With Cosmicflows-4, distances are compiled for 55,877 galaxies gathered into 38,065 groups. Eight... more With Cosmicflows-4, distances are compiled for 55,877 galaxies gathered into 38,065 groups. Eight methodologies are employed, with the largest numbers coming from the correlations between the photometric and kinematic properties of spiral galaxies (TF) and elliptical galaxies (FP). Supernovae that arise from degenerate progenitors (type Ia SNe) are an important overlapping component. Smaller contributions come from distance estimates from the surface brightness fluctuations of elliptical galaxies and the luminosities and expansion rates of core-collapse supernovae (SNe II). Cepheid period–luminosity relation and tip of the red giant branch observations founded on local stellar parallax measurements along with the geometric maser distance to NGC 4258 provide the absolute scaling of distances. The assembly of galaxies into groups is an important feature of the study in facilitating overlaps between methodologies. Merging between multiple contributions within a methodology and between ...
V. M. Kaspi (McGill University/Massachusetts Institute of Technology), J. Jensen (Gemini), F. Rig... more V. M. Kaspi (McGill University/Massachusetts Institute of Technology), J. Jensen (Gemini), F. Rigaut (Gemini), A. Hatakeyama (Gemini), P. M. Woods (USRA/NSSTC) report Gemini North 8-m near-IR observations of the anomalous X-ray pulsar 1E 2259+586 field. K_s band data were obtained on June 21, 2002 at 14:44 UT using the NIRI instrument and a 30-min exposure with seeing 0.7".
First, a status report is given for the on-going (Phase 2) instruments under construction now for... more First, a status report is given for the on-going (Phase 2) instruments under construction now for Gemini. These instruments will be deployed during 2006 and 2007 at Gemini-South and collectively represent the end of an era of instrument building within the Gemini ...
ABSTRACT We estimate the luminosity-weighted ages of 16 early-type galaxies in Virgo and Fornax c... more ABSTRACT We estimate the luminosity-weighted ages of 16 early-type galaxies in Virgo and Fornax clusters based upon the near-IR (F110W and F160W) SBF observations using the Hubble Space Telescope (HST). We compare the HST observations with the stellar population synthesis models using the Padova and the Teramo isochrones, respectively. We investigate and present how the alpha-element enhancement and the convective core overshoot affect the mean age and star formation history estimation.
Astrophysical Journal Supplement Series, May 1, 1988
Four LMC star clusters are examined whose colors suggest ages between 2 and 10 Gyr. Three of thes... more Four LMC star clusters are examined whose colors suggest ages between 2 and 10 Gyr. Three of these, NGC 1754, NGC 1795 and SL 506, have ages within the well-populated range from 0.8 to 3 Gyr. No conclusion can be reached about the age of NGC 2005, which is located in the Bar and very crowded. No cluster has yet
We measured Surface Brightness FluctuaIons (SBF) in three galaxies, ESO137-G006, NGC 3309, and NG... more We measured Surface Brightness FluctuaIons (SBF) in three galaxies, ESO137-G006, NGC 3309, and NGC 5128, using the GeMS MulIConjugate AdapIve OpIcs (MCAO) system on the Gemini South telescope. ESO137-G006 is located in the Norma Cluster, NGC 3309 is located in the Hydra Cluster, while NGC 5128, also known as Centaurus A, is a nearby galaxy with numerous other distance measurements, including Cepheids. These galaxies were observed as a path finder to establish the SBF technique using the MCAO system. The J and Ks-band images taken with MCAO were astrometrically corrected and combined using the THELI so_ware.1 This method allowed us to accurately account for the distorIons of the focal plane when combining the images. The foreground stars as well as the globular clusters were measured to account for their contribuIon to the SBF. (J-Ks) color measurements were made to calibrate SBF and determine the stellar populaIons of the galaxies. The results of these measurements give us an SBF ca...
Symposium - International Astronomical Union, 1994
We present observations of the 11 July 1991 total solar eclipse made from the Caltech Submillimet... more We present observations of the 11 July 1991 total solar eclipse made from the Caltech Submillimeter Observatory. The 850 μm limb is extended 3380±140 km above the visible limb, and there is a 10% brightening at the extreme limb. The measured limb height agrees with previous work at shorter and longer wavelengths. The run of limb heights with wavelength is well fit by a single electron density scale height. We argue that there is no need to invoke spicule geometry to explain the observations.
With Cosmicflows-4, distances are compiled for 55,877 galaxies gathered into 38,065 groups. Eight... more With Cosmicflows-4, distances are compiled for 55,877 galaxies gathered into 38,065 groups. Eight methodologies are employed, with the largest numbers coming from the correlations between the photometric and kinematic properties of spiral galaxies (TF) and elliptical galaxies (FP). Supernovae that arise from degenerate progenitors (type Ia SNe) are an important overlapping component. Smaller contributions come from distance estimates from the surface brightness fluctuations of elliptical galaxies and the luminosities and expansion rates of core-collapse supernovae (SNe II). Cepheid period–luminosity relation and tip of the red giant branch observations founded on local stellar parallax measurements along with the geometric maser distance to NGC 4258 provide the absolute scaling of distances. The assembly of galaxies into groups is an important feature of the study in facilitating overlaps between methodologies. Merging between multiple contributions within a methodology and between ...
