- ID:
- ivo://CDS.VizieR/J/A+A/437/87
- Title:
- Mrk 335 photometry in 1995-2004
- Short Name:
- J/A+A/437/87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of UBVRI photometry of Mrk 335 in 1995-2004. This object has a large amplitude of variability, reaching about 1.1, 0.9, 0.7mag in the U,B,V and 0.3mag in the Rc, Ic bands, respectively. ************************************************************************** * * * Sorry, but the author(s) never supplied the tabular material * * announced in the paper * * * **************************************************************************
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- ID:
- ivo://CDS.VizieR/J/ApJS/240/31
- Title:
- M-subdwarf research. I. LAMOST DR4 spectra obs.
- Short Name:
- J/ApJS/240/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We propose a revision of the system developed by Lepine+ (2007ApJ...669.1235L) for spectroscopic M-subdwarf classification. Based on an analysis of subdwarf spectra and templates from Savcheva+ (2014ApJ...794..145S), we show that the CaH1 feature originally proposed by Gizis (1997, J/AJ/113/806) is important in selecting reliable cool subdwarf spectra. This index should be used in combination with the [TiO5, CaH2+CaH3] relation provided by Lepine+ to avoid misclassification results. In the new system, the dwarf-subdwarf separators are first derived from a sample of more than 80000 M dwarfs and a "labeled" subdwarf subsample, and these objects are all visually identified from their optical spectra. Based on these two samples, we refit the initial [TiO5, CaH1] relation and propose a new [CaOH, CaH1] relation supplementing the [TiO5, CaH1] relation to reduce the impact of uncertainty in flux calibration on classification accuracy. In addition, we recalibrate the {zeta}TiO/CaH parameter defined in Lepine+ to enable its successful application to Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectra. Using this new system, we select candidates from LAMOST Data Release 4 and finally identify a set of 2791 new M-subdwarf stars, covering the spectral sequence from type M0 to M7. This sample contains a large number of objects located at low Galactic latitudes, especially in the Galactic anti-center direction, expanding beyond previously published halo- and thick disk-dominated samples. Besides, we detect magnetic activity in 141 objects. We present a catalog for this M-subdwarf sample, including radial velocities, spectral indices and errors, and activity flags, with a compilation of external data (photometric and Gaia Data Release 2 astrometric parameters).
- ID:
- ivo://CDS.VizieR/J/ApJS/243/28
- Title:
- M-type star magnetic activities from LAMOST & Kepler
- Short Name:
- J/ApJS/243/28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We performed a statistical study of magnetic activities of M-type stars by combining the spectra of LAMOST DR5 with light curves from the Kepler and K2 missions. We mainly want to study the relationship between chromospheric activity and flares, and their relations of magnetic activity and rotation period. We have obtained the maximum catalog of 516688 M-type stellar spectra of 480912 M stars from LAMOST-DR5 and calculated their equivalent widths of chromospheric activity indicators (H{alpha}, H{beta}, H{gamma}, H{delta}, CaII H&K, and HeI D3). Using the H{alpha} indicator, 40464 spectra of 38417 M stars show chromospheric activity, and 1791 of these 5499 M-type stars with repeated observations have H{alpha} variability. We used an automatic detection plus visual inspection method to detect 17432 flares on 8964 M-type stars from the catalog by cross-matching LAMOST DR5 and the Kepler and K2 databases. We used the Lomb-Scargle method to calculate their rotation periods. We find that the flare frequency is consistent with the ratio of activities of these chromospheric activity indicators as a function of spectral type in M0-M3. We find the equivalent widths of H{alpha} and CaII H have a significant statistical correlation with the flare amplitude in M-type stars. We confirm that the stellar flare is affected by both the stellar magnetic activity and the rotation period. Finally, using the H{alpha} equivalent width equal to 0.75{AA} and using the rotation period equal to 10 days as the threshold for the M-type stellar flare time frequency are almost equivalent.
- ID:
- ivo://CDS.VizieR/J/AJ/124/1486
- Title:
- M4 UBV color-magnitude diagrams
- Short Name:
- J/AJ/124/1486
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present UBV color-magnitude diagrams (CMDs) for the globular cluster M4. The CMDs show a sequence of four luminous blue stars (V<20, U-V<-0.6), which appear to be cluster hot subdwarfs. We present spectra for the three brightest ones. We also note the presence of a population of faint blue objects, likely to be hot, young white dwarfs belonging to the cluster. We have selected five objects above V=22mag, bright enough for follow-up ground-based spectroscopy, and present their coordinates and finding charts. We show a spectrum for variable V46, which suggests that it is a hot subdwarf, along with a new light curve obtained with the ISIS image subtraction package. The light curve is unstable, but only one period of variability is apparent. Two new variables have been discovered, both located on the cluster red giant branch. We also present a differential E(B-V) reddening map and a fiducial sequence for the main sequence, subgiant branch, and red giant branch on the V/B-V CMD for a selected region with uniform reddening. Based on a comparison with the M5 fiducial sequence, we obtain a reddening estimate of E(B-V)=0.41mag toward M4, consistent with previous determinations.
