- ID:
- ivo://CDS.VizieR/J/AJ/144/191
- Title:
- Multicolor photometry of 135 star clusters in M31
- Short Name:
- J/AJ/144/191
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present photometry for young star clusters in M31, which are selected from Caldwell et al. These star clusters have been observed as part of the Beijing-Arizona-Taiwan-Connecticut (BATC) Multicolor Sky Survey from 1995 February to 2008 March. The BATC images including these star clusters are taken with 15 intermediate-band filters covering 3000-10000{AA}. Combined with photometry in the GALEX far- and near-ultraviolet, broadband UBV RI, SDSS ugriz, and infrared JHK_s_ of Two Micron All Sky Survey, we obtain their accurate spectral energy distributions (SEDs) from 1538 to 20000{AA}. We derive these star clusters' ages and masses by comparing their SEDs with stellar population synthesis models. Our results are in good agreement with previous determinations. The mean value of age and mass of young clusters (<2Gyr) is about 385Myr and 2x10^4^M_{sun}_, respectively. There are two distinct peaks in the age distribution, a highest peak at age ~60Myr and a secondary peak around 250Myr, while the mass distribution shows a single peak around 10^4^M_{sun}_. A few young star clusters have two-body relaxation times greater than their ages, indicating that those clusters have not been well dynamically relaxed and therefore have not established the thermal equilibrium. There are several regions showing aggregations of young star clusters around the 10kpc ring and the outer ring, indicating that the distribution of the young star clusters is well correlated with M31's star-forming regions. The young massive star clusters (age<=100Myr and mass>=10^4^M_{sun}_) show apparent concentration around the ring splitting region, suggesting a recent passage of a satellite galaxy (M32) through M31 disk.
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- ID:
- ivo://CDS.VizieR/J/A+A/623/A65
- Title:
- Multiphotometry of M31 outer halo globular clusters
- Short Name:
- J/A+A/623/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present photometry of 53 globular clusters (GCs) in the M31 outer halo, including the GALEX FUV and NUV, SDSS ugriz, 15 intermediate-band filters of BATC, and 2MASS JHKs bands. By comparing the multicolour photometry with stellar population synthesis models, we determine the metallicities, ages, and masses for these GCs, aiming to probe the merging/accretion history of M31. We find no clear trend of metallicity and mass with the de-projected radius. The halo GCs with age younger than ~8Gyr are mostly located at the de-projected radii around 100kpc, but this may be due to a selection effect. We also find that the halo GCs have consistent metallicities with their spatially-associated substructures, which provides further evidence of the physical association between them. Both the disk and halo GCs in M31 show a bimodal luminosity distribution. However, we should emphasize that there are more faint halo GCs which are not being seen in the disk. There are more faint halo GCs than the disk ones, and these faint GCs constitute the fainter part in the luminosity function. The bimodal luminosity function of the halo GCs may reflect different origin or evolution environment in their original hosts. The M31 halo GCs includes one intermediate metallicity group (-1.5<[Fe/H]<-0.4) and one metal-poor group ([Fe/H]<-1.5), while the disk GCs have one metal-rich group more. There are considerable differences between the halo GCs in M31 and the Milky Way (MW). The total number of M31 GCs is approximately three times more numerous than that of the MW, however, M31 has about six times the number of halo GCs in the MW. Compared to M31 halo GCs, the Galactic halo ones are mostly metal-poor. Both the numerous halo GCs and the higher-metallicity component are suggestive of an active merger history of M31.
- ID:
- ivo://CDS.VizieR/J/A+A/546/A10
- Title:
- Multiplicity in transiting planet-host stars
- Short Name:
- J/A+A/546/A10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the exoplanetary era, the Kepler spacecraft is causing a revolution by discovering thousands of new planet candidates. However, a follow-up program is needed to reject false candidates and fully characterize the bona-fide exoplanets. Our main aims are to 1./ detect and analyze close companions inside the typical Kepler point spread function (PSF) to study whether they are the responsible for the dimming found in Kepler light curves, 2./ study the change in the stellar and planetary parameters caused by an unresolved object, 3./ help validate the Kepler objects of interest (KOI) that do not have any object inside the Kepler PSF, and 4./ study the multiplicity rate of planet-host candidates. Such a large sample of observed planet-host candidates allows us to derive statistics for close (visual or bounded) companions to the harboring star.
