- ID:
- ivo://CDS.VizieR/J/AJ/138/1243
- Title:
- The star formation history of the LMC
- Short Name:
- J/AJ/138/1243
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first ever global, spatially resolved reconstruction of the star formation history (SFH) of the Large Magellanic Cloud (LMC), based on the application of our StarFISH analysis software to the multiband photometry of 20 million of its stars from the Magellanic Clouds Photometric Survey (MCPS). The general outlines of our results are consistent with previously published results: following an initial burst of star formation, there was a quiescent epoch from approximately 12 to 5Gyr ago. Star formation then resumed and has proceeded until the current time at an average rate of roughly 0.2M_{sun}_/yr, with temporal variations at the factor of 2 level.
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- ID:
- ivo://CDS.VizieR/J/AN/334/673
- Title:
- The stellar content of Trumpler 37
- Short Name:
- J/AN/334/673
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With an apparent cluster diameter of 1.5deg and an age of ~4Myr, Trumpler 37 is an ideal target for photometric monitoring of young stars as well as for the search of planetary transits, eclipsing binaries and other sources of variability. The YETI consortium has monitored Trumpler 37 throughout 2010 and 2011 to obtain a comprehensive view of variable phenomena in this region. In this first paper we present the cluster properties and membership determination as derived from an extensive investigation of the literature. We also compared the coordinate list to some YETI images. For 1872 stars we found literature data. Among them 774 have high probability of being member and 125 a medium probability. Based on infrared data we re-calculate a cluster extinction of 0.9-1.2mag. We can confirm the age and distance to be 3-5Myr and ~870pc. Stellar masses are determined from theoretical models and the mass function is fitted with a power-law index of {alpha}=1.90 (0.1-0.4M_{sun}_) and {alpha}=1.12 (1-10M_{sun}_).
- ID:
- ivo://CDS.VizieR/J/AJ/156/271
- Title:
- The stellar membership of the Taurus SFR
- Short Name:
- J/AJ/156/271
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The high-precision astrometry from the second data release of the Gaia mission (Cat. I/345) has made it possible to greatly improve the census of members of nearby clusters and associations. I have applied the Gaia data to the Taurus star-forming region, refining the sample of known members and identifying candidates for undiscovered members. The resulting samples of members and candidates provide the best constraints to date on the distribution of ages and the initial mass function (IMF) in Taurus. Several studies over the last 30 years have proposed the existence of a population of older stars (>~10 Myr) that is associated with the Taurus clouds. The data from Gaia demonstrate that such a population does not exist. Meanwhile, previous IMF estimates for small fields surrounding the Taurus aggregates have exhibited a surplus of K7-M0 stars (0.7-0.8 M_{sun}_) relative to star-forming clusters such as IC 348 and the Orion Nebula Cluster. However, that difference disappears when the new census of the entire region is considered, which should be complete for spectral types earlier than M6-M7 at A_J_<1. Thus, there is little variation in the stellar IMF across the 3-4 orders of magnitude in stellar density that are present in nearby star-forming regions. Finally, I note that the proper motions of two previously known members, KPNO 15 and 2MASS J04355209+2255039, indicate that they may have been ejected from the same location within the L1536 cloud ~7200 years ago.
- ID:
- ivo://CDS.VizieR/J/ApJS/107/201
- Title:
- The Stromlo-APM Redshift Survey IV
- Short Name:
- J/ApJS/107/201
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Stromlo-APM Redshift Survey consists of 1797 galaxies with b(J)<17.15 selected randomly at a rate of 1 in 20 from Automated Plate Measurement (APM) scans. The survey covers a solid angle of 1.3sr (4300 square degrees) in the south galactic cap. Redshifts have been measured for 1790 (99.6%) of the galaxies. The median galaxy recession velocity is 15,300 km/s and so the volume probed is approximately V=1.38 million Mpc^3/h^3.
