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3691. Low-mass population in L1641
ID:
ivo://CDS.VizieR/J/ApJ/752/59
Title:
Low-mass population in L1641
Short Name:
J/ApJ/752/59
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results from an optical photometric and spectroscopic survey of the young stellar population in L1641, the low-density star-forming region of the Orion A cloud south of the Orion Nebula Cluster (ONC). Our goal is to determine whether L1641 has a large enough low-mass population to make the known lack of high-mass stars a statistically significant demonstration of environmental dependence of the upper mass stellar initial mass function (IMF). Our spectroscopic sample consists of IR-excess objects selected from the Spitzer/IRAC survey and non-excess objects selected from optical photometry. We have spectral confirmation of 864 members, with another 98 probable members; of the confirmed members, 406 have infrared excesses and 458 do not. Assuming the same ratio of stars with and without IR excesses in the highly extincted regions, L1641 may contain as many as ~1600 stars down to ~0.1M_{sun}_, comparable within a factor of two to the ONC. Compared to the standard models of the IMF, L1641 is deficient in O and early B stars to a 3{sigma}-4{sigma} significance level, assuming that we know of all the massive stars in L1641.
3692. Low-mass population in {rho} Oph cloud
ID:
ivo://CDS.VizieR/J/A+A/515/A75
Title:
Low-mass population in {rho} Oph cloud
Short Name:
J/A+A/515/A75
Date:
21 Oct 2021
Publisher:
CDS
Description:
Star formation theories are currently divergent regarding the fundamental physical processes that dominate the substellar regime. Observations of nearby young open clusters allow the brown dwarf (BD) population to be characterised down to the planetary mass regime, which ultimately must be accommodated by a successful theory. We used near-IR deep images (reaching completeness limits of approximately 20.5mag in J, and 18.9mag in H and Ks taken with the Wide Field IR Camera (WIRCam) at the Canada France Hawaii Telescope (CFHT) to identify candidate members of {rho} Oph in the substellar regime. A spectroscopic follow-up of a small sample of the candidates allows us to assess their spectral type, and subsequently their temperature and membership. We select 110 candidate members of the {rho} Ophiuchi molecular cloud, from which 80 have not previously been associated with the cloud. We observed a small sample of these and spectroscopically confirm six new brown dwarfs with spectral types ranging from M6.5 to M8.25.
3693. Low-mass SDSS dwarf galaxy properties
ID:
ivo://CDS.VizieR/J/ApJ/653/240
Title:
Low-mass SDSS dwarf galaxy properties
Short Name:
J/ApJ/653/240
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate the gas content and baryonic Tully-Fisher relationship for extremely low luminosity dwarf galaxies in the absolute magnitude range -13.5>M_r_-5logh_70_>-16. The sample is selected from the Sloan Digital Sky Survey and consists of 101 galaxies for which we have obtained follow-up HI observations using the Arecibo Observatory and Green Bank Telescope. This represents the largest homogeneous sample of dwarf galaxies at low luminosities with well-measured HI and optical properties. The sample spans a range of environments, from dense groups to truly isolated galaxies.
3694. Low-mass stars and brown dwarfs in Blanco 1
ID:
ivo://CDS.VizieR/J/A+A/471/499
Title:
Low-mass stars and brown dwarfs in Blanco 1
Short Name:
J/A+A/471/499
Date:
21 Oct 2021
Publisher:
CDS
Description:
We performed a deep wide field optical survey of the young (~100-150Myr) open cluster Blanco 1 to study its low mass population well down into the brown dwarf regime and estimate its mass function over the whole cluster mass range.
3695. Low-mass stars and brown dwarfs in NGC 2024
ID:
ivo://CDS.VizieR/J/ApJ/646/1215
Title:
Low-mass stars and brown dwarfs in NGC 2024
Short Name:
J/ApJ/646/1215
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results from a near-infrared spectroscopic study of candidate brown dwarfs and low-mass stars in the young cluster NGC 2024. Using FLAMINGOS on the KPNO 2.1m and 4m telescopes, we have obtained spectra of ~70 new members of the cluster and classified them via the prominent J- and H-band water absorption features. Derived spectral types range from ~M1 to later than M8 with typical classification errors of 0.5-1 subclasses. By combining these spectral types with JHK photometry, we place these objects on the H-R diagram and use pre-main-sequence evolutionary models to infer masses and ages. The mean age for this low-mass population of NGC 2024 is 0.5Myr, and derived masses range from ~0.7 to 0.02M_{sun}_ with 23 objects falling below the hydrogen-burning limit. The logarithmic mass function rises to a peak at ~0.2M_{sun}_ before turning over and declining into the substellar regime. There is a possible secondary peak at ~0.035M_{sun}_ ; however, the errors are also consistent with a flat IMF in this region. The ratio of brown dwarfs to stars is similar to that found in the Trapezium but roughly twice the ratio found in IC 348, leading us to conclude that the substellar IMF in young clusters may be dependent on the local star-forming environment.