- ID:
- ivo://CDS.VizieR/J/ApJ/857/64
- Title:
- Multiwavelength catalog in the SEP field. II.
- Short Name:
- J/ApJ/857/64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For a sample of star-forming galaxies in the redshift interval 0.15<z<0.3, we study how both the relative strength of the active galactic nucleus (AGN) infrared emission, compared to that due to the star formation (SF), and the numerical fraction of AGNs change as a function of the total stellar mass of the hosting galaxy group (M_group_^*^) between 10^10.25^ and 10^11.9^M_{sun}_. Using a multicomponent spectral energy distribution SED fitting analysis, we separate the contribution of stars, AGN torus, and star formation to the total emission at different wavelengths. This technique is applied to a new multiwavelength data set in the SIMES field (23 not-redundant photometric bands), spanning the wavelength range from the UV (GALEX) to the far-IR (Herschel) and including crucial AKARI and WISE mid-IR observations (4.5{mu}m<{lambda}<24{mu}m), where the black hole thermal emission is stronger. This new photometric catalog, which includes our best photo-z estimates, is released through the NASA/IPAC Infrared Science Archive (IRSA). Groups are identified through a friends-of-friends algorithm (~62% purity, ~51% completeness). We identified a total of 45 galaxies requiring an AGN emission component, 35 of which are in groups and 10 in the field. We find the black hole accretion rate (BHAR){prop.to}(M_group_^*^)^1.21+/-0.27^ and (BHAR/SFR) {\prop} (M_group_^*^)^1.04+/- 0.24^, while, in the same range of M_group_^*^, we do not observe any sensible change in the numerical fraction of AGNs. Our results indicate that the nuclear activity (i.e., the BHAR and the BHAR/SFR ratio) is enhanced when galaxies are located in more massive and richer groups.
- ID:
- ivo://CDS.VizieR/J/ApJ/664/777
- Title:
- Multiwavelength study of RX J1117.4+0743
- Short Name:
- J/ApJ/664/777
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multiwavelength study of the poor cluster RX J1117.4+0743 ([VMF98] 097) at z=0.485, based on GMOS/Gemini South g' and r' photometry and spectroscopy, and XMM-Newton observations. We examine its nature and surroundings by analyzing the projected galaxy distribution, the galaxy velocity distribution, the weak-lensing mass reconstruction, and the X-ray spectroscopy and imaging.
- ID:
- ivo://CDS.VizieR/J/other/RAA/11.309
- Title:
- Nearby early-type galaxies in Stripe 82
- Short Name:
- J/other/RAA/11.3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We make use of the images from the Sloan Digital Sky Survey Stripe 82 (Stripe 82) to present an analysis of r band surface brightness profiles and radial color gradients (g-r, u-r) in our sample of 111 nearby early-type galaxies (ETGs). Thanks to the Stripe 82 images, each of which is co-added from about 50 single frames, we are able to pay special attention to the low-surface-brightness areas (LSB areas) of the galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/581/A33
- Title:
- Nearby radio galaxies FUV to MIR properties
- Short Name:
- J/A+A/581/A33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate whether the far-UV continuum of nearby radio galaxies is due solely to the parent galaxy that passively evolves, or if it reveals evidence for the presence of other star-forming or non-stellar components. If the UV excess is due to an additional radiation component, we compare this with other properties such as radio power, optical spectral type (e.g. high- and low-excitation galaxies), and the strength of the emission lines. We also discuss the possible correlation between the ultraviolet flux, IR properties, and the central black hole mass. We used a sample of low-luminosity B2 radio galaxies and a small sample of higher luminosity 3C radio galaxies at comparable redshift (z<0.2). Spectral energy distributions (SEDs) were constructed using a number of on-line databases that are freely available now: GALEX, SDSS, 2MASS, and WISE. These were compared with model SEDs of early-type galaxies with passively evolving stellar populations at various ages (typically 0.5-1.3x10^9^ years). We established whether a second component was needed to obtain a satisfactory fit with the observed overall SED. We introduce the parameter XUV, which measures the excess slope of the UV continuum between 4500 and 2000{AA} with respect to the UV radiation produced by the underlying old galaxy component. We find that the UV excess as measured by XUV is usually small or absent in low-luminosity (FR I) sources, but sets in abruptly at the transition radio power, above which we find mostly FRII sources. XUV behaves very similarly to the strength of the optical emission lines (in particular H{alpha}). Below P_1.4GHz_<10^24^W/Hz XUV is close to zero. XUV correlates strongly with the H{alpha} line strength, but only in sources with strong H{alpha} emission. We discuss whether the line emission might be due to photoionization by radiation from the parent galaxy, possibly with additional star formation, or if it requires the presence of a non-stellar active galactic nucleus component. XUV and the slope of the mid-IR are strongly correlated, as measured by the WISE bands in the interval 3.4 to 22{mu}m, in the sense that sources with a strong UV excess also have stronger IR emission. There is an inverse correlation between XUV and central black hole mass: the M_BH_ of objects with strong UV excess is on average two to three times less massive than that of objects without UV excess. Low-luminosity radio galaxies tend to be more massive and contain more massive black holes.
