 7.74:5.38:3.30:1.88:1.0, implying extinction toward the GC to follow a distribution as a function of wavelength steeper than previously reported, consistent with a power law Aλ ∝ λ -2.47 in the near-infrared.

Original languageEnglish
Article numberL13
JournalAstrophysical Journal Letters
Issue number1
Publication statusPublished - 1 Nov 2017


  • dust, extinction
  • Galaxy: center
  • infrared: ISM

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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