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Journal articles on the topic 'Low mass companions'

Author: Grafiati

Published: 4 May 2024

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1

Evans, Nancy Remage, Scott Engle, Ignazio Pillitteri, Edward Guinan, H. Moritz Günther, Scott Wolk, Hilding Neilson, et al. "X-Rays in Cepheids: Identifying Low-mass Companions of Intermediate-mass Stars*." Astrophysical Journal 938, no. 2 (October 1, 2022): 153. http://dx.doi.org/10.3847/1538-4357/ac6fdf.

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Abstract X-ray observations have been made of a sample of 20 classical Cepheids, including two new observations (Polaris and l Car) reported here. The occurrence of X-ray flux around the pulsation cycle is discussed. Three Cepheids are detected (δ Cep, β Dor, and Polaris). X-rays have also been detected from the low-mass F, G, and K companions of four Cepheids (V473 Lyr, R Cru, V659 Cen, and W Sgr) and one hot companion (S Mus). Upper limits on the X-ray flux of the remaining Cepheids provide an estimate that 28% have low-mass companions. This fraction of low-mass companions in intermediate-mass Cepheids is significantly lower than expected from random pairing with the field initial mass function (IMF). Combining the companion fraction from X-rays with that from ultraviolet observations results in a binary/multiple fraction of 57% ± 12% for Cepheids with ratios q > 0.1 and separations a >1 au. This is a lower limit since M stars are not included. X-ray observations detect less massive companions than other existing studies of intermediate-mass stars. Our measured occurrence rate of unresolved, low-mass companions to Cepheids suggests that intermediate-period binaries derive from a combination of disk and core fragmentation and accretion. This yields a hybrid mass ratio distribution that is skewed toward small values compared to a uniform distribution but is still top-heavy compared to random pairings drawn from the IMF.

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2

Scott Gaudi, B. "Microlensing Constraints on Low-Mass Companions." Symposium - International Astronomical Union 211 (2003): 305–8. http://dx.doi.org/10.1017/s0074180900210826.

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Microlensing is sensitive to binary, brown dwarf (BD), and planetary companions to normal stars in the Galactic bulge with separations between about 1–10 AU. The accurate, densely-sampled photometry of microlensing events needed to detect planetary companions has been achieved by several follow-up collaborations. Detailed analysis of microlensing events toward the bulge demonstrates that less than 45% of M-dwarfs in the bulge have MJup companions between 1 and 5 AU. Detection of binary and BD companions using microlensing is considerably easier; however, the interpretation is hampered by their non-perturbative influence on the parent lightcurve. I demonstrate that ~ 25% of BD companions with separations 1 – 10AU should be detectable with survey-quality data (~ 1 day sampling and ~ 5% photometry). Survey data is more amenable to generic, brute-force analysis methods and less prone to selection biases. An analysis of the ~ 1500 microlensing events detected by OGLE-III in the next three years should test whether the BD desert exists at separations 1 – 10AU from M-dwarfs in the Galactic bulge.

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3

Naef, D., M. Mayor, D. Queloz, S. Udry, F. Arenou, J. L. Beuzit, C. Perrier-Bellet, and J. P. Sivan. "ELODIE low-mass companions to solar-type stars." Symposium - International Astronomical Union 202 (2004): 96–98. http://dx.doi.org/10.1017/s0074180900217580.

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We present radial-velocity measurements for three solar-type stars (HD 127506, HD 174457 and HD 185414) hosting low-mass companions. The measurements were obtained with the ELODIE echelle spectrograph mounted on the 1.93–m telescope at Observatoire de Haute–Provence (CNRS, France) within the frame of the OHP-ELODIE Planet Search Programme. The inferred minimum masses of the detected companions are in the substellar mass range. Combining ELODIE radial-velocity data and HIPPARCOS astrometric data, the inclination angles of the orbital planes of HD 127506 and HD 174457 have been derived providing us with the de-projected masses of the companions: m2 = 44MJup for the companion of HD 127506 and m2= 0.13M⊙ for the companion of HD 174457. Moreover, using adaptive optics measurements, we show that HD 174457 is probably a (F8V + M7V + M3-4V) triple system. To date, only a minimal orbital solution is available for HD 185414.

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4

Guenther, E. W., D. B. Paulson, W. D. Cochran, J. Patience, A. P. Hatzes, and B. Macintosh. "Low-mass companions to Hyades stars." Astronomy & Astrophysics 442, no. 3 (October 14, 2005): 1031–39. http://dx.doi.org/10.1051/0004-6361:20052851.

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5

Farihi, J., B. Zuckerman, and E. E. Becklin. "Low mass companions to white dwarfs." Astronomische Nachrichten 326, no. 10 (December 2005): 964–68. http://dx.doi.org/10.1002/asna.200510434.

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6

Ginzburg, Sivan, and Eliot Quataert. "Black widow formation by pulsar irradiation and sustained magnetic braking." Monthly Notices of the Royal Astronomical Society 500, no. 2 (October 29, 2020): 1592–603. http://dx.doi.org/10.1093/mnras/staa3358.

