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3171. UV structure of 11 galaxies with Swift-UVOT
ID:
ivo://CDS.VizieR/J/A+A/602/A97
Title:
UV structure of 11 galaxies with Swift-UVOT
Short Name:
J/A+A/602/A97
Date:
21 Oct 2021
Publisher:
CDS
Description:
GALEX detected a significant fraction of early-type galaxies, in particular S0s, showing Far-UV bright structures, sometimes involving an entire galaxy out to its outskirts. These features suggest the presence of either recent, ongoing and/or prolonged star formation episodes, shedding new light on the evolution of these systems. We aim at understanding the evolutionary path[s] of these early-type galaxies and the mechanisms at the origin of their UV-bright structures. We investigate with a multi{lambda} approach the link between the inner and the outer galaxy regions of a set of eleven early-type galaxies selected because of their nearly passive stage of evolution in the nuclear region. This paper, second of a series, focuses on the information coming from the comparison between UV features detected by Swift-UVOT, tracing recent star formation, and the galaxy optical structure mapping older stellar populations. We performed a surface photometric study of these early-type galaxies, observed with Swift-UVOT UV filters, W2 2030{AA} {lambda_0}, M2 2231{AA} {lambda_0}, W1 2634{AA} {lambda_0}, and UBV bands. BVRI photometry from other sources in the literature is also used. Our integrated magnitude measurements have been analyzed and compared with corresponding values in the literature. We characterize the overall galaxy structure best fitting the UV and optical luminosity profiles using a single Sersic law. NGC 1366, NGC 1426, NGC 3818, NGC 3962 and NGC 7192 show featureless luminosity profiles. Excluding NGC~1366 which has a clear edge-on disk (n~1-2), and NGC 3818, the remaining three have Sersic's indices n~3-4 in optical and a lower index in the UV. Bright ring/arm-like structures are revealed by UV images and luminosity profiles of NGC 1415, NGC 1533, NGC 1543, NGC 2685, NGC 2974 and IC 2006. The ring/arm-like structures are different from galaxy to galaxy. Sersic indices of UV profiles for those galaxies are in the range n=1.5-3 both in S0s and in galaxies classified as "bona fide" ellipticals, such as NGC 2974 and IC 2006. We notice that in our sample optical Sersic indices are usually larger than in the UV ones. (M2-V) color profiles are bluer in ring/arm-like structures with respect to the galaxy body. The lower values of Sersic's indices in the UV bands with respect to optical ones, suggesting the presence of a disk, point out that the role of the dissipation cannot be neglected in recent evolutionary phases of these early-type galaxies.
3172. UV to far-IR photometry of galaxies
ID:
ivo://CDS.VizieR/J/ApJS/199/22
Title:
UV to far-IR photometry of galaxies
Short Name:
J/ApJS/199/22
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this paper, we present a sample of cluster galaxies devoted to study the environmental influence on the star formation activity. This sample of galaxies inhabits in clusters showing a rich variety in their characteristics and have been observed by the SDSS-DR6 down to M_B_~-18, and by the Galaxy Evolution Explorer AIS throughout sky regions corresponding to several megaparsecs. We assign the broadband and emission-line fluxes from ultraviolet to far-infrared to each galaxy performing an accurate spectral energy distribution for spectral fitting analysis. The clusters follow the general X-ray luminosity versus velocity dispersion trend of L_X_{propto}{sigma}^4.4^_c_.
3173. UV-to-IR fluxes of Hickson compact groups
ID:
ivo://CDS.VizieR/J/A+A/533/A142
Title:
UV-to-IR fluxes of Hickson compact groups
Short Name:
J/A+A/533/A142
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a comprehensive study on the impact of the environment of compact galaxy groups on the evolution of their members using a multi-wavelength analysis, from the UV to the infrared, for a sample of 32 Hickson compact groups (HCGs) containing 135 galaxies. Fitting the SEDs of all galaxies with the state-of-the-art model of da Cunha (2008MNRAS.388.1595D) we can accurately calculate their mass, SFR, and extinction, as well as estimate their infrared luminosity and dust content. We compare our findings with samples of field galaxies, early-stage interacting pairs, and cluster galaxies with similar data. We find that classifying the groups as dynamically "old" or "young", depending on whether or not at least one quarter of their members are early-type systems, is physical and consistent with past classifications of HCGs based on their atomic gas content. Dynamically "old" groups are more compact and display higher velocity dispersions than "young" groups. Late-type galaxies in dynamically "young" groups have specific star formation rates (sSFRs), NUV-r, and mid-infrared colors which are similar to those of field and early stage interacting pair spirals. Late-type galaxies in dynamically "old" groups have redder NUV-r colors, as they have likely experienced several tidal encounters in the past building up their stellar mass, and display lower sSFRs. We identify several late-type galaxies which have sSFRs and colors similar to those of elliptical galaxies, since they lost part of their gas due to numerous interactions with other group members. Also, 25% of the elliptical galaxies in these groups have bluer UV/optical colors than normal ellipticals in the field, probably due to star formation as they accreted gas from other galaxies of the group, or via merging of dwarf companions. Finally, our SED modeling suggests that in 13 groups, 10 of which are dynamically "old", there is diffuse cold dust in the intragroup medium. All this evidence point to an evolutionary scenario in which the effects of the group environment and the properties of the galaxy members are not instantaneous. Early on, the influence of close companions to group galaxies is similar to the one of galaxy pairs in the field. However, as the time progresses, the effects of tidal torques and minor merging, shape the morphology and star formation history of the group galaxies, leading to an increase of the fraction of early-type members and a rapid built up of the stellar mass in the remaining late-type galaxies.
