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TOI 540 b: A Planet Smaller than Earth Orbiting a Nearby Rapidly Rotating Low-mass Star
DOI: 10.3847/1538-3881/abbd91 Bibcode: 2021AJ....161...23M

Latham, David W.; Ziegler, Carl; Vanderspek, Roland +20 more

We present the discovery of TOI 540 b, a hot planet slightly smaller than Earth orbiting the low-mass star 2MASS J05051443-4756154. The planet has an orbital period of P = 1.239149 days (±170 ms) and a radius of $r=0.903\pm 0.052{R}_{\oplus }$ , and is likely terrestrial based on the observed mass-radius distribution of small exoplanets at similar…

2021 The Astronomical Journal
Gaia XMM-Newton 24
ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): Detection of Extremely High-density Compact Structure of Prestellar Cores and Multiple Substructures Within
DOI: 10.3847/2041-8213/abd3aa Bibcode: 2021ApJ...907L..15S

Sanhueza, Patricio; Kwon, Woojin; Soam, Archana +38 more

Prestellar cores are self-gravitating dense and cold structures within molecular clouds where future stars are born. They are expected, at the stage of transitioning to the protostellar phase, to harbor centrally concentrated dense (sub)structures that will seed the formation of a new star or the binary/multiple stellar systems. Characterizing thi…

2021 The Astrophysical Journal
Herschel 24
Characterization of the Candidate Landing Region for Tianwen-1—China's First Mission to Mars
DOI: 10.1029/2021EA001670 Bibcode: 2021E&SS....801670W

Liu, Wai Chung; Wu, Bo; Li, Yuan +7 more

This paper presents our efforts to characterize the candidate landing region (109°-133°E, 23°-30°N) for Tianwen-1, China's first mission to Mars, in terms of engineering safety and scientific significance. Topographic analysis reveals that the region has a low elevation around −4,230 m, and 98% of the region have slopes smaller than 8°. The geomor…

2021 Earth and Space Science
MEx 24
An ALMA Gas-dynamical Mass Measurement of the Supermassive Black Hole in the Local Compact Galaxy UGC 2698
DOI: 10.3847/1538-4357/ac0f78 Bibcode: 2021ApJ...919...77C

Ho, Luis C.; Gebhardt, Karl; Barth, Aaron J. +9 more

We present 0"14 resolution Atacama Large Millimeter/submillimeter Array (ALMA) CO(2-1) observations of the circumnuclear gas disk in UGC 2698, a local compact galaxy. The disk exhibits regular rotation with projected velocities rising to 450 km s-1 near the galaxy center. We fit gas-dynamical models to the ALMA data cube, assuming the C…

2021 The Astrophysical Journal
eHST 24
A Multiwavelength Look at the GJ 9827 System: No Evidence of Extended Atmospheres in GJ 9827b and d from HST and CARMENES Data
DOI: 10.3847/1538-3881/abdb2f Bibcode: 2021AJ....161..136C

Ayres, Thomas R.; Redfield, Seth; Youngblood, Allison +18 more

GJ 9827 is a bright star hosting a planetary system with three transiting planets. As a multiplanet system with planets that sprawl within the boundaries of the radius gap between terrestrial and gaseous planets, GJ 9827 is an optimal target to study the evolution of the atmospheres of close-in planets with a common evolutionary history and their …

2021 The Astronomical Journal
eHST 24
Scaling K2. IV. A Uniform Planet Sample for Campaigns 1-8 and 10-18
DOI: 10.3847/1538-3881/ac2309 Bibcode: 2021AJ....162..259Z

Schlieder, Joshua E.; Petigura, Erik A.; Crossfield, Ian J. M. +6 more

We provide the first full K2 transiting exoplanet sample, using photometry from Campaigns 1-8 and 10-18, derived through an entirely automated procedure. This homogeneous planet candidate catalog is crucial to perform a robust demographic analysis of transiting exoplanets with K2. We identify 747 unique planet candidates and 57 multiplanet systems…

2021 The Astronomical Journal
Gaia 24
Sunspot tilt angles revisited: Dependence on the solar cycle strength
DOI: 10.1051/0004-6361/202141215 Bibcode: 2021A&A...653A..27J

Jiang, Jie; Jiao, Qirong; Wang, Zi-Fan

Context. The tilt angle of sunspot groups is crucial in the Babcock-Leighton (BL) type dynamo for the generation of the poloidal magnetic field. Some studies have shown that the tilt coefficient, which excludes the latitudinal dependence of the tilt angles, is anti-correlated with the cycle strength. If the anti-correlation exists, it will be show…

2021 Astronomy and Astrophysics
SOHO 24
The Cosmic Ultraviolet Baryon Survey (CUBS) - IV. The complex multiphase circumgalactic medium as revealed by partial Lyman limit systems
DOI: 10.1093/mnras/stab2869 Bibcode: 2021MNRAS.508.4359C

Faucher-Giguère, Claude-André; Johnson, Sean D.; Petitjean, Patrick +18 more

We present a detailed study of two partial Lyman limit systems (pLLSs) of neutral hydrogen column density $N_\mathrm{H\, I}\approx (1-3)\times 10^{16}\, \mathrm{cm}^{-2}$ discovered at $z$ = 0.5 in the Cosmic Ultraviolet Baryon Survey (CUBS). Available far-ultraviolet spectra from the Hubble Space Telescope Cosmic Origins Spectrograph and optical …

2021 Monthly Notices of the Royal Astronomical Society
eHST 24
Which Milky Way masses are consistent with the slightly declining 5-25 kpc rotation curve?
DOI: 10.1051/0004-6361/202141058 Bibcode: 2021A&A...654A..25J

Hammer, F.; Jiao, Y.; Wang, J. L. +1 more

Context. Discoveries of extended rotation curves have suggested that spiral galaxy halos contain dark matter. This has led to many studies that estimated the total mass of the Galaxy, mostly using the Navarro, Frenk, and White (NFW) density profile.
Aims: We determine the effect that the choice of the dark matter profile has on the predicted …

2021 Astronomy and Astrophysics
Gaia 24
Testing Primordial Black Holes with multi-band observations of the stochastic gravitational wave background
DOI: 10.1088/1475-7516/2021/12/012 Bibcode: 2021JCAP...12..012B

García-Bellido, Juan; Kuroyanagi, Sachiko; Braglia, Matteo

The mass distribution of Primordial Black Holes (PBHs) is affected by drops in the pressure of the early Universe plasma. For example, events in the standard model of particle physics, such as the W ±/Z 0 decoupling, the quark-hadron transition, the muon and pion becoming non-relativistic, and the annihilation of electrons an…

2021 Journal of Cosmology and Astroparticle Physics
Gaia 24