- ID:
- ivo://CDS.VizieR/J/ApJ/667/L145
- Title:
- HST Photometry of M82 region B
- Short Name:
- J/ApJ/667/L145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observations obtained with the Advanced Camera for Surveys on board the Hubble Space Telescope of the "fossil" starburst region B in the nearby starburst galaxy M82. By comparing UBVI photometry with models, we derive ages and extinctions for 35 U-band-selected star clusters. We find that the peak epoch of cluster formation occurred ~150Myr ago, in contrast to earlier work that found a peak formation age of 1.1Gyr. The difference is most likely due to our inclusion of U-band data, which are essential for accurate age determinations of young cluster populations. We further show that the previously reported turnover in the cluster luminosity function is probably due to the neglect of the effect of extended sources on the detection limit. The much younger cluster ages we derive clarifies the evolution of the M82 starburst. The M82-B age distribution now overlaps with the ages of the nuclear starburst, the clusters formed on the opposite side of the disk, and the last encounter with M81, some 220Myr ago.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AcA/59/47
- Title:
- HST photometry of M33 stellar clusters
- Short Name:
- J/AcA/59/47
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used deep ACS/WFC images of M33 to check the nature of extended objects detected by the ground based survey of Zloczewski et al. (2008, Cat. J/AcA/58/23). A total of 24 candidates turned out to be genuine compact stellar clusters. In addition we detected 91 new clusters. Equatorial coordinates, integrated magnitudes and angular sizes are listed for all 115 objects. Forty-two clusters have sufficiently red colors to be candidates for old globulars. For four clusters we extracted resolved stellar photometry. Object 33-3-018 located in the outer disk of M33 turned out to be a young cluster with an age estimated at 200-350Myr. Cluster ZK-90 has an age of 3-5Gyr. The remaining two clusters have intermediate ages ranging from one to a few Gyr.
- ID:
- ivo://CDS.VizieR/J/AJ/141/126
- Title:
- HST photometry of NGC 5471
- Short Name:
- J/AJ/141/126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We show that star formation in the giant HII region NGC 5471 has been ongoing during the past 100 Myr. Using Hubble Space Telescope/Wide-Field Planetary Camera 2 F547M and F675W, ground-based JHKs, and GALEX FUV and NUV images, we have conducted a photometric study of the star formation history (SFH) in the massive giant extragalactic HII region NGC 5471 in M101. We perform a photometric study of the color-magnitude diagram (CMD) of the resolved stars and an integrated analysis of the main individual star-forming clusters and of NGC 5471 as a whole.
- ID:
- ivo://CDS.VizieR/J/AJ/142/129
- Title:
- HST photometry of NGC 4449 clusters
- Short Name:
- J/AJ/142/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the star cluster population in the starburst irregular galaxy NGC 4449 based on B, V, I, and H{alpha} images taken with the Advanced Camera for Surveys on the Hubble Space Telescope. We derive cluster properties such as size, ellipticity, and total magnitude. Cluster ages and masses are derived fitting the observed spectral energy distributions with different population synthesis models.
- ID:
- ivo://CDS.VizieR/J/ApJ/668/209
- Title:
- HST photometry of NGC 5866 globulars
- Short Name:
- J/ApJ/668/209
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform a detailed study of the globular cluster (GC) system in the galaxy NGC 5866 based on F435W, F555W, and F625W (~B, V, and R) Hubble Space Telescope Advanced Camera for Surveys images. Adopting color, size, and shape selection criteria, the final list of GC candidates comprises 109 objects, with small estimated contamination from background galaxies, and foreground stars.
- ID:
- ivo://CDS.VizieR/J/A+A/550/A7
- Title:
- HST photometry of Sculptor group dwarf galaxies
- Short Name:
- J/A+A/550/A7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We focus on the resolved stellar populations of one early-type and four transition-type dwarf galaxies in the Sculptor group, with the aim to examine the potential presence of population gradients and place constraints on their mean metallicities. We use deep Hubble Space Telescope images to construct color-magnitude diagrams, from which we select stellar populations that trace different evolutionary phases in order to constrain their range of ages and metallicities, as well as to examine their spatial distribution. In addition, we use the resolved stars in the red giant branch in order to derive photometric metallicities.