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ABSTRACT Black widows are millisecond pulsars with low-mass companions, a few per cent the mass of the sun, on orbits of several hours. These companions are presumably the remnants of main-sequence stars that lost their mass through a combination of Roche lobe overflow and ablation by the host pulsar’s high-energy radiation. While ablation itself is too weak to significantly reduce the mass of the companion star, the ablated wind couples to its magnetic field, removes orbital angular momentum, and thus maintains stable Roche lobe overflow. We use the mesa stellar evolution code, complemented by analytical estimates, to track initially main-sequence companions as they are reduced to a fraction of their original mass by this ablation-driven magnetic braking. We argue that magnetic braking remains effective even for low-mass companions. A key ingredient of our model is that the irradiating luminosity of the pulsar Lirr deposits energy in the companion’s atmosphere and thereby slows down its Kelvin–Helmholtz cooling. We find that the high-energy luminosities measured by Fermi $L_{\rm irr}=0.1\rm {-}3$ L⊙ can explain the span of black widow orbital periods. The same Lirr range reproduces the companions’ night-side temperatures, which cluster around 3000 K, as inferred from optical light curves.

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7

Jódar, Esther, Antonio Pérez-Garrido, Anastasio Díaz-Sánchez, Isidro Villó, Rafael Rebolo, and Jorge A. Pérez-Prieto. "New companions to nearby low-mass stars." Monthly Notices of the Royal Astronomical Society 429, no. 1 (December 10, 2012): 859–67. http://dx.doi.org/10.1093/mnras/sts382.

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8

Wolf, M., P. Zasche, H. Kučáková, J. Vraštil, K. Hornoch, L. Šmelcer, F. Bílek, L. Pilarčík, and M. Chrastina. "Substellar companions in low-mass eclipsing binaries." Astronomy & Astrophysics 587 (February 22, 2016): A82. http://dx.doi.org/10.1051/0004-6361/201527941.

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9

Andrews, Jeff J., Adrian M. Price-Whelan, and Marcel A. Agüeros. "THE MASS DISTRIBUTION OF COMPANIONS TO LOW-MASS WHITE DWARFS." Astrophysical Journal 797, no. 2 (December 9, 2014): L32. http://dx.doi.org/10.1088/2041-8205/797/2/l32.

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10

Zhou, Yifan, Gregory J. Herczeg, Adam L. Kraus, Stanimir Metchev, and Kelle L. Cruz. "ACCRETION ONTO PLANETARY MASS COMPANIONS OF LOW-MASS YOUNG STARS." Astrophysical Journal 783, no. 1 (February 18, 2014): L17. http://dx.doi.org/10.1088/2041-8205/783/1/l17.

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11

Zinnecker, H. "Observations of low mass companions to massive stars." Proceedings of the International Astronomical Union 5, H15 (November 2009): 760. http://dx.doi.org/10.1017/s1743921310011440.

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Massive stars are known to be multiple systems, often in tight, short-period OB stars binaries (SB1 and SB2, found by spectroscopic monitoring). However, little is known about low-mass companions to massive stars, such as A, F, and G stars with masses in the range of 1 to 3 solar masses. Yet systems of massive stars with wide low-mass companions (of the order of a few AU) must exist, for these are the progenitors of LMXB and HMXB (low-mass and high-mass X-ray binaries).

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12

Kostogryz, N., M. Kürster, T. Yakobchuk, Y. Lyubchik, and M. Kuznetsov. "A spectral differential characterization of low-mass companions." EPJ Web of Conferences 47 (2013): 13003. http://dx.doi.org/10.1051/epjconf/20134713003.

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13

Evans, Nancy Remage, Edward Guinan, Scott Engle, Scott J. Wolk, Eric Schlegel, Brian D. Mason, Margarita Karovska, and Bradley Spitzbart. "CHANDRAOBSERVATION OF POLARIS: CENSUS OF LOW-MASS COMPANIONS." Astronomical Journal 139, no. 5 (April 8, 2010): 1968–74. http://dx.doi.org/10.1088/0004-6256/139/5/1968.

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14

Tokovinin, Andrei. "LOW-MASS VISUAL COMPANIONS TO NEARBY G-DWARFS." Astronomical Journal 141, no. 2 (January 13, 2011): 52. http://dx.doi.org/10.1088/0004-6256/141/2/52.

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15

King, A. R., J. Frank, U. Kolb, and H. Ritter. "Transients among Binaries with Evolved Low‐Mass Companions." Astrophysical Journal 484, no. 2 (August 1997): 844–47. http://dx.doi.org/10.1086/304383.

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16

Yılmaz, M., I. Bikmaev, B. Sato, S. O. Selam, A. I. Galeev, V. Keskin, H. Izumiura, et al. "Low mass stellar companions around four giant stars." New Astronomy 34 (January 2015): 108–13. http://dx.doi.org/10.1016/j.newast.2014.06.005.

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17

Latham, David W., Robert P. Stefanik, and Tsevi Mazeh. "Spectroscopic searches for low-mass companions of stars." Acta Astronautica 26, no. 3-4 (March 1992): 145–49. http://dx.doi.org/10.1016/0094-5765(92)90086-x.

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18

Baum, William A. "Searching for Low–Mass Companions with the HST WF/PC." International Astronomical Union Colloquium 135 (1992): 365–68. http://dx.doi.org/10.1017/s0252921100006813.

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AbstractOwing to the spherical aberration of the Hubble Space Telescope, prospects are now poor for the astrometric detection of low–mass companions of nearby stars with the Wide–Field / Planetary Camera. The installation of a new camera (WF/PC-II) incorporating an optical correction for the telescope will only partially recover the low–mass companion search capability.