3174. UV-UBV photometry in NGC 595
ID:
ivo://CDS.VizieR/J/AJ/111/1128
Title:
UV-UBV photometry in NGC 595
Short Name:
J/AJ/111/1128
Date:
21 Oct 2021
Publisher:
CDS
Description:
As part of a larger effort to study the resolved and composite properties of the giant H II regions in Messier 33, we have analyzed multiband HST/WFPC-2 images of NGC 595 in terms of the ionizing cluster's resolved stellar population. Photometric reductions of the PC images yield 100 stars in the UV image, 272 stars on the U image, 345 stars on the B image, and 561 stars on the V image. A total of 267 stars are common to the U, B, and V images while 86 stars are detected on all 4 images. Although some clustering is evident, the degree of central concentration is less than that seen in 30 Doradus. The resulting U-B vs B-V diagram of the resolved stars is used to determine the reddening of each star. The average reddening derived from this diagram is E(B-V)=0.36+/-0.28mag. The dereddened color-M_V diagram is best fit by a model cluster having an age of 4.5+/-1.0Myr, and hence initial masses no greater than 51M_{sun}_. A total of 13 supergiant stars and 10 candidate WR stars [Drissen et al. (1993AJ....105.1400D), and references therein] are identified with M_V=-5 to -8mag. The remainder are main-sequence O-type (98) and early B-type (>145) stars with M_V=-1 to -6mag. The ratio of WR to O stars is WR/O=0.11+/-0.01, roughly the same as found in the core of 30 Doradus. The resulting luminosity function has a slope of alpha=-0.71. The derived IMF has a slope of Gamma=-1.32+/-0.02 before subtracting a background component, and Gamma=-1.00+/-0.05 after subtracting a background based on photometry of the surrounding WF images. Integration of the derived IMF down to a lower mass limit of 4M_{sun}_ yields a total mass of 7350M_{sun}_, while integration down to 0.1_{Msun}_ yields a total mass of 18000M_{sun}_. The total estimated ionizing luminosity is 5.0x10^50photon/s, roughly half that which is inferred from the Halpha luminosity in this region. This shortfall of ionizing photons can be reconciled by allowing for a spread in the stellar ages, and/or increasing the modeled EUV luminosity of the stars at the inferred cluster age.
3175. UV variability and accretion in NGC 2264
ID:
ivo://CDS.VizieR/J/A+A/581/A66
Title:
UV variability and accretion in NGC 2264
Short Name:
J/A+A/581/A66
Date:
21 Oct 2021
Publisher:
CDS
Description:
Photometric variability is a distinctive feature of young stellar objects; exploring variability signatures at different wavelengths provides insight into the physical processes at work in these sources. We explore the variability signatures at ultraviolet (UV) and optical wavelengths for several hundred accreting and non-accreting members of the star-forming region NGC 2264 (~3Myr).
3176. Validated & new members of NGC 7000/IC 5070 Complex
ID:
ivo://CDS.VizieR/J/ApJ/899/128
Title:
Validated & new members of NGC 7000/IC 5070 Complex
Short Name:
J/ApJ/899/128
Date:
14 Mar 2022 07:05:45
Publisher:
CDS
Description:
We examine the clustering and kinematics of young stellar objects (YSOs) in the North America/Pelican Nebulae, as revealed by Gaia astrometry, in relation to the structure and motions of the molecular gas, as indicated in molecular-line maps. The Gaia parallaxes and proper motions allow us to significantly refine previously published lists of YSOs, demonstrating that many of the objects previously thought to form a distributed population turn out to be nonmembers. The members are subdivided into at least six spatio-kinematic groups, each of which is associated with its own molecular cloud component or components. Three of the groups are expanding, with velocity gradients of 0.3-0.5km/s/pc, up to maximum velocities of ~8km/s away from the groups' centers. The two known O-type stars associated with the region, 2MASS J20555125+4352246 and HD 199579, are rapidly escaping one of these groups, following the same position-velocity relation as the low-mass stars. We calculate that a combination of gas expulsion and tidal forces from the clumpy distribution of molecular gas could impart the observed velocity gradients within the groups. However, on a global scale, the relative motions of the groups do not appear either divergent or convergent. The velocity dispersion of the whole system is consistent with the kinetic energy gained due to gravitational collapse of the complex. Most of the stellar population has ages similar to the freefall timescales for the natal clouds. Thus, we suggest the nearly freefall collapse of a turbulent molecular cloud as the most likely scenario for star formation in this complex.