- ID:
- ivo://CDS.VizieR/J/ApJ/766/20
- Title:
- HST photometry of star clusters in M82
- Short Name:
- J/ApJ/766/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a photometric study of star clusters in the nearby starburst galaxy M82 based on the UBVI-, YJ- and H-band Hubble Space Telescope images. We find 1105 star clusters with V<23mag. Of those, 1070 are located in the disk region, while 35 star clusters are in the halo region. The star clusters in the disk are composed of a dominant blue population with a color peak at (B-V)_0_~0.45, and a weaker red population. The luminosity function of the disk clusters shows a power-law distribution with a power-law index {alpha}=-2.04+/-0.03, and the scale height of their distribution is h_z_=9.64"+/-0.40" (164+/-7pc), similar to that of the stellar thin disk of M82. We have derived the ages of ~630 star clusters using the spectral energy distribution fit method by comparing UBVI(YJ)H-band photometric data with the simple stellar population models. The age distribution of the disk clusters shows that the most dominant cluster population has ages ranging from 100Myr to 1Gyr, with a peak at about 500Myr. This suggests that M82 has undergone a disk-wide star formation about 500Myr ago, probably through the interaction with M81. The brightest star clusters in the nuclear region are much brighter than those in other regions, indicating that more massive star clusters are formed in the denser environments. On the other hand, the colors of the halo clusters are similar to those of globular clusters in the Milky Way, and their ages are estimated to be older than 1Gyr. These are probably genuine old globular clusters in M82.
- ID:
- ivo://CDS.VizieR/J/AJ/151/23
- Title:
- HST photometry of stars in HD 97950
- Short Name:
- J/AJ/151/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use photometry in the F220W, F250W, F330W, F435W filters from the High Resolution Channel of the Advanced Camera for Surveys and photometry in the F555W, F675W, and F814W filters from the Wide Field and Planetary Camera 2 aboard the Hubble Space Telescope to derive individual stellar reddenings and extinctions for stars in the HD97950 cluster in the giant HII region NGC 3603. The mean line of sight reddening for about a hundred main-sequence member stars inside the cluster is E(F435W-F555W)=1.33+/-0.12mag. After correcting for foreground reddening, the total to selective extinction ratio is R_F555W_=3.75+/-0.87 in the cluster. Within the standard deviation associated with E({lambda}-F555W)/E(F435W-F555W) in each filter, the cluster extinction curve at ultraviolet wavelengths tends to be grayer than the average Galactic extinction laws from Cardelli et al. and Fitzpatrick. It is closer to the extinction law derived by Calzetti et al. for starburst galaxies, where the 0.2175{mu}m bump is absent. This indicates an anomalous extinction in the HD97950 cluster, which may due to the clumpy dust distribution within the cluster, and the size of dust grains being larger than the average Galactic ISM.
- ID:
- ivo://CDS.VizieR/J/AJ/136/2259
- Title:
- HST photometry of stars in NGC 2419
- Short Name:
- J/AJ/136/2259
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of optical and ultraviolet Hubble Space Telescope photometry for evolved stars in the core of the distant massive globular cluster NGC 2419. We characterize the horizontal branch (HB) population in detail including corrections for incompleteness on the long blue tail. The majority of the HB stars can be identified with two main groups (one slightly bluer than the instability strip, and the other at the extreme end of the HB). We present a method for removing (to first-order) lifetime effects from the distribution of HB stars to facilitate more accurate measurements of helium abundance for clusters with blue HBs and to clarify the distribution of stars reaching the zero-age HB.
- ID:
- ivo://CDS.VizieR/J/ApJ/673/143
- Title:
- HST photometry of TN J1338-1942
- Short Name:
- J/ApJ/673/143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep HST ACS observations in g_475_r_625_i_775_z_850_ toward the z=4.1 radio galaxy TN J1338-1942 and its overdensity of >30 spectroscopically confirmed Ly{alpha} emitters (LAEs). We select 66 g_475_ band dropouts to z_850,5sigma_=27, 6 of which are also LAEs.