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19

Suárez-Andrés, L., G. Israelian, J. I. González Hernández, V. Zh Adibekyan, E. Delgado Mena, N. C. Santos, and S. G. Sousa. "C/O vs. Mg/Si ratios in solar type stars: The HARPS sample." Astronomy & Astrophysics 614 (June 2018): A84. http://dx.doi.org/10.1051/0004-6361/201730743.

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Context. Aims. We aim to present a detailed study of the magnesium-to-silicon and carbon-to-oxygen ratios (Mg/Si and C/O) and their importance in determining the mineralogy of planetary companions. Methods. Using 499 solar-like stars from the HARPS sample, we determined C/O and Mg/Si elemental abundance ratios to study the nature of the possible planets formed. We separated the planetary population in low-mass planets (<30 M⊙) and high-mass planets (>30 M⊙) to test for a possible relation with the mass. Results. We find a diversity of mineralogical ratios that reveal the different kinds of planetary systems that can be formed, most of them dissimilar to our solar system. The different values of the Mg/Si and C/O can determine different composition of planets formed. We found that 100% of our planetary sample present C/O < 0.8. 86% of stars with high-mass companions present 0.8 > C/O > 0.4, while 14% present C/O values lower than 0.4. Regarding Mg/Si, all stars with low-mass planetary companion showed values between one and two, while 85% of the high-mass companion sample does. The other 15% showed Mg/Si values below one. No stars with planets were found with Mg/Si > 2. Planet hosts with low-mass companions present C/O and Mg/Si similar to those found in the Sun, whereas stars with high-mass companions have lower C/O.

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20

Roberts, Mallory S. E. "Surrounded by spiders! New black widows and redbacks in the Galactic field." Proceedings of the International Astronomical Union 8, S291 (August 2012): 127–32. http://dx.doi.org/10.1017/s174392131202337x.

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AbstractOver the last few years, the number of known eclipsing radio millisecond pulsar systems in the Galactic field has dramatically increased, with many being associated with Fermi gamma-ray sources. All are in tight binaries (orbital period < 24 hr) with many being classical “black widows” which have very low mass companions (companion mass Mc ≪ 0.1 M⊙) but some are “redbacks” with low mass (Mc ~ 0.2-0.4 M⊙) companions which are probably non-degenerate. These latter are systems where the mass transfer process may have only temporarily halted, and so are transitional systems between low mass X-ray binaries and ordinary binary millisecond pulsars. Here we review the new discoveries and their multi-wavelength properties, and briefly discuss models of shock emission, mass determinations, and evolutionary scenarios.

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21

HUANG, XINYUE. "Mass and orbital solutions of stellar companions from HGCA and lick." Theoretical and Natural Science 13, no. 1 (November 30, 2023): 215–25. http://dx.doi.org/10.54254/2753-8818/13/20240850.

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Astrometry or radial velocity method, as an exoplanet detection and characterisation method, needs more information to reveal the complete orbit solution of stellar companions. We combine these two methods by cross-calibrating the Hipparcos-Gaia Catalogue of Accelerating Stars and Lick data to generate more precise mass and orbital solutions of stellar companions from the overlap of these two databases. We use an open-source package, orvara, to simulate the posterior parameters of companions from candidate stars. To simplify the simulation, we assume all systems in this research contain only a 2-body Keplerian fit. A final result of 16 candidates is selected, and five companions with the lowest masses are further discussed. Among these five companions, four in system HIP42112, HIP49699, HIP74948 and HIP98819 were discovered and recorded in previous work. This paper has found an undiscovered potential brown dwarf companion near HIP98978. The result of this paper could help future studies of low-mass companions of exoplanets.

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22

Klement, Robert, Thomas Rivinius, Douglas R. Gies, Dietrich Baade, Antoine Mérand, John D. Monnier, Gail H. Schaefer, et al. "The CHARA Array Interferometric Program on the Multiplicity of Classical Be Stars: New Detections and Orbits of Stripped Subdwarf Companions." Astrophysical Journal 962, no. 1 (February 1, 2024): 70. http://dx.doi.org/10.3847/1538-4357/ad13ec.

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Abstract Rapid rotation and nonradial pulsations enable Be stars to build decretion disks, where the characteristic line emission forms. A major but unconstrained fraction of Be stars owe their rapid rotation to mass and angular momentum transfer in a binary. The faint, stripped companions can be helium-burning subdwarf OB-type stars (sdOBs), white dwarfs (WDs), or neutron stars. We present optical/near-infrared Center for High Angular Resolution Astronomy (CHARA) interferometry of 37 Be stars selected for spectroscopic indications of low-mass companions. From multiepoch H- and/or K-band interferometry plus radial velocities and parallaxes collected elsewhere, we constructed 3D orbits and derived flux ratios and absolute dynamical masses of both components for six objects, quadrupling the number of anchor points for evolutionary models. In addition, a new wider companion was identified for the known Be + sdO binary 59 Cyg, while auxiliary Very Large Telescope Interferometer/GRAVITY spectrointerferometry confirmed circumstellar matter around the sdO companion to HR 2142. On the other hand, we failed to detect any companion to the six Be stars with γ Cas–like X-ray emission, with sdOB and main-sequence companions of the expected spectroscopic mass being ruled out for the X-ray-prototypical stars γ Cas and π Aqr, leaving elusive WDs as the most likely companions, as well as a likely explanation of the X-rays. No low-mass main-sequence close companions were identified for the other stars.

