The Extinction and Distance of Maffei 1

Abstract

We have obtained low-and high-resolution spectra of the core of the highly reddened elliptical galaxy Maffei 1. From these data, we have obtained the first measurement of the Mg 2 index and have measured the velocity dispersion and radial velocity with improved accuracy. To evaluate the extinction, a correlation between the Mg 2 index and effective VÀI color has been established for elliptical galaxies. Using a new method for correcting for effective wavelength shifts, the VÀI color excess reveals that the optical depth of Galactic dust at 1 lm is 1:69 AE 0:07. Thus, A V ¼ 4:67 AE 0:19 mag, which is lower by 0.4 mag than previously thought. To establish the distance, the fundamental plane for elliptical galaxies has been constructed in I. The velocity dispersion of Maffei 1, measured to be 186:8 AE 7:4 km s À1 , in combination with modern widefield photometry in I, leads to a distance of 2:92 AE 0:37 Mpc. The D n -relation, which is independently calibrated, gives 3:08 AE 0:85 and 3:23 AE 0:67 Mpc from photometry in B and K 0 , respectively. The weighted mean of the three estimates is 3:01 AE 0:30 Mpc, which is lower than distances judged with reference to M32 and the bulge of M31 from the brightest stars seen at K 0 . Since the luminosity of asymptotic giant branch stars at K 0 is strongly dependent on age, the lower distance suggests that the last epoch of star formation in Maffei 1 occurred farther in the past than in these other systems. The distance and luminosity make Maffei 1 the nearest giant elliptical galaxy. In the absence of extinction, the galaxy would be among the brightest in the sky and would have an apparent size 2 3 that of the full Moon. The radial velocity of Maffei 1 is +66:4 AE 5:0 km s À1 , significantly higher than the accepted value of À10 km s À1 . The Hubble distance corresponding to the mean velocity of Maffei 1, Maffei 2, and IC 342 is 3.5 Mpc. Thus, it is unlikely that Maffei 1 has had any influence on Local Group dynamics.

Search for high-energyγ-ray emission from galaxies of the Local Group withFermi/LAT

“…(1) Abdo et al (2010a); (2) Dame (1993); (3) Galleti et al (2004); (16) Gratier et al (2010); (17) Karachentsev et al (2003a); (18) Fingerhut et al (2003); (19) Karachentsev et al (2004); (20) Ando et al (2005); (21) Rots (1979); (22) Karachentsev et al (2002a); (23) Karachentsev et al (2002b); (24) Lenc & Tingay (2009); (25) Weiß et al (2008); (26) Lenain et al (2010); (27) Karachentsev & Kaisin (2007); (28) Matonick & Fesen (1997); (29) Gurovich et al (2010); (30) Karachentsev et al (2003b); (31) (2003); (36) Sage et al (1990).…”

Distances to nearby galaxies around IC 342

“…The distance to the brightest group member, IC 342, was determined by Saha et al (2002) from the P − L relation for Cepheids. Fingerhut et al (2003) estimated the distance to the elliptical galaxy Maffei 1 using its central velocity dispersion and I band photometry. In the present paper we determine new distances to five more galaxies in the vicinity of IC 342 based on their tip of red giant branch (TRGB) derived from the Hubble Space Telescope (HST) images.…”

Distance to the galaxy IC 342

“…The spatial location of the massive elliptical galaxy Maffei 1 is of particular importance in determining all characteristics of the IC 342/Maffei group. Whereas Maffei 1 was initially included even in the Local Group (Spinrad 1971), its distance was subsequently increased to 2 Mpc (Buta & McCall 1983) and, in the last decade, its value varies between 3 and 4.5 Mpc (Luppino & Tonry 1993;Davidge & van den Bergh 2001, 2005Fingerhut et al 2003). The most recent measurements based on the photometry of the globular clusters found give a distance of 4.1 Mpc (Davidge & van den Bergh 2005), which makes the two galaxies (IC 342 and Maffei 1) the unquestionable center of the group with a spatial separation between them of 0.8 Mpc.…”

“…Despite intensive studies of individual galaxies that are probable members of this group (McCall 1989;Krismer et al 1995;Buta & McCall 1999;Davidge & van den Bergh 2001, 2005Saha et al 2002;Karachentsev et al 2003;Fingerhut et al 2003), the question about the population of the group and the spatial positions of its individual galaxies remains unsolved. High extinction (light absorption and scattering) in gas-dust clouds of our Galaxy prevents the spatial parameters of the group from being determined, because all of the probable group members are located in the Milky Way zone.…”