New probable dwarf galaxies in northern groups of the Local Supercluster     

I. D. Karachentsev  V. E. Karachentseva  W. K. Huchtmeier 《Astronomy Letters》2007,33(8):512-519

We have searched for nearby dwarf galaxies in 27 northern groups with characteristic distances 8–15 Mpc based on the Second Palomar Sky Survey prints. In a total area of about 2000 square degrees, we have found 90 low-surface-brightness objects, more than 60% of which are absent from known catalogs and lists. We have classified most of these objects (～80%) as irregular dwarf systems. The first 21-cm line observations of the new objects with the 100-m Effelsberg radio telescope showed that the typical linear diameters (1–2 kpc), internal motions (～30 km s^?1), and hydrogen masses (～2 × 10⁷ M _⊙) of the new galaxies correspond to those expected for the dwarf population of nearby groups.  相似文献   

Distances and peculiar velocities of spiral galaxies in the 2MFGC and SFI++ samples     

Yu. N. Kudrya  V. E. Karachentseva  I. D. Karachentsev  S. N. Mitronova  W. K. Huchtmeier 《Astrophysics》2009,52(3):335-349

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Bulk motions of spiral galaxies in the z = 0.03 volume     

Yu. N. Kudrya  V. E. Karachentseva  I. D. Karachentsev  S. N. Mitronova  W. K. Huchtmeier 《Astronomy Letters》2006,32(2):73-83

We analyze the peculiar velocity field for 2400 flat spiral galaxies selected from an infrared sky survey (2MFGC). The distances to the galaxies have been determined from the Tully-Fisher relation in the photometric J band with a dispersion of 0^m.45. The bulk motion of this sample relative to the cosmic microwave background (3K) frame has an amplitude of 199 ± 37 km s^?1 in the direction l = 290° ± 11°, b = +1° ± 9°. The amplitude of the dipole motion tends to decrease with distance in accordance with the expected convergence of bulk flows in the 3K frame. We believe that external massive attractors similar to the Shapley cluster concentration are responsible for ～60% of the local flow velocity in the z = 0.03 volume.  相似文献   

H I observations of flat galaxies     

S. N. Mitronova  W. K. Huchtmeier  I. D. Karachentsev  V. E. Karachentseva  Yu. N. Kudrya 《Astronomy Letters》2005,31(8):501-514

We present the HI observations of 94 flat spiral galaxies from RFGC (Revised Flat Galaxy Catalog) and 14 galaxies from 2MFGC (the 2MASS selected Flat Galaxy Catalog) performed with the 100-m radio telescope in Effelsberg (Germany). HI fluxes, heliocentric radial velocities, and HI line widths are given for 65 detected galaxies. We present a mosaic of HI profiles. We calculated some of the global parameters of the galaxies and analyzed the linear correlations between them. The ratios of the total (indicative) masses of the galaxies to their luminosities lie within the range 0.4–8.2 with a mean of 3.8 (M_⊙/L_⊙), and the mean mass fraction of neutral hydrogen is 13%. Upper limits are given for the radio fluxes from 43 undetected galaxies.  相似文献   

K-band Radio Observations of Comet Hale-Bopp: Detections of Ammonia and (Possibly) Water     

Bird  M. K.  Janardhan  P.  Wilson  T. L.  Huchtmeier  W. K.  Gensheimer  P.  Lemme  C. 《Earth, Moon, and Planets》1997,78(1-3):21-28

K-band radio observations of comet Hale-Bopp (C/1995 O1) were conducted in March/April 1997 at the 100-m Telescope of the Max-Planck-Institut für Radioastronomie. Emission was firmly detected from the five lowest metastable (J = K)inversion transitions of ammonia. Assuming a thermal distribution for the metastable states of NH₃, we derive a rotational temperature of 104 ± 30 K and an ammonia production rate at perihelion of6.6 ± 1.3 × 10²⁸ s^-1.The updated ammonia-to-water abundance ratio is found to be of the order of 1.0%. We also report a marginal detection of the 6₁₆–5₂₃transition line of water at λ = 1.35 cm. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献