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23

Bohn, Alexander J., Christian Ginski, Matthew A. Kenworthy, Eric E. Mamajek, Tiffany Meshkat, Mark J. Pecaut, Maddalena Reggiani, et al. "Unveiling wide-orbit companions to K-type stars in Sco-Cen with Gaia EDR3." Astronomy & Astrophysics 657 (January 2022): A53. http://dx.doi.org/10.1051/0004-6361/202039917.

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Context. The detection of low-mass companions to stellar hosts is important for testing the formation scenarios of these systems. Companions at wide separations are particularly intriguing objects as they are easily accessible for variability studies of the rotational dynamics and cloud coverage of these brown dwarfs or planetary-mass objects. Aims. We aim to identify new low-mass companions to young stars using the astrometric measurements provided by the Gaia space mission. When possible, we use high-contrast imaging data collected with VLT/SPHERE. Methods. We identified companion candidates from a sample of K-type, pre-main-sequence stars in the Scorpius Centaurus association using the early version of the third data release of the Gaia space mission. Based on the provided positions, proper motions, and magnitudes, we identified all objects within a predefined radius, whose differential proper motions are consistent with a gravitationally bound system. As the ages of our systems are known, we derived companion masses through comparison with evolutionary tracks. For seven identified companion candidates we used additional data collected with VLT/SPHERE and VLT/NACO to assess the accuracy of the properties of the companions based on Gaia photometry alone. Results. We identify 110 comoving companions that have a companionship likelihood of more than 95%. Further color-magnitude analysis confirms their Sco-Cen membership. We identify ten especially intriguing companions that have masses in the brown dwarf regime down to 20 MJup. Our high-contrast imaging data confirm both astrometry and photometric masses derived from Gaia alone. We discovered a new brown dwarf companion, TYC 8252-533-1 B, with a projected separation of approximately 570 au from its Sun-like primary. It is likely to be located outside the debris disk around its primary star and SED modeling of Gaia, SPHERE, and NACO photometry provides a companion mass of 52−11+17 MJup. Conclusions. We show that the Gaia database can identify low-mass companions at wide separations from their host stars. For K-type Sco-Cen members, Gaia can detect sub-stellar objects at projected separations larger than 300 au and with a sensitivity limit beyond 1000 au and a lower mass limit down to 20 MJup. A similar analysis of other star-forming regions could significantly enlarge the sample size of such objects and facilitate testing of the formation and evolution theories of planetary systems.

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Bohn, Alexander J., Christian Ginski, Matthew A. Kenworthy, Eric E. Mamajek, Tiffany Meshkat, Mark J. Pecaut, Maddalena Reggiani, et al. "Unveiling wide-orbit companions to K-type stars in Sco-Cen with Gaia EDR3." Astronomy & Astrophysics 657 (January 2022): A53. http://dx.doi.org/10.1051/0004-6361/202039917.

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Context. The detection of low-mass companions to stellar hosts is important for testing the formation scenarios of these systems. Companions at wide separations are particularly intriguing objects as they are easily accessible for variability studies of the rotational dynamics and cloud coverage of these brown dwarfs or planetary-mass objects. Aims. We aim to identify new low-mass companions to young stars using the astrometric measurements provided by the Gaia space mission. When possible, we use high-contrast imaging data collected with VLT/SPHERE. Methods. We identified companion candidates from a sample of K-type, pre-main-sequence stars in the Scorpius Centaurus association using the early version of the third data release of the Gaia space mission. Based on the provided positions, proper motions, and magnitudes, we identified all objects within a predefined radius, whose differential proper motions are consistent with a gravitationally bound system. As the ages of our systems are known, we derived companion masses through comparison with evolutionary tracks. For seven identified companion candidates we used additional data collected with VLT/SPHERE and VLT/NACO to assess the accuracy of the properties of the companions based on Gaia photometry alone. Results. We identify 110 comoving companions that have a companionship likelihood of more than 95%. Further color-magnitude analysis confirms their Sco-Cen membership. We identify ten especially intriguing companions that have masses in the brown dwarf regime down to 20 MJup. Our high-contrast imaging data confirm both astrometry and photometric masses derived from Gaia alone. We discovered a new brown dwarf companion, TYC 8252-533-1 B, with a projected separation of approximately 570 au from its Sun-like primary. It is likely to be located outside the debris disk around its primary star and SED modeling of Gaia, SPHERE, and NACO photometry provides a companion mass of 52−11+17 MJup. Conclusions. We show that the Gaia database can identify low-mass companions at wide separations from their host stars. For K-type Sco-Cen members, Gaia can detect sub-stellar objects at projected separations larger than 300 au and with a sensitivity limit beyond 1000 au and a lower mass limit down to 20 MJup. A similar analysis of other star-forming regions could significantly enlarge the sample size of such objects and facilitate testing of the formation and evolution theories of planetary systems.

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25

Allen, P. R., D. W. Koerner, M. W. McElwain, G. R. Murphy, I. Neill Reid, J. E. Gizis, and J. Davy Kirkpatrick. "A Search for Companions to L Dwarfs." Symposium - International Astronomical Union 211 (2003): 303–4. http://dx.doi.org/10.1017/s0074180900210814.

