- ID:
- ivo://CDS.VizieR/J/AJ/158/182
- Title:
- Discoveries from the NEOWISE proper motion survey
- Short Name:
- J/AJ/158/182
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present low-resolution near-infrared spectra of discoveries from an all-sky proper motion search conducted using multi-epoch data from the Wide-field Infrared Survey Explorer. Using the data from NEOWISE, along with the AllWISE catalog, Schneider et al. (2016, J/ApJ/817/112) conducted an all-sky proper motion survey to search for nearby objects with high proper motions. Here, we present a follow-up spectroscopic survey of 65 of their discoveries, which focused primarily on potentially nearby objects (d<25 pc), candidate late-type brown dwarfs (>=L7), and subdwarf candidates. We found 31 new M dwarfs, 18 new L dwarfs, and 11 new T dwarfs. Of these, 13 are subdwarfs, including one new sdL1 and two new sdL7s. Eleven of these discoveries, with spectral types ranging from M7 to T7 (including one subdwarf) are predicted to be within 25 pc, adding to the number of known objects in the solar neighborhood. We also discovered three new early-type T subdwarf candidates, one sdT1, one sdT2, and one sdT3, which would increase the number of known early-type T subdwarfs from two to five.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/501/785
- Title:
- Discovery and characterization of WASP-6b
- Short Name:
- J/A+A/501/785
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of WASP-6b, an inflated sub-Jupiter mass planet transiting every 3.3610060^+0.0000022^_-0.0000035_days a mildly metal-poor solar-type star of magnitude V=11.9. A combined analysis of the WASP photometry, high-precision followup transit photometry and radial velocities yield a planetary mass M_p_=0.503^+0.019^_-0.038_ and radius R_p_=1.224^+0.051^_0.052_, resulting in a density {rho}_p_=0.27{+/-}0.05{rho}_J_. The mass and radius for the host star are M_*_=0.88^+0.05^-0.08_M_{sun}_ and R_*_=0.870^0.025^_-0.036_R_{sun}_. The non-zero orbital eccentricity e=0.054^+0.018^_-0.015_ that we measure suggests that the planet underwent a massive tidal heating ~1Gyr ago that could have contributed to its inflated radius. High-precision radial velocities obtained during a transit allow us to measure a sky-projected angle between the stellar spin and orbital axis {beta}=11^+14^_-18_{deg}. In addition to similar published measurements, this result favors a dominant migration mechanism based on tidal interactions with a protoplanetary disk.
- ID:
- ivo://CDS.VizieR/J/ApJ/773/135
- Title:
- Disk-bearing stars in Cygnus OB2
- Short Name:
- J/ApJ/773/135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The formation of stars in massive clusters is one of the main modes of the star formation process. However, the study of massive star-forming regions is hampered by their typically large distances to the Sun. One exception to this is the massive star-forming region Cygnus OB2 in the Cygnus X region, at the distance of ~1400pc. Cygnus OB2 hosts very rich populations of massive and low-mass stars, being the best target in our Galaxy to study the formation of stars, circumstellar disks, and planets in the presence of massive stars. In this paper, we combine a wide and deep set of photometric data, from the r band to 24{mu}m, in order to select the disk-bearing population of stars in Cygnus OB2 and identify the class I, class II, and stars with transition and pre-transition disks. We selected 1843 sources with infrared excesses in an area of 1{deg}x1{deg} centered on Cyg OB2 in several evolutionary stages: 8.4% class I, 13.1% flat-spectrum sources, 72.9% class II, 2.3% pre-transition disks, and 3.3% transition disks. The spatial distribution of these sources shows a central cluster surrounded by an annular overdensity and some clumps of recent star formation in the outer region. Several candidate subclusters are identified, both along the overdensity and in the rest of the association.
- ID:
- ivo://CDS.VizieR/J/AJ/127/2085
- Title:
- Disk brightness profiles in galaxies
- Short Name:
- J/AJ/127/2085
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the disk brightness profiles of 218 spiral and lenticular galaxies. At least 28% of disk galaxies exhibit inner truncations in these profiles. There are no significant trends of truncation incidence with Hubble type, but the incidence among barred systems is 49%, more than 4 times that for non-barred galaxies. However, not all barred systems have inner truncations, and not all inner-truncated systems are currently barred. Truncations represent a real dearth of disk stars in the inner regions and are not an artifact of our selection or fitting procedures nor the result of obscuration by dust.
- ID:
- ivo://CDS.VizieR/J/A+A/592/A64
- Title:
- Disk galaxies at 0.1<z<1.0
- Short Name:
- J/A+A/592/A64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galaxy scaling relations such as the Tully-Fisher relation (between the maximum rotation velocity Vmax and luminosity) and the velocity-size relation (between Vmax and the disk scale length) are powerful tools to quantify the evolution of disk galaxies with cosmic time. We took spatially resolved slit spectra of 261 field disk galaxies at redshifts up to z~1 using the FORS instruments of the ESO Very Large Telescope. The targets were selected from the FORS Deep Field and William Herschel Deep Field. Our spectroscopy was complemented with HST/ACS imaging in the F814W filter. We analyzed the ionized gas kinematics by extracting rotation curves from the two-dimensional spectra. Taking into account all geometrical, observational, and instrumental effects, these rotation curves were used to derive the intrinsic V_max. Neglecting galaxies with disturbed kinematics or insufficient spatial rotation curve extent, Vmax was reliably determined for 124 galaxies covering redshifts 0.05<z<0.97. This is one of the largest kinematic samples of distant disk galaxies to date. We compared this data set to the local B-band Tully-Fisher relation and the local velocity-size relation. The scatter in both scaling relations is a factor of ~2 larger at z~0.5 than at z~0. The deviations of individual distant galaxies from the local Tully-Fisher relation are systematic in the sense that the galaxies are increasingly overluminous toward higher redshifts, corresponding to an overluminosity {Delta}M_B_=-(1.2+/-0.5) mag at z=1. This luminosity evolution at given Vmax is probably driven by younger stellar populations of distant galaxies with respect to their local counterparts, potentially combined with modest changes in dark matter mass fractions. The analysis of the velocity-size relation reveals that disk galaxies of a given Vmax have grown in size by a factor of ~1.5 over the past ~8Gyr, most likely through accretion of cold gas and/or small satellites. From scrutinizing the combined evolution in luminosity and size, we find that the galaxies that show the strongest evolution toward smaller sizes at z~1 are not those that feature the strongest evolution in luminosity, and vice versa.
