The Initial Mass Function Based on the Full-sky 20 pc Census of ∼3600 Stars and Brown Dwarfs

• DOI: 10.3847/1538-4365/ad24e2
• Publication Date: 2024-04-10T09:34:50Z
• Authors: J. Davy Kirkpatrick; Federico Marocco; Christopher R. Ge...; Yadukrishna Raghu; Jacqueline K. Fah...; Daniella C. Barda...; Steven D. Schurr; Kevin Apps; Adam C. Schneider; Aaron M. Meisner; Marc J. Kuchner; Dan Caselden; R. L. Smart; S. L. Casewell; Roberto Raddi; Aurora Kesseli; Nikolaj Stevnbak ...; Edoardo Antonini; Paul Beaulieu; Thomas P. Bickle; Martin Bilsing; Raymond Chieng; Guillaume Colin; Sam Deen; Alexandru Dereveanco; Katharina Doll; Hugo A. Durantini...; Anya Frazer; Jean Marc Gantier; Léopold Gramaize; Kristin Grant; Leslie K. Hamlet; Hiro 村 滉 Higashim...; Michiharu Hyogo; Peter A. Jałowiczor; Alexander Jonkeren; Martin Kabatnik; Frank Kiwy; David W. Martin; Marianne N. Michaels; William Pendrill; Celso Pessanha Ma...; Benjamin Pumphrey; Austin Rothermich; Rebekah Russwurm; Arttu Sainio; John Sanchez; Fyodor Theo Sapel...; Jörg Schümann; Karl Selg-Mann; Harshdeep Singh; Andres Stenner; Guoyou 国佑 Sun 孙; Christopher Tanner; Melina Thévenot; Maurizio Ventura; Nikita V. Voloshin; Jim Walla; Zbigniew Wędracki; Jose I. Adorno; Christian Aganze; Katelyn N. Allers; Hunter Brooks; Adam J. Burgasser; Emily Calamari; Thomas Connor; Edgardo Costa; Peter R. Eisenhardt; Jonathan Gagné; Roman Gerasimov; Eileen C. Gonzales; Chih-Chun Hsu; Rocio Kiman; Guodong Li; Ryan Low; Eric Mamajek; Blake M. Pantoja; Mark Popinchalk; Jon M. Rees; Daniel Stern; Genaro Suárez; Christopher Theissen; Chao-Wei Tsai; Johanna M. Vos; David Zurek
• Keywords: Initial mass function

Abstract A complete accounting of nearby objects—from the highest-mass white dwarf progenitors down to low-mass brown dwarfs—is now possible, thanks an almost set trigonometric parallax determinations from Gaia, ground-based surveys, and Spitzer follow-up. We create a census objects within Sun-centered sphere 20 pc radius check published literature decompose each binary or higher-order system into its separate components. The result is volume-limited ∼3600 individual star formation products useful in measuring initial mass function across stellar (&lt;8 M ⊙ ) substellar (≳5 Jup regimes. Comparing our resulting previous measurements shows good agreement above 0.8 divergence at lower masses. Our space densities are best fit with quadripartite power law, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>ξ</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:mi>M</mml:mi> stretchy="false">)</mml:mo> <mml:mo>=</mml:mo> <mml:mi mathvariant="italic">dN</mml:mi> <mml:mrow> stretchy="true">/</mml:mo> </mml:mrow> mathvariant="italic">dM</mml:mi> <mml:mo>∝</mml:mo> <mml:msup> <mml:mo>−</mml:mo> <mml:mi>α</mml:mi> </mml:msup> </mml:math> , long-established values α = 2.3 high masses (0.55 &lt; 8.00 ), 1.3 intermediate (0.22 0.55 but masses, we find 0.25 for 0.05 0.22 0.6 0.01 . This implies that rate production as decreasing diminishes star/high-mass regime before increasing again regime. Correcting completeness, number ratio of, currently, 4:1, average per object 0.41