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We present the results of two imaging surveys for companions to low-luminosity dwarfs, one with Keck to a limiting magnitude of K = 20, and the other with HST to a limiting magnitude of I = 23. No companions were found at separations of 0″.5 to 20″.0, but seven companions were found within 0″.5. Based on sub-stellar evolutionary models, we estimate the companion detection efficiency as a function of mass ratio. This modeling, coupled with the data, place strong upper limits on the mass ratios of unobserved companions. We conclude that no companions exist in the optimal sensitivity regions of both surveys for q > 0.85 (HST), and q > 0.4 (Keck).

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Beuzit, J. L., G. Chauvin, X. Delfosse, T. Forveille, A. M. Lagrange, L. Marchal, M. Mayor, et al. "Low mass companions searches using high dynamic range imaging." EAS Publications Series 12 (2004): 319–36. http://dx.doi.org/10.1051/eas:2004046.

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Kilic, Mukremin, Warren R. Brown, and B. McLeod. "ASPITZERSEARCH FOR SUBSTELLAR COMPANIONS TO LOW-MASS WHITE DWARFS." Astrophysical Journal 708, no. 1 (December 11, 2009): 411–18. http://dx.doi.org/10.1088/0004-637x/708/1/411.

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Marcy, Geoffrey W., and Karsten J. Benitz. "A search for substellar companions to low-mass stars." Astrophysical Journal 344 (September 1989): 441. http://dx.doi.org/10.1086/167812.

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De Furio, Matthew, Christopher Liu, Michael R. Meyer, Megan Reiter, Adam Kraus, Trent Dupuy, and John Monnier. "Demographics of the M-star Multiple Population in the Orion Nebula Cluster." Astrophysical Journal 941, no. 2 (December 1, 2022): 161. http://dx.doi.org/10.3847/1538-4357/aca285.

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Abstract We present updated results constraining multiplicity demographics for the stellar population of the Orion Nebula Cluster (ONC, a high-mass, high-density star-forming region), across primary masses 0.08–0.7 M ⊙. Our study utilizes archival Hubble Space Telescope data obtained with the Advanced Camera for Surveys using multiple filters (GO-10246). Previous multiplicity surveys in low-mass, low-density associations like Taurus identify an excess of companions to low-mass stars roughly twice that of the Galactic field and find the mass ratio distribution consistent with the field. Previously, we found the companion frequency to low-mass stars in the ONC is consistent with the Galactic field over mass ratios = 0.6–1.0 and projected separations = 30–160 au, without placing constraints on the mass ratio distribution. In this study, we investigate the companion population of the ONC with a double point-spread function (PSF) fitting algorithm sensitive to separations larger than 10 au (0.″025) using empirical PSF models. We identified 44 companions (14 new), and with a Bayesian analysis we estimate the companion frequency to low-mass stars in the ONC = 0.13 − 0.03 + 0.05 and the index of the power-law fit to the mass ratio distribution = 2.08 − 0.85 + 1.03 over all mass ratios and projected separations of 10–200 au. We find the companion frequency in the ONC is consistent with the Galactic field population, likely from states of high transient stellar density, and a probability of 0.002 that it is consistent with that of Taurus. We also find the ONC mass ratio distribution is consistent with the field and Taurus, potentially indicative of its primordial nature, a direct outcome of the star formation process.

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Lepp, Stephen, Rebecca G. Martin, and Bing Zhang. "Black Hole Mergers Driven by a Captured Low-mass Companion." Astrophysical Journal Letters 958, no. 2 (November 24, 2023): L23. http://dx.doi.org/10.3847/2041-8213/ad0bd8.

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Abstract Increased eccentricity of a black hole binary leads to reduced merger times. With n-body simulations and analytic approximations including the effects of general relativity (GR), we show that even a low-mass companion orbiting a black hole binary can cause significant eccentricity oscillations of the binary as a result of the Kozai–Lidov mechanism. A companion with a mass as low as about 1% of the binary mass can drive the binary eccentricity up to ≳0.8, while a mass of a few percent can drive eccentricities greater than 0.98. For low-mass companions, this mechanism requires the companion to be on an orbit that is closer to retrograde than to prograde to the binary orbit, and this may occur through capture of the third body. The effects of GR limit the radial range for the companion for which this mechanism works for the closest binaries. The merger timescale may be reduced by several orders of magnitude for a captured companion mass of only a few percent of the binary mass.

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Suess, Katherine A., Christina C. Williams, Brant Robertson, Zhiyuan Ji, Benjamin D. Johnson, Erica Nelson, Stacey Alberts, et al. "Minor Merger Growth in Action: JWST Detects Faint Blue Companions around Massive Quiescent Galaxies at 0.5 ≤ z ≤ 3.0." Astrophysical Journal Letters 956, no. 2 (October 1, 2023): L42. http://dx.doi.org/10.3847/2041-8213/acf5e6.

