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2821. The solar neighborhood .XXXX. New young stars
ID:
ivo://CDS.VizieR/J/AJ/154/151
Title:
The solar neighborhood .XXXX. New young stars
Short Name:
J/AJ/154/151
Date:
21 Oct 2021
Publisher:
CDS
Description:
As a step toward completing and characterizing the census of the solar neighborhood, we present astrometric, photometric, and spectroscopic observations of 32 systems observed with the Cerro Tololo Inter-American Observatory 0.9 m and 1.5 m telescopes. Astrometry from the 0.9 m indicates that among the 17 systems that had no previous published trigonometric parallaxes, 14 are within 25 pc. In the full sample, nine systems have proper motions larger than 0.5"/yr, including 2MASS J02511490-0352459, which exceeds 2.0"/yr. VRI photometry from the 0.9 m and optical spectra from the 1.5 m indicate that the targets have V=11-22 mag and spectral types M3.0V-L3.0V. For 2MASS J23062928-0502285 (TRAPPIST-1), we present updated astrometry and photometric variability based on over 12 years of observations. Of the nine binaries in the sample, two promise mass determinations in the next decade: LHS 6167AB, an M4.5V system for which we present an accurate parallax placing the binary at 9.7 pc, and 2MASS J23515048-2537367AB, an M8.5V system at 21.1 pc for which we present the first evidence of an unseen, low-mass companion. Most importantly, Na I and K I gravity indicators, H{alpha} measurements, long-term photometric variability, locations on the H-R diagram, and kinematic assessments indicate that as many as 13 of the systems are young, including candidate members of young moving groups, with ages less than ~120 Myr.
2822. The SOS project. IV. NGC 1624 and NGC 1931
ID:
ivo://CDS.VizieR/J/AJ/149/127
Title:
The SOS project. IV. NGC 1624 and NGC 1931
Short Name:
J/AJ/149/127
Date:
21 Oct 2021
Publisher:
CDS
Description:
Young open clusters located in the outer Galaxy provide us with an opportunity to study star formation activity in a different environment from the solar neighborhood. We present a UBVI and H{alpha} photometric study of the young open clusters NGC 1624 and NGC 1931 that are situated toward the Galactic anticenter. Various photometric diagrams are used to select the members of the clusters and to determine the fundamental parameters. NGC 1624 and NGC 1931 are, on average, reddened by <E(B-V)>=0.92+/-0.05 and 0.74+/-0.17mag, respectively. The properties of the reddening toward NGC 1931 indicate an abnormal reddening law (R_V,cl_=5.2+/-0.3). Using the zero-age main sequence fitting method we confirm that NGC 1624 is 6.0+/-0.6kpc away from the Sun, whereas NGC 1931 is at a distance of 2.3+/-0.2kpc. The results from isochrone fitting in the Hertzsprung-Russell diagram indicate the ages of NGC 1624 and NGC 1931 to be less than 4 and 1.5-2.0Myr, respectively. We derived the initial mass function (IMF) of the clusters. The slope of the IMF ({Gamma}_NGC1624_=-2.0+/-0.2 and {Gamma}_NGC1931_=-2.0+/-0.1) appears to be steeper than that of the Salpeter/Kroupa IMF. We discuss the implication of the derived IMF based on simple Monte-Carlo simulations and conclude that the property of star formation in the clusters does not seem to be significantly different from that in the solar neighborhood.
2823. The SOS. VII. UBVI photometry of open cluster IC 1590
ID:
ivo://CDS.VizieR/J/AJ/162/140
Title:
The SOS. VII. UBVI photometry of open cluster IC 1590
Short Name:
J/AJ/162/140
Date:
21 Mar 2022 00:39:36
Publisher:
CDS
Description:
Young open clusters are ideal laboratories to understand the star formation process. We present deep UBVI and H{alpha} photometry for the young open cluster IC1590 in the center of the HII region NGC281. Early-type members are selected from UBV photometric diagrams, and low-mass pre-main-sequence (PMS) members are identified by using H{alpha} photometry. In addition, the published X-ray source list and Gaia astrometric data are also used to isolate probable members. A total of 408 stars are selected as members. The mean reddening obtained from early-type members is <E(B-V)>=0.40{+/-}0.06(s.d.). We confirm the abnormal extinction law for the intracluster medium. The distance modulus to the cluster determined from the zero-age main-sequence fitting method is 12.3{+/-}0.2mag (d=2.88{+/-}0.28kpc), which is consistent with the distance d=2.70_-0.20_^+0.24^kpc from the recent Gaia parallaxes. We also estimate the ages and masses of individual members by means of stellar evolutionary models. The mode of the age of PMS stars is about 0.8Myr. The initial mass function of IC1590 is derived. It appears to be a steeper shape ({Gamma}=-1.49{+/-}0.14) than that of the Salpeter/Kroupa initial mass function for the high-mass regime (m>1M{sun}). The signature of mass segregation is detected from the difference in the slopes of the initial mass functions for the inner (r<2.5') and outer regions of this cluster. We finally discuss the star formation history in NGC281.
