Early-type galaxies as seen by SDSS and MegaCam (image release)
Each panel displays true color images obtained with MegaCam on the CFHT (Right: composite of g’+r’+i’ or g’+r’ observations), and for reference with the Sloan Digital Sky Survey (Top left: SDSS/DR8 image queried from the navigation tool Aladin @ CDS). Their field of view corresponds to 40 times the effective radius of the galaxy. A grey- scale g’-band version of the MegaCam image, with a field of view of about 57×57 arcmin, is displayed to the bottom right. To better identify the various objects in the field – galaxies, but also foreground stars and extended Galactic cirrus –, the composite g+r or g+r+i image has been superimposed in overburden areas. The white square delineates the area covered by the other sub-panels.
Identification of old tidal dwarfs near early-type galaxies from deep imaging and H I observations
It has recently been proposed that the dwarf spheroidal galaxies located in the Local Group discs of satellites (DoSs) may be tidal dwarf galaxies (TDGs) born in a major merger at least 5 Gyr ago. Whether TDGs can live that long is still poorly constrained by observations. As part of deep optical and H I surveys with the Canada-France-Hawaii Telescope (CFHT) MegaCam camera and Westerbork Synthesis Radio Telescope made within the ATLAS3D project, and follow-up spectroscopic observations with the Gemini-North telescope, we have discovered old TDG candidates around several early-type galaxies.
Continue reading “Identification of old tidal dwarfs near early-type galaxies from deep imaging and H I observations”NGC 1266 as a Local Candidate for Rapid Cessation of Star Formation
We present new Spectrographic Areal Unit for Research on Optical Nebulae (SAURON) integral-field spectroscopy and Swift Ultraviolet Optical Telescope (UVOT) observations of molecular outflow host galaxy NGC 1266 that indicate NGC 1266 has experienced a rapid cessation of star formation.
Continue reading “NGC 1266 as a Local Candidate for Rapid Cessation of Star Formation”Discovery of a giant HI tail in the galaxy group HCG 44
We report the discovery of a giant HI tail in the intragroup medium of HCG 44 as part of the ATLAS3D survey. The tail is ˜ 300 kpc long in projection and contains ˜ 5 × 108 M⊙ of HI. We detect no diffuse stellar light at the location of the tail down to ˜ 28.5 mag arcsec– 2 in g band.
Continue reading “Discovery of a giant HI tail in the galaxy group HCG 44”Protected: MATLAS large program proposal
Elliptical galaxies much younger than previously thought? (CFHT press release)
The standard model for elliptical galaxies formation is challenged by a new result uncovered by an international team of astronomers from the Atlas3D collaboration. Team members from CNRS, CEA, CFHT, and the Observatoire de Lyon published in the scientific journal Monthly Notices of the Royal Astronomical Society the first results from their study on two elliptical galaxies exhibiting features characteristic of a fairly recent merging, suggesting they are five times younger than commonly thought.
Continue reading “Elliptical galaxies much younger than previously thought? (CFHT press release)”The merger origin of a fast- and a slow-rotating early-type galaxy revealed with deep optical imaging
The final stages of mass assembly of present-day massive galaxies are expected to occur through the accretion of multiple satellites. Cosmological simulations thus predict a high frequency of stellar streams resulting from this mass accretion around the massive galaxies in the Local Volume. Such tidal streams are difficult to observe, especially in dense cluster environments, where they are readily destroyed. We present an investigation into the origins of a series of interlaced narrow filamentary stellar structures, loops and plumes in the vicinity of the Virgo Cluster, edge-on spiral galaxy, NGC 4216 that were previously identified by the Blackbird Telescope. Using the deeper, higher-resolution and precisely calibrated optical CFHT/MegaCam images obtained as part of the Next Generation Virgo Cluster Survey (NGVS), we confirm the previously identified features and identify a few additional structures.
Continue reading “The merger origin of a fast- and a slow-rotating early-type galaxy revealed with deep optical imaging”A Collisional Origin for the Leo Ring
Extended H I structures around galaxies are of prime importance for probing galaxy formation scenarios. The giant H I ring in the Leo group is one of the largest and most intriguing H I structures in the nearby universe. Whether it consists of primordial gas, as suggested by the apparent absence of any optical counterpart and the absence of an obvious physical connection to nearby galaxies, or of gas expelled from a galaxy in a collision is actively debated. We present deep wide field-of-view optical images of the ring region obtained with MegaCam on the CFHT.
Continue reading “A Collisional Origin for the Leo Ring”The mysterious Leo giant gas ring explained by a billion year old collision between two galaxies
An international team unveiled the origin of the giant gas ring in the Leo group of galaxies. With the Canada-France-Hawaii Telescope, the scientists were able to detect an optical signature of the ring corresponding to star forming regions. This observation rules out the primordial nature of the gas, which is of galactic origin. Thanks to numerical simulations made at CEA, a scenario for the formation of this ring has been proposed: a violent collision between two galaxies, slightly more than one billion years ago. The results will be published in the Astrophysical Journal Letters.
Continue reading “The mysterious Leo giant gas ring explained by a billion year old collision between two galaxies”