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Abstract Minor mergers are thought to drive the structural evolution of massive quiescent galaxies; however, existing Hubble Space Telescope (HST) imaging is primarily sensitive to stellar mass ratios ≳1:10. Here, we report the discovery of a large population of low-mass companions within 35 kpc of known log M * / M ⊙ ≳ 10.5 quiescent galaxies at 0.5 ≤ z ≤ 3. While massive companions like those identified by HST are rare, JWST imaging from the JWST Advanced Deep Extragalactic Survey reveals that the average massive quiescent galaxy hosts approximately five nearby companions with stellar mass ratios <1:10. Despite a median stellar mass ratio of just 1:900, these tiny companions are so numerous that they represent at least 30% of the total mass being added to quiescent galaxies via minor mergers. While relatively massive companions have colors similar to their hosts, companions with mass ratios <1:10 typically have bluer colors and lower mass-to-light ratios than their host galaxies at similar radii. The accretion of these tiny companions is likely to drive evolution in the color gradients and stellar population properties of the host galaxies. Our results suggest that the well-established “minor merger growth” model for quiescent galaxies extends down to very low mass ratios of ≲1:100, and demonstrates the power of JWST to constrain both the spatially resolved properties of massive galaxies and the properties of low-mass companions beyond the local Universe.

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Janson, Markus, Ruben Asensio-Torres, Damien André, Mickaël Bonnefoy, Philippe Delorme, Sabine Reffert, Silvano Desidera, et al. "The B-Star Exoplanet Abundance Study: a co-moving 16–25 MJup companion to the young binary system HIP 79098." Astronomy & Astrophysics 626 (June 2019): A99. http://dx.doi.org/10.1051/0004-6361/201935687.

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Wide low-mass substellar companions are known to be very rare among low-mass stars, but appear to become increasingly common with increasing stellar mass. However, B-type stars, which are the most massive stars within ~150 pc of the Sun, have not yet been examined to the same extent as AFGKM-type stars in that regard. In order to address this issue, we launched the ongoing B-star Exoplanet Abundance Study (BEAST) to examine the frequency and properties of planets, brown dwarfs, and disks around B-type stars in the Scorpius-Centaurus (Sco-Cen) association; we also analyzed archival data of B-type stars in Sco-Cen. During this process, we identified a candidate substellar companion to the B9-type spectroscopic binary HIP 79098 AB, which we refer to as HIP 79098 (AB)b. The candidate had been previously reported in the literature, but was classified as a background contaminant on the basis of its peculiar colors. Here we demonstrate that the colors of HIP 79098 (AB)b are consistent with several recently discovered young and low-mass brown dwarfs, including other companions to stars in Sco-Cen. Furthermore, we show unambiguous common proper motion over a 15-yr baseline, robustly identifying HIP 79098 (AB)b as a bona fide substellar circumbinary companion at a 345 ± 6 AU projected separation to the B9-type stellar pair. With a model-dependent mass of 16–25 MJup yielding a mass ratio of <1%, HIP 79098 (AB)b joins a growing number of substellar companions with planet-like mass ratios around massive stars. Our observations underline the importance of common proper motion analysis in the identification of physical companionship, and imply that additional companions could potentially remain hidden in the archives of purely photometric surveys.

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Evans, Nancy Remage. "Cepheid Binaries: Frequency and Mass Ratios." International Astronomical Union Colloquium 155 (1995): 252–53. http://dx.doi.org/10.1017/s0252921100037040.

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AbstractUltraviolet spectroscopy with the IUE satellite has been used to survey all Cepheids brighter than 8th magnitude to identify blue companions. The derived binary frequency is 21% with blue companions which implies that 34% would have been found from a large radial velocity survey. A second study has used deep IUE exposures of Cepheids showing orbital motion to determine the distribution of mass ratios in Cepheid binaries. Low mass companions are strongly preferred, especially when corrections for incompleteness are included.

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Mazeh, Tsevi, Dorit Goldberg, and David W. Latham. "The Mass Distribution of Extrasolar Planet Candidates and Spectroscopic Binary Low-Mass Companions." Astrophysical Journal 501, no. 2 (July 10, 1998): L199—L203. http://dx.doi.org/10.1086/311464.

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35

Athanasiadis, Tilemachos M., Marina Berezina, John Antoniadis, David J. Champion, Marilyn Cruces, Laura Spitler, and Michael Kramer. "A search for pulsar companions around low-mass white dwarfs." Monthly Notices of the Royal Astronomical Society 505, no. 4 (May 31, 2021): 4981–88. http://dx.doi.org/10.1093/mnras/stab1580.

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ABSTRACT We report on a search for pulsars at the positions of eight low-mass white dwarfs and one higher mass white dwarf with the 100-m Effelsberg Radio Telescope. These systems have orbital parameters suggesting that their unseen companions are either massive white dwarfs or neutron stars (NSs). Our observations were performed at 1.36 GHz, reaching sensitivities of 0.1–0.2 mJy. We searched our data accounting for the possible acceleration and jerk of the pulsar signals due to orbital motion, but found no significant pulsar signals. Considering our result jointly with 20 non-detections of similar systems with the Greenbank Radio Telescope, we infer fNS ≤ 0.10, for the fraction of NSs orbiting these white dwarfs. We discuss the sensitivity of this result to the underlying assumptions and conclude with a brief discussion on the prospects of targeted surveys for discovering millisecond pulsars.

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Ivanova, N. "Low-Mass X-Ray Binaries with Pre-Main-Sequence Companions." Astrophysical Journal 653, no. 2 (December 1, 2006): L137—L140. http://dx.doi.org/10.1086/510672.