- ID:
- ivo://CDS.VizieR/J/ApJ/859/101
- Title:
- The supernovae Ia Pantheon sample
- Short Name:
- J/ApJ/859/101
- Date:
- 20 Jan 2022 07:41:10
- Publisher:
- CDS
- Description:
- We present optical light curves, redshifts, and classifications for 365 spectroscopically confirmed Type Ia supernovae (SNe Ia) discovered by the Pan-STARRS1 (PS1) Medium Deep Survey. We detail improvements to the PS1 SN photometry, astrometry, and calibration that reduce the systematic uncertainties in the PS1 SN Ia distances. We combine the subset of 279 PS1 SNe Ia (0.03<z<0.68) with useful distance estimates of SNe Ia from the Sloan Digital Sky Survey (SDSS), SNLS, and various low-z and Hubble Space Telescope samples to form the largest combined sample of SNe Ia, consisting of a total of 1048 SNe Ia in the range of 0.01<z<2.3, which we call the "Pantheon Sample". When combining Planck 2015 cosmic microwave background (CMB) measurements with the Pantheon SN sample, we find {Omega}_m_=0.307+/-0.012 and w=-1.026+/-0.041 for the wCDM model. When the SN and CMB constraints are combined with constraints from BAO and local H_0_ measurements, the analysis yields the most precise measurement of dark energy to date: w_0_=-1.007+/-0.089 and w_a_=-0.222+/-0.407 for the w_0_w_a_CDM model. Tension with a cosmological constant previously seen in an analysis of PS1 and low-z SNe has diminished after an increase of 2x in the statistics of the PS1 sample, improved calibration and photometry, and stricter light-curve quality cuts. We find that the systematic uncertainties in our measurements of dark energy are almost as large as the statistical uncertainties, primarily due to limitations of modeling the low-redshift sample. This must be addressed for future progress in using SNe Ia to measure dark energy.
- ID:
- ivo://CDS.VizieR/J/AJ/113/634
- Title:
- The survival of Sagittarius dwarf galaxy
- Short Name:
- J/AJ/113/634
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Sagittarius dwarf spheroidal galaxy, the closest satellite galaxy of the Milky Way, has survived for many orbits about the Galaxy. Extent numerical calculations modeled this galaxy as a system with a centrally-concentrated mass profile, following the light, and found that it should lose more than one-half of its mass every 2-4 orbits and be completely disrupted long before now. Apparently the Sagittarius dwarf spheroidal, and by implication other dSph galaxies, do not have a centrally-concentrated profile for their dark matter. We develop a model in which the stars of the Sgr dwarf are embedded in a constant-density dark matter halo, representing the core of a tidally-limited system, and show that this is consistent with its survival. We present new photometric and kinematic observations of the Sagittarius dwarf spheroidal and show these data are consistent with this explanation for the continued existence of this galaxy. The Sagittarius dwarf is being tidally distorted and is tidally limited, but is not disrupted as yet. The corresponding minimum total mass is 10^9^M_{sun}_, while the central mass to visual light ratio is ~50 in Solar units. Our new photographic photometry allows the detection of main-sequence stars of the Sagittarius dwarf over an area of 22x8{deg}. The Sagittarius dwarf is prolate, with axis ratios ~3:1:1. For an adopted distance of 16+/-2kpc from the Galactic center on the opposite side of the Galaxy to the Sun, the major axis is >~9kpc long and is aligned approximately normal to the plane of the Milky Way Galaxy, roughly following the coordinate line l=5{deg}. The central velocity dispersion of giant stars which are members of the Sagittarius dwarf is 11.4+/-0.7km/s and is consistent with being constant over the face of the galaxy. The gradient in mean line-of-sight velocity with position along the major axis, dv/db, is ~0km/s/degree in the central regions and increases in amplitude to dv/db=-3km/s/degree over the outermost three degrees for which we have data. A first measurement of the proper motion of the Sagittarius dwarf determines the component of its space velocity parallel to its major axis to be 250+/-90km/s, directed towards the Galactic Plane. We model these kinematic data to determine the orbit of the Sagittarius dwarf. Our best fit model has an orbital period of <~1Gyr and has the Sagittarius dwarf spheroidal close to perigalacticon. This period is shorter, by about a factor of >~10, than the age of the bulk of its stellar population. (Copyright) 1997 American Astronomical Society.