V. M. Kaspi (McGill University/Massachusetts Institute of Technology), J. Jensen (Gemini), F. Rig... more V. M. Kaspi (McGill University/Massachusetts Institute of Technology), J. Jensen (Gemini), F. Rigaut (Gemini), A. Hatakeyama (Gemini), P. M. Woods (USRA/NSSTC) report Gemini North 8-m near-IR observations of the anomalous X-ray pulsar 1E 2259+586 field. K_s band data were obtained on June 21, 2002 at 14:44 UT using the NIRI instrument and a 30-min exposure with seeing 0.7".
First, a status report is given for the on-going (Phase 2) instruments under construction now for... more First, a status report is given for the on-going (Phase 2) instruments under construction now for Gemini. These instruments will be deployed during 2006 and 2007 at Gemini-South and collectively represent the end of an era of instrument building within the Gemini ...
ABSTRACT We estimate the luminosity-weighted ages of 16 early-type galaxies in Virgo and Fornax c... more ABSTRACT We estimate the luminosity-weighted ages of 16 early-type galaxies in Virgo and Fornax clusters based upon the near-IR (F110W and F160W) SBF observations using the Hubble Space Telescope (HST). We compare the HST observations with the stellar population synthesis models using the Padova and the Teramo isochrones, respectively. We investigate and present how the alpha-element enhancement and the convective core overshoot affect the mean age and star formation history estimation.
Astrophysical Journal Supplement Series, May 1, 1988
Four LMC star clusters are examined whose colors suggest ages between 2 and 10 Gyr. Three of thes... more Four LMC star clusters are examined whose colors suggest ages between 2 and 10 Gyr. Three of these, NGC 1754, NGC 1795 and SL 506, have ages within the well-populated range from 0.8 to 3 Gyr. No conclusion can be reached about the age of NGC 2005, which is located in the Bar and very crowded. No cluster has yet
We measured Surface Brightness FluctuaIons (SBF) in three galaxies, ESO137-G006, NGC 3309, and NG... more We measured Surface Brightness FluctuaIons (SBF) in three galaxies, ESO137-G006, NGC 3309, and NGC 5128, using the GeMS MulIConjugate AdapIve OpIcs (MCAO) system on the Gemini South telescope. ESO137-G006 is located in the Norma Cluster, NGC 3309 is located in the Hydra Cluster, while NGC 5128, also known as Centaurus A, is a nearby galaxy with numerous other distance measurements, including Cepheids. These galaxies were observed as a path finder to establish the SBF technique using the MCAO system. The J and Ks-band images taken with MCAO were astrometrically corrected and combined using the THELI so_ware.1 This method allowed us to accurately account for the distorIons of the focal plane when combining the images. The foreground stars as well as the globular clusters were measured to account for their contribuIon to the SBF. (J-Ks) color measurements were made to calibrate SBF and determine the stellar populaIons of the galaxies. The results of these measurements give us an SBF ca...
Symposium - International Astronomical Union, 1994
We present observations of the 11 July 1991 total solar eclipse made from the Caltech Submillimet... more We present observations of the 11 July 1991 total solar eclipse made from the Caltech Submillimeter Observatory. The 850 μm limb is extended 3380±140 km above the visible limb, and there is a 10% brightening at the extreme limb. The measured limb height agrees with previous work at shorter and longer wavelengths. The run of limb heights with wavelength is well fit by a single electron density scale height. We argue that there is no need to invoke spicule geometry to explain the observations.
The Great Observatories All-Sky LIRG Survey (GOALS 20) combines data from NASA's Spitzer Space Te... more The Great Observatories All-Sky LIRG Survey (GOALS 20) combines data from NASA's Spitzer Space Telescope, Chandra X-Ray Observatory, Hubble Space Telescope (HST), and Galaxy Evolution Explorer (GALEX) observatories, together with ground-based data, into a comprehensive imaging and spectroscopic survey of over 200 low-redshift (z < 0:088), Luminous Infrared Galaxies (LIRGs). The LIRGs are a complete subset of the IRAS Revised Bright Galaxy Sample (RBGS), which comprises 629 extragalactic objects with 60 μm flux densities above 5.24 Jy, and Galactic latitudes above five degrees. The LIRGs targeted in GOALS span the full range of nuclear spectral types defined via traditional optical line-ratio diagrams (type-1 and type-2 AGN, LINERs, and starbursts) as well as interaction stages (major mergers, minor mergers, and isolated galaxies). They provide an unbiased picture of the processes responsible for enhanced infrared emission in galaxies in the local Universe. As an example of the analytic power of the multiwavelength GOALS data set, we present Spitzer, Chandra, HST, and GALEX images and spectra for the interacting system VV 340 (IRAS F14547 þ 2449). The Spitzer MIPS imaging data indicates that between 80–95% of the total far-infrared emission (or about 5 × 10 11 L ⊙) originates in VV 340 north. While the Spitzer IRAC colors of VV 340 north and south are consistent with star-forming galaxies, both the Spitzer IRS and Chandra ACIS data indicate the presence of an AGN in VV 340 north. The observed line fluxes, without correction for extinction, imply that the AGN accounts for less than 10%–20% of the observed infrared emission. The X-ray data are consistent with a heavily absorbed (N H ≥ 10 24 cm À2) AGN. The GALEX far and near-UV fluxes imply a extremely large infrared " excess " (IRX) for the system (F IR =F fuv ∼ 81) which is well above the correlation seen in starburst galaxies. Most of this excess is driven by VV 340 N, which has an IR excess of nearly 400. The VV 340 system seems to be comprised of two very different galaxies: an infrared luminous edge-on galaxy (VV 340 north) that dominates the long-wavelength emission from the system, which hosts a buried AGN; and a face-on starburst (VV 340 south) that dominates the short-wavelength emission.
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Papers by Joseph Jensen