3696. Low-mass stars and brown dwarfs in Praesepe
ID:
ivo://CDS.VizieR/J/MNRAS/408/2457
Title:
Low-mass stars and brown dwarfs in Praesepe
Short Name:
J/MNRAS/408/2457
Date:
21 Oct 2021
Publisher:
CDS
Description:
Presented are the results of a large and deep optical-near-infrared multi-epoch survey of the Praesepe open star cluster using data from the UKIRT Infrared Deep Sky Survey (UKIDSS) Galactic Clusters Survey. Multiple colour-magnitude diagrams were used to select potential members and proper motions were used to assign levels of membership probability. From our sample, 145 objects were designated as high probability members (p>=0.6) with most of these having been found by previous surveys although 14 new cluster members are also identified. Our membership assignment is restricted to the bright sample of objects (Z<18). From the fainter sample, 39 candidates were found from an examination of multiple colour-magnitude plots.
3697. Low-mass stars evolutionary models
ID:
ivo://CDS.VizieR/J/A+A/337/403
Title:
Low-mass stars evolutionary models
Short Name:
J/A+A/337/403
Date:
21 Oct 2021
Publisher:
CDS
Description:
Physical properties and absolute magnitudes of low-mass stars for different initial metallicity [M/H], helium mass fraction Y and mixing length parameter Lmix: mass (in solar mass), age (in Gyrs) effective temperature (in K), log of gravity (in cgs) and absolute magnitudes. The VRI magnitudes are in the Johnson-Cousins system and the JHK magnitudes in the CIT system. Note that the bolometric magnitude corresponds to M_bol(Sun)=4.64. The lowest mass corresponds to the hydrogen-burning limit.
3698. Low-mass stars evolutionary tracks & isochrones
ID:
ivo://CDS.VizieR/J/A+AS/141/371
Title:
Low-mass stars evolutionary tracks & isochrones
Short Name:
J/A+AS/141/371
Date:
21 Oct 2021
Publisher:
CDS
Description:
These files contain a large database of stellar models that are suitable to modelling star clusters and galaxies by means of population synthesis. They are based on a large grid of stellar evolutionary tracks for the initial chemical compositions [Z=0.0004, Y=0.23], [Z=0.001, Y=0.23], [Z=0.004, Y=0.24], [Z=0.008, Y=0.25], [Z=0.019, Y=0.273] (solar composition), and [Z=0.03, Y=0.30]. Tracks are computed with updated opacities and equation of state, and a moderate amount of convective overshoot. The range of initial masses goes from 0.15M_{sun}_ to 7M_{sun}_, and the evolutionary phases extend from the zero age main sequence (ZAMS) till either the thermally pulsing AGB regime or carbon ignition. We also present an additional set of models with solar composition, computed using the classical Schwarzschild's criterion for convective boundaries. From all these models, we derive: (1) Tables with the main quantities that characterize the stellar structure along the evolutionary tracks; (2) tables of surface chemical composition after the first and second dredge-up events; (3) extended theoretical isochrones in the Johnson-Cousins UBVRIJHK broad-band photometric system, together with summary tables; (4) integrated colours of single-burst stellar populations.
3699. Low-mass stars found in CFHTLS
ID:
ivo://CDS.VizieR/J/ApJ/633/630
Title:
Low-mass stars found in CFHTLS
Short Name:
J/ApJ/633/630
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present preliminary results of a new quasar survey being undertaken with multicolor optical imaging from the Canada-France-Hawaii Telescope. The current data consist of 3.83deg^2^ of imaging in the i' and z' filters to a 10{sigma} limit of z'<23.35. Near-infrared photometry of 24 candidate 5.7<z<6.4 quasars confirms them all to be low-mass stars, including two T dwarfs and four or five L dwarfs. Photometric estimates of the spectral type of the two T dwarfs are T3 and T6.
3700. Low-mass stars from the first two TESS sectors
ID:
ivo://CDS.VizieR/J/AJ/158/81
Title:
Low-mass stars from the first two TESS sectors
Short Name:
J/AJ/158/81
Date:
21 Oct 2021
Publisher:
CDS
Description:
Continuous data releases throughout the Transiting Exoplanet Survey Satellite (TESS) primary mission will provide unique opportunities for the exoplanet community at large to contribute to maximizing TESS's scientific return via the discovery and validation of transiting planets. This paper introduces our independent pipeline for the detection of periodic transit events along with the results of its inaugural application to the recently released 2 minute light curves of low-mass stars from the first two TESS sectors. The stellar parameters within our sample are refined using precise parallax measurements from the Gaia DR2 (Cat. I/345), which reduce the number of low-mass stars in our sample relative to those listed in the TESS Input Catalog. In lieu of the follow-up observations required to confirm or refute the planetary nature of transit-like signals, a validation of transit-like events flagged by our pipeline is performed statistically. The resulting vetted catalog contains eight probable blended eclipsing binaries, eight known TOIs, plus seven new planet candidates (PCs) smaller than 4 Earth radii. This work demonstrates the ability of our pipeline to detect sub-Neptune-sized PCs, which to date represent some of the most attractive targets for future atmospheric characterization via transmission or thermal emission spectroscopy and for radial velocity efforts aimed at the completion of the TESS level one requirement to deliver 50 planets smaller than 4 Earth radii with measured masses.