- ID:
- ivo://CDS.VizieR/J/AJ/161/170
- Title:
- The Swan: an approach to derive surface gravity
- Short Name:
- J/AJ/161/170
- Date:
- 20 Jan 2022
- Publisher:
- CDS
- Description:
- Stellar light curves are well known to encode physical stellar properties. Precise, automated, and computationally inexpensive methods to derive physical parameters from light curves are needed to cope with the large influx of these data from space-based missions such as Kepler and TESS. Here we present a new methodology that we call "The Swan", a fast, generalizable, and effective approach for deriving stellar surface gravity (logg) for main-sequence, subgiant, and red giant stars from Kepler light curves using local linear regression on the full frequency content of Kepler long-cadence power spectra. With this inexpensive data-driven approach, we recover logg to a precision of ~0.02dex for 13822 stars with seismic logg values between 0.2 and 4.4dex and ~0.11dex for 4646 stars with Gaia-derived logg values between 2.3 and 4.6dex. We further develop a signal-to-noise metric and find that granulation is difficult to detect in many cool main-sequence stars (Teff<~5500K), in particular K dwarfs. By combining our logg measurements with Gaia radii, we derive empirical masses for 4646 subgiant and main-sequence stars with a median precision of ~7%. Finally, we demonstrate that our method can be used to recover logg to a similar mean absolute deviation precision for a TESS baseline of 27days. Our methodology can be readily applied to photometric time series observations to infer stellar surface gravities to high precision across evolutionary states.
- ID:
- ivo://CDS.VizieR/J/A+AS/125/497
- Title:
- Theta Vir and 109 Vir uvby photometry
- Short Name:
- J/A+AS/125/497
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Differential Stroemgren uvby photometric observations from the Four College Automated Photoelectric Telescope are used to examine the possible variability of the spectrophotometric standards {theta} Vir and 109 Vir. No evidence is found for variability within a season of observation. Small year to year differences are most likely due to unaccounted for extinction changes.
- ID:
- ivo://CDS.VizieR/J/AJ/156/102
- Title:
- The TESS Input Catalog and Candidate Target List
- Short Name:
- J/AJ/156/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Transiting Exoplanet Survey Satellite (TESS) will be conducting a nearly all-sky photometric survey over two years, with a core mission goal to discover small transiting exoplanets orbiting nearby bright stars. It will obtain 30 minute cadence observations of all objects in the TESS fields of view, along with two-minute cadence observations of 200000-400000 selected stars. The choice of which stars to observe at the two-minute cadence is driven by the need to detect small transiting planets, which leads to the selection of primarily bright, cool dwarfs. We describe the catalogs assembled and the algorithms used to populate the TESS Input Catalog (TIC), including plans to update the TIC with the incorporation of the Gaia second data release (Cat. I/345) in the near future. We also describe a ranking system for prioritizing stars according to the smallest transiting planet detectable, and assemble a Candidate Target List (CTL) using that ranking. We discuss additional factors that affect the ability to photometrically detect and dynamically confirm small planets, and we note additional stellar populations of interest that may be added to the final target list. The TIC is available on the STScI MAST server, and an enhanced CTL is available through the Filtergraph data visualization portal system at the URL http://filtergraph.vanderbilt.edu/tess_ctl.
- ID:
- ivo://CDS.VizieR/J/A+A/643/A15
- Title:
- The tidal tails in NGC7099
- Short Name:
- J/A+A/643/A15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results on the extra-tidal features of the Milky Way globular cluster NGC 7099, using deep gr photometry obtained with the Dark Energy Camera (DECam). We reached nearly 6mag below the cluster's main sequence (MS) turnoff, so that we dealt with the most suitable candidates to trace any stellar structure located beyond the cluster tidal radius. From star-by-star reddening corrected color-magnitude diagrams (CMDs), we defined four adjacent strips along the MS, for which we built the respective stellar density maps, once the contamination by field stars was properly removed. The resulting, cleaned, field star stellar density maps show a short tidal tail and some scattered debris. Such extra-tidal features are hardly detected when much shallower Gaia DR2 data sets are used and the same CMD field star cleaning procedure is applied. Indeed, by using 2.5mag below the MS turnoff of the cluster as the faintest limit (G<20.5mag), cluster members turned out to be distributed within the cluster's tidal radius, and some hints for field star density variations are found across a circle of radius 3.5{deg} centered on the cluster and with similar CMD features as cluster stars. The proper motion distribution of these stars is distinguishable from that of the cluster, with some superposition, which resembles that of stars located beyond 3.5{deg} from the cluster center.
