Star formation is often best manifested by bright H II regions.These are regions of hydrogen which have been ionized by ultraviolet photons which are emitted from massive stars (typically stars more than 20 times the mass of the Sun). ... A narrowband filter image centered on this wavelength will then readily reveal these H II regions and hence the current sites of star formation in a galaxy, The luminous blobs that can be seen here are all H II regions . ... NGC 3558 Visual . NGC 3558 Infrared . ...

... According to the most popular cosmological paradigm, the greater part of the galaxy mass is accumulated in the dark matter halo. ... The polar ring galaxies (PRGs) reveal external rings or disks of gas, dust and stars rotating in a plane roughly perpendicular to the disk of the central galaxy. ... The shape of the dark halo in the model was chosen so as to achieve the best fit to the observed rotation of both galaxies themselves and their polar rings. ... The SPRC-7 galaxy. ...

... The MMT optical spectra of SBS 0335-052W were obtained on 1996 January 19 with the Red Channel of the MMT Spectrograph. ... The linear scale is 1 = 263 pc at the distance to SBS 0335-052W of 54.1 Mpc. ... In Table 1, the observed line intensities and intensities corrected for interstellar extinction for SBS 0335-052W are shown along with extinction coefficient C (H ), observed flux of the H emission line, the equivalent width EW (H ) and equivalent width of absorption Balmer hydrogen lines EW (abs)....

The HST images of GRB 990123. HST has observed this field in the 50CCD (open) filter on the 8 February 1999, 23 March 1999, and the 7 February 2000, or 16, 59 and 380 days after outburst. ... On the left in the above image is the February 1999 image of GRB 990123, on the right the difference between that image and the February 2000 image. ... On the left in the above image is the March 1999 image of GRB 990123, on the right the difference between that image and the February 2000 image. ... 1999). ...

... Here some data observed on the 6m telescope with IFP installed in the OLD focal reducer are presented. ... Mkn 3: velocity field . ... NGC 5252: [OIII] image . ... NGC 5252 was observed 23 Feb. 1998 in the [OIII]5007 emission line with CCD TK1024 as detector. ... We observed the ionized gas velocity fields of the spiral galaxies with two purpose. ... Restored velocity field of NGC 157 in the reference frame rotating with the pattern speed overlaid on the Ha image of the galaxy . ... NGC 4100 . ...

... The stars examined here were primarily culled from two lists of X--ray sources in Orion. ... The second region is two degrees in extent east--west and ten degrees north--south with Orionis being near the northern edge. ... In the end, two main regions were chosen for monitoring: stars near Orionis and stars northwest of the belt of Orion. ... The PSPC identified 22 sources within 15 of Orionis in addition to the sources listed in Table 1 , giving a total of 85 X--ray sources in the Orionis region. ...

... Science . ... Science Users Information > Science Activities > PhD Thesis Topics offered by ESO Faculty Members > Thesis Topic: Probing the central regions of galaxies . ... Observing Facilities . ... Data Handling and Products . ... Science Data Products Forum . ... Science Archive Facility . ... ESO Data . ... The advent of near IR spectroscopy in conjunction with adaptive optics on large telescopes allows to observe the central regions of galaxies at unprecedented spatial resolutions. ...

... For immediate release . The VLT Infrared Spectrometer And Array Camera (ISAAC) [1] was installed at the first 8.2-m VLT Unit Telescope (UT1) on November 14, 1998, cf. ESO PR Photos 42a-h/98 . ... The first focus tests on stars yielded images of excellent sharpness, around 0.45 arcsec full-width-half-maximum (FWHM). ... This Press Release is accompanied by several images and spectra which illustrate some of the exceptional new astronomical capabilities offered by this instrument. ...

NATIONAL ASTRONOMY AND IONOSPHERE CENTER . ... Astronomy . ... Visitor Center . ... Optical . Lidar . At Arecibo we have a variety of optical instruments that we use to study terrestrial airglow emissions. ... This equipment is located in our Optical Laboratory, which is on site about 1000 feet from the center of the incoherent scatter radar. ... The various observational modes that are available are described in supplementary documentation for the Arecibo Observatory Optical Laboratories. ...

... Our Sun is part of a huge wheel-shaped collection of stars. ... Astronomers have long suspected it was a very massive black hole, and that every galaxy had such a central mass, created early in the history of the universe. ... However, unless that object happens to be headed directly at the black hole (a relatively small target) it will just swing around and fly away again, like a comet making a pass at the Sun. The velocity acquired in falling towards the black hole also helps it escape. ...