- ID:
- ivo://CDS.VizieR/J/AJ/159/74
- Title:
- Disk-resolved photometric properties of Pluto
- Short Name:
- J/AJ/159/74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A multiwavelength regionally dependent photometric analysis of Pluto's anti-Charon-facing hemisphere using images collected by New Horizons' Multispectral Visible Imaging Camera (MVIC) reveals large variations in the absolute value and spectral slope of the single-scattering albedo. Four regions of interest are analyzed: the dark equatorial belt, Pluto's north pole, nitrogen-rich regions, and the mid-latitude terrains. Regions dominated by volatile ices such as Lowell Regio and Sputnik Planitia present single-scattering albedos of ~0.98 at 492nm, almost neutral across MVIC's visible wavelength range (400-910nm), indicating limited contributions from tholin materials. Pluto's dark equatorial regions, informally named Cthulhu and Krun Maculae, have single-scattering albedos of ~0.16 at 492nm and are the reddest regions. Applying the Hapke radiative transfer model to combined MVIC and Linear Etalon Imaging Spectral Array (LEISA) spectra (400-2500nm) of Cthulhu Macula and Lowell Regio successfully reproduces the spectral properties of these two regions of dramatically disparate coloration, composition, and morphology. Since this model uses only a single coloring agent, very similar to the Titan like tholin of Khare+ (1984Icar...60..127K), to account for all of Pluto's colors, this result supports the Grundy+ (2016Sci...351.9189G) conclusion that Pluto's coloration is the result of photochemical products mostly produced in the atmosphere. Although cosmic rays and extreme ultraviolet photons reach Pluto's surface where they can drive chemical processing, observations of diverse surface colors do not require different chemical products produced in different environments. We report a correction scaling factor in the LEISA radiometric calibration of 0.74{+/-}0.05.
- ID:
- ivo://CDS.VizieR/J/ApJ/688/362
- Title:
- Disks around brown dwarfs in {sigma} Ori cluster
- Short Name:
- J/ApJ/688/362
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed a census of circumstellar disks around brown dwarfs in the {sigma} Ori cluster using all available images from the Infrared Array Camera on board the Spitzer Space Telescope. To search for new low-mass cluster members with disks, we have measured photometry for all sources in the Spitzer images and have identified the ones that have red colors that are indicative of disks. We present five promising candidates, which may consist of two brown dwarfs, two stars with edge-on disks, and a low-mass protostar if they are bona fide members. Spectroscopy is needed to verify the nature of these sources. We have also used the Spitzer data to determine which of the previously known probable members of {sigma} Ori are likely to have disks. By doing so, we measure disk fractions of ~40% and ~60% for low-mass stars and brown dwarfs, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJ/717/L6
- Title:
- Displacement of black hole in M87
- Short Name:
- J/ApJ/717/L6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Isophotal analysis of M87, using data from the Advanced Camera for Surveys, reveals a projected displacement of 6.8+/-0.8pc (~0.1") between the nuclear point source (presumed to be the location of the supermassive black hole, SMBH) and the photo-center of the galaxy. The displacement is along a position angle of 307+/-17{deg} and is consistent with the jet axis. This suggests the active SMBH in M87 does not currently reside at the galaxy center of mass, but is displaced in the counter-jet direction. Possible explanations for the displacement include orbital motion of an SMBH binary, gravitational perturbations due to massive objects (e.g., globular clusters), acceleration by an asymmetric or intrinsically one-sided jet, and gravitational recoil resulting from the coalescence of an SMBH binary.
- ID:
- ivo://CDS.VizieR/J/A+A/550/A125
- Title:
- Distances and kinematics with CoRoT stars
- Short Name:
- J/A+A/550/A125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use kinematical and chemical properties of 754 CoRoT stars to characterise the stellar populations of the Milky Way disc in three beams close the Galactic plane. From the atmospheric parameters derived in Gazzano et al. (2010, Cat. J/A+A/523/A91) with the MATISSE algorithm, we derived stellar distances using isochrones. Combining these data with proper motions, we provide the complete kinematical description of stars in three CoRoT fields. Finally, we used kinematical criteria to identify the Galactic populations in our sample and study their characteristics, particularly their chemistry.
- ID:
- ivo://CDS.VizieR/J/A+A/446/515
- Title:
- Distances of nearby ultracool dwarfs
- Short Name:
- J/A+A/446/515
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present updated results of spectroscopic follow-up observations of a sample of 45 M dwarf candidates identified by Phan-Bao et al. (2003, Cat. <J/A+A/401/959>) based on the DENIS photometry and proper motion measurements. Forty one of these are nearby late-M dwarfs (d<30pc) with spectral types ranging from M5.0 to M8.5 computed from the spectral indices. One contaminant is probably an F-G main sequence star reddened by intervening dust and three stars that were not observed have previous classifications as M dwarfs in the literature. In this paper, we identify three M7.5, five M8.0, one M8.5 dwarf and confirm two new M8.0 dwarf members of the 25pc volume.