- ID:
- ivo://CDS.VizieR/J/ApJ/753/125
- Title:
- Near-IR spectroscopy follow-up of 60 SDSS-DR7 QSOs
- Short Name:
- J/ApJ/753/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Single-epoch virial black hole (BH) mass estimators utilizing broad emission lines have been routinely applied to high-redshift quasars to estimate their BH masses. Depending on the redshift, different line estimators (H{alpha}, H{beta}, MgII{lambda}2798, CIV{lambda}1549) are often used with optical/near-infrared spectroscopy. Here, we use a homogeneous sample of 60 intermediate-redshift (z~1.5-2.2) Sloan Digital Sky Survey quasars with optical and near-infrared spectra covering CIV through H{alpha} to investigate the consistency between different single-epoch virial BH mass estimators.
- ID:
- ivo://CDS.VizieR/J/MNRAS/450/3490
- Title:
- 15 new brown dwarfs in Orion OB1a/25 Ori group
- Short Name:
- J/MNRAS/450/3490
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of 15 new brown dwarfs belonging to the ~7Myr old 25 Orionis group and Orion OB1a subassociation with spectral types between M6 and M9 and estimated masses between ~0.07 and ~0.01M_{sun}_. By comparing them through a Bayesian method with low-mass stars (0.8<~M/M_{sun}_ <~0.1) from previous works in the 25 Orionis group, we found statistically significant differences in the number fraction of classical T Tauri stars, Weak T Tauri stars, class II, evolved discs and purely photospheric emitters at both sides of the substellar mass limit. Particularly, we found a fraction of 3.9^+2.4^_-1.6_ percent low-mass stars classified as Classic T Tauri star and class II or evolved discs, against a fraction of 33.3^+10.8^_-9.8_ percent in the substellar mass domain. Our results support the suggested scenario in which the dissipation of discs is less efficient for decreasing mass of the central object.
- ID:
- ivo://CDS.VizieR/J/other/RAA/15.1671
- Title:
- New carbon stars from LAMOST survey
- Short Name:
- J/other/RAA/15.1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Carbon stars are excellent kinematic tracers of galaxies and can serve as a viable standard candle, so it is worthwhile to automatically search for them in a large amount of spectra. In this paper, we apply the efficient manifold ranking algorithm to search for carbon stars from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) pilot survey, whose performance and robustness are verified comprehensively with four test experiments. Using this algorithm, we find a total of 183 carbon stars, and 158 of them are new findings. According to different spectral features, our carbon stars are classified as 58 C-H stars, 11 C-H star candidates, 56 C-R stars, ten C-R star candidates, 30 C-N stars, three C-N star candidates, and four C-J stars. There are also ten objects which have no spectral type because of low spectral quality, and a composite spectrum consisting of a white dwarf and a carbon star. Applying the support vector machine algorithm, we obtain the linear optimum classification plane in the J-H versus H-Ks color diagram which can be used to distinguish C-H from C-N stars with their J-H and H-Ks colors. In addition, we identify 18 dwarf carbon stars with their relatively high proper motions, and find three carbon stars with FUV detections likely have optical invisible companions by cross matching with data from the Galaxy Evolution Explorer. In the end, we detect four variable carbon stars with the Northern Sky Variability Survey, the Catalina Sky Survey and the LINEAR variability databases. According to their periods and amplitudes derived by fitting light curves with a sinusoidal function, three of them are likely semiregular variable stars and one is likely a Mira variable star.