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Soker, Noam, and Amos Harpaz. "Overluminous Blue Horizontal‐Branch Stars Formed by Low‐Mass Companions." Astrophysical Journal 660, no. 1 (May 2007): 699–703. http://dx.doi.org/10.1086/513268.

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38

Comerón, F. "Discarded candidate companions to low-mass members of Chamaeleon I." Astronomy & Astrophysics 537 (January 2012): A97. http://dx.doi.org/10.1051/0004-6361/201117590.

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39

Mazeh, T., D. W. Latham, and P. Stefanik. "Radial velocity search for low mass companions of nearby stars." Acta Astronautica 42, no. 10-12 (May 1998): 593–98. http://dx.doi.org/10.1016/s0094-5765(98)00013-7.

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40

Vogt, Steven S., R. Paul Butler, Geoffrey W. Marcy, Debra A. Fischer, Dimitri Pourbaix, Kevin Apps, and Gregory Laughlin. "Ten Low‐Mass Companions from the Keck Precision Velocity Survey." Astrophysical Journal 568, no. 1 (March 20, 2002): 352–62. http://dx.doi.org/10.1086/338768.

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Wolk, Scott J., and S. C. Beck. "On the possibility of outflows from very low-mass companions." Publications of the Astronomical Society of the Pacific 102 (July 1990): 745. http://dx.doi.org/10.1086/132697.

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42

Guenther, E. W., and G. Wuchterl. "Companions of old brown dwarfs, and very low mass stars." Astronomy & Astrophysics 401, no. 2 (March 21, 2003): 677–83. http://dx.doi.org/10.1051/0004-6361:20030149.

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Campbell, Bruce. "A Search for Planetary-Mass Companions to Nearby Stars." Highlights of Astronomy 8 (1989): 109–10. http://dx.doi.org/10.1017/s1539299600007541.

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AbstractNine of 18 stars observed with a high precision radial velocity technique show long term, low level variations which imply the presence of companions in the range of 1 to 10 Jupiter masses. These companions could represent the tip of the planetary-mass spectrum.

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Schaffenroth, V., B. N. Barlow, S. Geier, M. Vučković, D. Kilkenny, M. Wolz, T. Kupfer, et al. "The EREBOS project: Investigating the effect of substellar and low-mass stellar companions on late stellar evolution." Astronomy & Astrophysics 630 (September 24, 2019): A80. http://dx.doi.org/10.1051/0004-6361/201936019.

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Eclipsing post-common-envelope binaries are highly important for resolving the poorly understood, very short-lived common-envelope phase of stellar evolution. Most hot subdwarfs (sdO/Bs) are the bare helium-burning cores of red giants that have lost almost all of their hydrogen envelope. This mass loss is often triggered by common-envelope interactions with close stellar or even substellar companions. Cool companions to hot subdwarf stars such as late-type stars and brown dwarfs are detectable from characteristic light-curve variations – reflection effects and often eclipses. In the recently published catalog of eclipsing binaries in the Galactic Bulge and in the Asteroid Terrestrial-impact Last Alert System (ATLAS) survey, we discovered 125 new eclipsing systems showing a reflection effect seen by visual inspection of the light curves and using a machine-learning algorithm, in addition to the 36 systems previously discovered by the Optical Gravitational Lesing Experiment (OGLE) team. The Eclipsing Reflection Effect Binaries from Optical Surveys (EREBOS) project aims at analyzing all newly discovered eclipsing binaries of the HW Vir type (hot subdwarf + close, cool companion) based on a spectroscopic and photometric follow up to derive the mass distribution of the companions, constrain the fraction of substellar companions, and determine the minimum mass needed to strip off the red-giant envelope. To constrain the nature of the primary we derived the absolute magnitude and the reduced proper motion of all our targets with the help of the parallaxes and proper motions measured by the Gaia mission and compared those to the Gaia white-dwarf candidate catalog. It was possible to derive the nature of a subset of our targets, for which observed spectra are available, by measuring the atmospheric parameter of the primary, confirming that less than 10% of our systems are not sdO/Bs with cool companions but are white dwarfs or central stars of planetary nebula. This large sample of eclipsing hot subdwarfs with cool companions allowed us to derive a significant period distribution for hot subdwarfs with cool companions for the first time showing that the period distribution is much broader than previously thought and is ideally suited to finding the lowest-mass companions to hot subdwarf stars. The comparison with related binary populations shows that the period distribution of HW Vir systems is very similar to WD+dM systems and central stars of planetary nebula with cool companions. In the future, several new photometric surveys will be carried out, which will further increase the sample of this project, providing the potential to test many aspects of common-envelope theory and binary evolution.

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Grieves, Nolan, François Bouchy, Monika Lendl, Theron Carmichael, Ismael Mireles, Avi Shporer, Kim K. McLeod, et al. "Populating the brown dwarf and stellar boundary: Five stars with transiting companions near the hydrogen-burning mass limit." Astronomy & Astrophysics 652 (August 2021): A127. http://dx.doi.org/10.1051/0004-6361/202141145.