2824. The Spitzer Kepler Survey (SpiKeS) catalog
ID:
ivo://CDS.VizieR/J/ApJS/254/11
Title:
The Spitzer Kepler Survey (SpiKeS) catalog
Short Name:
J/ApJS/254/11
Date:
17 Jan 2022 00:38:57
Publisher:
CDS
Description:
The ~200000 targets monitored for photometric variability during the Kepler prime mission include the best-studied group of stars in the sky, due both to the extensive time history provided by Kepler and to the substantial amount of ancillary data provided by other investigators or compiled by the Kepler team. To complement this wealth of data, we surveyed the entire Kepler field using the 3.6 and 4.5{mu}m bands of the Warm Spitzer Space Telescope, obtaining photometry in both bands for almost 170000 objects. We demonstrate relative photometric precision ranging from better than ~1.5% for the brighter stars down to slightly greater than ~2% for the faintest stars monitored by Kepler. We describe the data collection and analysis phases of this work and identify several stars with large infrared excess, although none that is also known to be the host of an exoplanetary system.
2825. The Spitzer-SDSS-GALEX Spectroscopic Survey
ID:
ivo://CDS.VizieR/J/ApJ/741/79
Title:
The Spitzer-SDSS-GALEX Spectroscopic Survey
Short Name:
J/ApJ/741/79
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Spitzer-SDSS-GALEX Spectroscopic Survey (SSGSS) provides a new sample of 101 star-forming galaxies at z<0.2 with unprecedented multi-wavelength coverage. New mid- to far-infrared spectroscopy from the Spitzer Space Telescope is added to a rich suite of previous imaging and spectroscopy, including ROSAT, Galaxy Evolution Explorer, Sloan Digital Sky Survey, Two Micron All Sky Survey, and Spitzer/SWIRE. Sample selection ensures an even coverage of the full range of normal galaxy properties, spanning two orders of magnitude in stellar mass, color, and dust attenuation. In this paper we present the SSGSS data set, describe the science drivers, and detail the sample selection, observations, data reduction, and quality assessment.
2826. The SSRS2 Sample
ID:
ivo://CDS.VizieR/J/AJ/108/1987
Title:
The SSRS2 Sample
Short Name:
J/AJ/108/1987
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this paper we continue our investigation on the isophotal nature, accuracy, and uniformity of the magnitude system adopted in the Southern Sky Redshift Survey extension (SSRS2). Extending our earlier work, we examine galaxies in the equatorial region, primarily in the declination range -17.5 deg <= Dec. <= 0 deg, over a large range of right ascension, covering the southern and northern Galactic caps. For this purpose, we have obtained CCD isophotal magnitudes in the B and R bands for 265 galaxies of different morphological types. Using this larger sample we confirm our earlier claim that the m(SSRS2) magnitudes are very nearly the magnitude measured within the isophote mu_B = 26 mag/arcsec^2, with a dispersion of about 0.30 mag. The relative zero-point offset between our m(SSRS2) magnitudes and CCD photometry is -0.02 mag from all data we have obtained. However, we detect a variation of the zero-point across different regions of the sky of +/- 0.10 mag for regions at large angular separations. We also estimate that the zero-point offset between the m(SSRS2) and Zwicky systems is relatively small (~0.10 mag), which should allow us to combine the data from the SSRS2 and the CfA2 Redshift Survey.
2827. The stellar membership of the Taurus SFR
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.
2828. The supernovae Ia Pantheon sample
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.
2829. The Swan: an approach to derive surface gravity
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.
2830. The TESS Habitable Zone Star Catalog
ID:
ivo://CDS.VizieR/J/ApJ/874/L8
Title:
The TESS Habitable Zone Star Catalog
Short Name:
J/ApJ/874/L8
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the Transiting Exoplanet Survey Satellite (TESS) Habitable Zone Stars Catalog, a list of 1822 nearby stars with a TESS magnitude brighter than T=12 and reliable distances from Gaia DR2, around which the NASA's TESS mission can detect transiting planets, which receive Earth-like irradiation. For all those stars TESS is sensitive down to 2 Earth radii transiting planets during one transit. For 408 stars TESS can detect such planets down to 1 Earth-size during one transit. For 1690 stars, TESS has the sensitivity to detect planets down to 1.6 times Earth-size, a commonly used limit for rocky planets in the literature, receiving Earth-analog irradiation. We select stars from the TESS Candidate Target List, based on TESS Input Catalog Version 7. We update their distances using Gaia Data Release 2, and determine whether the stars will be observed for long enough during the 2yr prime mission to probe their Earth-equivalent orbital distance for transiting planets. We discuss the subset of 227 stars for which TESS can probe the full extent of the Habitable Zone, the full region around a star out to about a Mars-equivalent orbit. Observing the TESS Habitable Zone Catalog Stars will also give us deeper insight into the occurrence rate of planets, out to Earth-analog irradiation as well as in the Habitable Zone, especially around cool stars. We present the stars by decreasing angular separation of the 1 au equivalent distance to provide insights into which stars to prioritize for ground-based follow-up observations with upcoming extremely large telescopes.