3177. VANDELS High-Redshift Galaxy Evolution
ID:
ivo://CDS.VizieR/V/151
Title:
VANDELS High-Redshift Galaxy Evolution
Short Name:
V/151
Date:
21 Oct 2021
Publisher:
CDS
Description:
VANDELS is a new ESO spectroscopic Public Survey targeting the high-redshift Universe. Exploiting the red sensitivity of the refurbished VIMOS spectrograph, the survey is obtaining ultra-deep optical spectroscopy of around 2100 galaxies in the redshift interval 1.0<z<7.0, with 85% of its targets selected to be at z>=3. The fundamental aim of the survey is to provide the high signal-to-noise spectra necessary to measure key physical properties such as stellar population ages, metallicities and outflow velocities from detailed absorption-line studies. By targeting two extragalactic survey fields with superb multi-wavelength imaging data, VANDELS will produce a unique legacy dataset for exploring the physics underpinning high-redshift galaxy evolution.
3178. V and Rc light curves of medium-bright PPNe
ID:
ivo://CDS.VizieR/J/AJ/159/21
Title:
V and Rc light curves of medium-bright PPNe
Short Name:
J/AJ/159/21
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present 10 years of new photometric monitoring of the light variability of five evolved stars with strong mid-infrared emission from surrounding dust. Three are known carbon-rich proto-planetary nebulae (PPNe) with F-G spectral types; the nature of the other two was previously unknown. For the three PPNe, we determine or refine the pulsation periods of IRAS04296+3429 (71 days), 06530-0213 (80 days), and 23304+6147 (84 days). A secondary period was found for each, with a period ratio P_2_/P_1_ of 0.9. The light variations are small, 0.1-0.2mag. These are similar to values found in other PPNe. The other two are found to be giant stars. IRAS09296+1159 pulsates with a period of only 47 days but reaches pulsational light variations of 0.5mag. Supplemental spectroscopy reveals the spectrum of a CH carbon star. IRAS08359-1644 is a G1III star that does not display pulsational variability; rather, it shows nonperiodic decreases of brightness of up to 0.5mag over this 10 year interval. These drops in brightness are reminiscent of the light curves of R Corona Borealis variables, but with much smaller decreases in brightness and are likely due to transient dust obscuration. Its spectral energy distribution is very similar to that of the unusual oxygen-rich giant star HDE233517, which possesses mid-infrared hydrocarbon emission features. These two non-PPNe turn out to be members of the rare group of giant stars with large mid-infrared excesses due to dust, objects which presumably have interesting evolutionary histories.
3179. Variability in C-rich proto-PNe.
ID:
ivo://CDS.VizieR/J/ApJ/709/1042
Title:
Variability in C-rich proto-PNe.
Short Name:
J/ApJ/709/1042
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have carried out long-term (14 years) V and R photometric monitoring of 12 carbon-rich proto-planetary nebulae. The light and color curves display variability in all of them. The light curves are complex and suggest multiple periods, changing periods, and/or changing amplitudes, which are attributed to pulsation. A dominant period has been determined for each and found to be in the range of ~150 days for the coolest (G8) to 35-40 days for the warmest (F3). A clear, linear inverse relationship has been found in the sample between the pulsation period and the effective temperature and also an inverse relationship between the amplitude of light variation and the effective temperature. These are consistent with the expectation for a pulsating post-asymptotic giant branch (post-AGB) star evolving toward higher temperature at constant luminosity. The published spectral energy distributions and mid-infrared images show these objects to have cool (200K), detached dust shells and published models imply that intensive mass loss ended 400-2000 years ago.
3180. Variability indexes of QSOs in SDSS Stripe 82
ID:
ivo://CDS.VizieR/J/A+A/525/A37
Title:
Variability indexes of QSOs in SDSS Stripe 82
Short Name:
J/A+A/525/A37
Date:
21 Oct 2021
Publisher:
CDS
Description:
We identified 8744 quasars in the Light-Motion Curve Catalogue (LMCC; Bramich et al., 2008MNRAS.386..887B, http://das.sdss.org/value_added/stripe_82_variability/SDSS_82_public/) for the stripe 82 of the Sloan Digital Sky Survey (SDSS). The light curves were used, after correction for photometric outliers, to compute individual noise-corrected first-order structure functions (variance as a function of time-lag) binned into rest frame time-lag intervals. The mean value of the corrected structure function at rest frame time-lags from 300 to 600 days is found to be a useful variability index for the statistical investigation of quasar samples with redshifts up to ~3. For each quasar, the variability indexes for the five SDSS bands are given along with the equatorial coordinates, redshift, mean g band magnitude, absolute i band magnitude, and a remark on spectral peculiarities.