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We report the discovery of five transiting companions near the hydrogen-burning mass limit in close orbits around main sequence stars originally identified by the Transiting Exoplanet Survey Satellite (TESS) as TESS objects of interest (TOIs): TOI-148, TOI-587, TOI-681, TOI-746, and TOI-1213. Using TESS and ground-based photometry as well as radial velocities from the CORALIE, CHIRON, TRES, and FEROS spectrographs, we found the companions have orbital periods between 4.8 and 27.2 days, masses between 77 and 98 MJup , and radii between 0.81 and 1.66 RJup . These targets have masses near the uncertain lower limit of hydrogen core fusion (~73-96 MJup ), which separates brown dwarfs and low-mass stars. We constrained young ages for TOI-587 (0.2 ± 0.1 Gyr) and TOI-681 (0.17 ± 0.03 Gyr) and found them to have relatively larger radii compared to other transiting companions of a similar mass. Conversely we estimated older ages for TOI-148 and TOI-746 and found them to have relatively smaller companion radii. With an effective temperature of 9800 ± 200 K, TOI-587 is the hottest known main-sequence star to host a transiting brown dwarf or very low-mass star. We found evidence of spin-orbit synchronization for TOI-148 and TOI-746 as well as tidal circularization for TOI-148. These companions add to the population of brown dwarfs and very low-mass stars with well measured parameters ideal to test formation models of these rare objects, the origin of the brown dwarf desert, and the distinction between brown dwarfs and hydrogen-burning main sequence stars.

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Struck-Marcell, Curtis. "Caustic Waves in Galaxy Disks Produced in Collisions with Low Mass Companions." International Astronomical Union Colloquium 124 (1990): 743–47. http://dx.doi.org/10.1017/s0252921100005911.

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At this meeting much attention has been focussed on interactions and mergers between roughly equal mass galaxies. On the contrary, I will begin by mentioning a few justifications for studying collisions with relatively low mass companions, specifically, less than about one third of the mass of the target galaxy. The first is simply that such collisions are likely to be common, given that the galaxy luminosity function is broad. The second reason is that such collisions have evidently been less well studied than collisions between nearly equal partners. However, there are a few important exceptions to this generalization, including the sinking satellite problem (e.g. Quinn and Goodman 1986), and the collisional model for the formation of shell galaxies in which a companion of negligible mass is completely disrupted(e.g. Dupraz and Combes 1986, Hernquist and Quinn 1988). The third, and potentially most important reason, is that the effects of a collision with a low-mass companion are less extreme (at least from the big galaxy’s point of view!). Thus, these effects are closer to the theorist’s ideal of a “small perturbation”. This is important for both conceptually understanding the effects of the collision, and for justifying the use of approximate numerical techniques (e.g. restricted three-body) to study them.

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47

LEE, CHANG-HWAN, and GERALD E. BROWN. "ON THE THEORY OF GAMMA RAY BURSTS AND HYPERNOVAE: THE BLACK HOLE SOFT X-RAY TRANSIENT SOURCES." International Journal of Modern Physics A 18, no. 04 (February 10, 2003): 527–76. http://dx.doi.org/10.1142/s0217751x03012266.

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We show that a common evolutionary history can produce the black hole binaries in the Galaxy in which the black holes have masses of ~ 5 - 10M⊙. In the black hole binaries with low-mass, ≲ 2.5M⊙ ZAMS (zero age main sequence) companions, the latter remain in main sequence during the active stage of soft X-ray transients (SXT's), most of them being of K or M classification. In two intermediate cases, IL Lupi and Nova Scorpii with ZAMS ~ 2.5M⊙ companions the orbits are greatly widened because of large mass loss in the explosion forming the black hole, and whereas these companions are in late main sequence evolution, they are close to evolving. Binaries with companion ZAMS masses ≳ 3M⊙ are initially "silent" until the companion begins evolving across the Herzsprung gap. We provide evidence that the narrower, shorter period binaries, with companions now in main sequence, are fossil remnants of gamma ray bursters (GRB's). We also show that the GRB is generally accompanied by a hypernova explosion (a very energetic supernova explosion). We further show that the binaries with evolved companions are good models for some of the ultraluminous X-ray sources (ULX's) recently seen by Chandra in other galaxies. The great regularity in our evolutionary history, especially the fact that most of the companions of ZAMS mass ≲ 2.5M⊙ remain in main sequences as K or M stars can be explained by the mass loss in common envelope evolution to be Case C; i.e. to occur only after core He burning has finished. Since our argument for Case C mass transfer is not generally understood in the community, we add an appendix, showing that with certain assumptions which we outline we can reproduce the regularities in the evolution of black hole binaries by Case C mass transfer.

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Absil, O., J. B. Le Bouquin, J. Lebreton, J. C. Augereau, M. Benisty, G. Chauvin, C. Hanot, A. Mérand, and G. Montagnier. "Deep near-infrared interferometric search for low-mass companions aroundβ Pictoris." Astronomy and Astrophysics 520 (September 2010): L2. http://dx.doi.org/10.1051/0004-6361/201015156.

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Oetiker, Brian, Nebojsa Duric, John T. McGraw, and Melissa A. McGrath. "A Spectrophotometric Technique for Detecting Companions of Low‐Mass M Dwarfs." Publications of the Astronomical Society of the Pacific 113, no. 784 (June 2001): 703–14. http://dx.doi.org/10.1086/320804.

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Heacox, William D. "On the Nature of Low‐Mass Companions to Solar‐like Stars." Astrophysical Journal 526, no. 2 (December 1999): 928–36. http://dx.doi.org/10.1086/308033.

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