935. M30 UBV photometry
- ID:
- ivo://CDS.VizieR/J/AJ/116/1757
- Title:
- M30 UBV photometry
- Short Name:
- J/AJ/116/1757
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present F555W (V), F439W (B), and F336W (U) photometry of 9507 stars in the central 2' of the dense, post-core-collapse cluster M30 (NGC 7099) derived from Hubble Space Telescope Wide Field Planetary Camera 2 images. These data are used to study the mix of stellar populations in the central region of the cluster. Forty-eight blue straggler stars are identified; they are found to be strongly concentrated toward the cluster center. The specific frequency of blue stragglers, F_BSS_=N(BSS)/N(V<V_HB_+2), is 0.25+/-0.05 in the inner region of M30 (r<20"), significantly higher than the frequency found in other clusters: F_BSS_=0.05-0.15. The shape of M30's blue straggler luminosity function resembles the prediction of the collisional formation model, and is inconsistent with the binary merger model of Bailyn & Pinsonneault (1995ApJ...439..705B). An unusually blue star (B=18.6, B-V=-0.97), possibly a cataclysmic variable based on its color, is found about 1.2" from the crowded cluster center; the photometric uncertainty for this star is large, however, because of the presence of a very close neighbor. Bright red giant stars (B<16.6) appear to be depleted by a factor of 2-3 in the inner r<10" relative to fainter giants, subgiants, and main-sequence turnoff stars (95% significance). We confirm that there is a radial gradient in the color of the overall cluster light, going from B-V~0.82 at r~1' to B-V~0.45 in the central 10". The central depletion of the bright red giants is responsible for about half of the observed color gradient; the rest of the gradient is caused by the relative underabundance of faint red main-sequence stars near the cluster center (presumably a result of mass segregation). The luminosity function of M30's evolved stars does not match the luminosity function shape derived from standard stellar evolutionary models: the ratio of the number of bright giants to the number of turnoff stars in the cluster is 30% higher than predicted by the model (3.8{sigma} effect), roughly independent of red giant brightness over the range M_V_=-2 to +2.
- ID:
- ivo://CDS.VizieR/J/ApJ/743/154
- Title:
- Multi-band photometry of GRB 110205A + 110213A
- Short Name:
- J/ApJ/743/154
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present rich, early-time, multiband data sets for two Swift events, GRB 110205A and GRB 110213A. The former shows optical emission since the early stages of the prompt phase, followed by the steep rising in flux up to ~1000s after the burst (t^-{alpha}^ with {alpha}=-6.13+/-0.75). We discuss this feature in the context of the reverse-shock scenario and interpret the following single power-law decay as being forward-shock dominated. Polarization measurements, obtained with the RINGO2 instrument mounted on the Liverpool Telescope, also provide hints on the nature of the emitting ejecta. The latter event, instead, displays a very peculiar optical to near-infrared light curve, with two achromatic peaks. In this case, while the first peak is probably due to the onset of the afterglow, we interpret the second peak to be produced by newly injected material, signifying a late-time activity of the central engine.
- ID:
- ivo://CDS.VizieR/J/ApJ/897/180
- Title:
- Multiband photometry of microlensing event Kojima-1
- Short Name:
- J/ApJ/897/180
- Date:
- 16 Mar 2022 00:48:14
- Publisher:
- CDS
- Description:
- We report the lens mass and distance measurements of the nearby microlensing event TCPJ05074264+2447555 (Kojima-1). We measure the microlens parallax vector {pi}_E_ using Spitzer and ground-based light curves with constraints on the direction of lens-source relative proper motion derived from Very Large Telescope Interferometer (VLTI) GRAVITY observations. Combining this {pi}_E_ determination with the angular Einstein radius {theta}_E_ measured by VLTI-GRAVITY observations, we find that the lens is a star with mass M_L_=0.495{+/-}0.063M{odot} at a distance DL=429{+/-}21pc. We find that the blended light basically all comes from the lens. The lens-source proper motion is {mu}_rel,hel_=26.55{+/-}0.36mas/yr, so with currently available adaptive-optics instruments, the lens and source can be resolved in 2021. This is the first microlensing event whose lens mass is unambiguously measured by interferometry+satellite-parallax observations, which opens a new window for mass measurements of isolated objects such as stellar-mass black holes.
- ID:
- ivo://CDS.VizieR/J/PASP/122/144
- Title:
- Multiband photometry of V725 Sgr
- Short Name:
- J/PASP/122/144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- V725 Sgr is a rather peculiar variable that showed a period increase during part of the twentieth century. Its behavior is attributed to rapid stellar evolution. V725 Sgr was monitored in V, R, I and J, H, K with the REM telescope, on La Silla, from 2008 August to 2009 November. Its light variation does not show a well-defined cyclic behavior. Its current V is similar to what it was 30-40yrs ago. Its published motion suggests that V725 Sgr is located at a few kiloparsecs from the Sun. This implies that V725 Sgr is a giant rather than a supergiant star. From its mean colors we conclude that V725 Sgr is now an irregular variable of spectral type ~K4 III.
- ID:
- ivo://CDS.VizieR/J/A+A/556/A10
- Title:
- Multiband surface photometry of 21 BCGs
- Short Name:
- J/A+A/556/A10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep surface photometry of a volume-limited sample of 21 UM emission line galaxies in broadband optical UBVRI and near infra-red (NIR) HKs filters. The sample comprises 19 blue compact galaxies (BCGs) and two spirals. For some targets the exposure times are the deepest to date. For the BCG UM462 we observe a previously undetected second disk component beyond a surface brightness level of mu_B_=26mag/arcsec^2^. This is a true low surface brightness component with central surface brightness mu_0_=24.1mag/arcsec^2^ and scale length h_r_=1.5kpc. All BCGs are dwarfs, with M_B_>=-18, and very compact, with an average scale length of h_r_~1kpc. We separate the burst and host populations for each galaxy and compare them to stellar evolutionary models with and without nebular emission contribution. We also measure the A_180_ asymmetry in all filters and detect a shift from optical to NIR in the average asymmetry of the sample. This shift seems to be correlated with the morphological class of the BCGs. Using the color-asymmetry relation, we identify five BCGs in the sample as mergers, which is confirmed by their morphological class. Though clearly separated from normal galaxies in the concentration-asymmetry parameter space, we find that it is not possible to distinguish luminous starbursting BCGs from the merely star forming low luminosity BCGs.
- 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.
