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Testing the Interaction Between a Substellar Companion and a Debris Disk in the Hr 2562 System
Get PDFThe HR 2562 system is a rare case where a brown dwarf companion resides in a cleared inner hole of a debris disk, offering invaluable opportunities to study the dynamical interaction between a substellar companion and a dusty disk. We present the first ALMA observation of the system as well as the continued Gemini Planet Imager monitoring of the companion\u27s orbit with six new epochs from 2016 to 2018. We update the orbital fit, and in combination with absolute astrometry from GAIA, place a 3σ upper limit of 18.5 M J on the companion\u27s mass. To interpret the ALMA observations, we used radiative transfer modeling to determine the disk properties. We find that the disk is well resolved and nearly edge-on. While the misalignment angle between the disk and the orbit is weakly constrained, due to the short orbital arc available, the data strongly support a (near) coplanar geometry for the system. Furthermore, we find that the models that describe the ALMA data best have inner radii that are close to the companion\u27s semimajor axis. Including a posteriori knowledge of the system\u27s SED further narrows the constraints on the disk\u27s inner radius and places it at a location that is in reasonable agreement with (possibly interior to) predictions from existing dynamical models of disk truncation by an interior substellar companion. HR 2562 has the potential over the next few years to become a new test bed for dynamical interaction between a debris disk and a substellar companion
Direct Discovery of the Inner Exoplanet in the Hd 206893 System: Evidence for Deuterium Burning in a Planetary-Mass Companion
Get PDFAims. HD 206893 is a nearby debris disk star that hosts a previously identified brown dwarf companion with an orbital separation of ~ 10 au. Long-Term precise radial velocity (RV) monitoring, as well as anomalies in the system proper motion, has suggested the presence of an additional, inner companion in the system. Methods. Using information from ongoing precision RV measurements with the HARPS spectrograph, as well as Gaia host star astrometry, we have undertaken a multi-epoch search for the purported additional planet using the VLTI/GRAVITY instrument. Results. We report a high-significance detection over three epochs of the companion HD 206893c, which shows clear evidence for Keplerian orbital motion. Our astrometry with ~ 50-100 µarcsec precision afforded by GRAVITY allows us to derive a dynamical mass of 12.7MJup and an orbital separation of 3.53 au for HD 206893c. Our fits to the orbits of both companions in the system use both Gaia astrometry and RVs to also provide a precise dynamical estimate of the previously uncertain mass of the B component, and therefore allow us to derive an age of 155 ± 15 Myr for the system. We find that theoretical atmospheric and evolutionary models that incorporate deuterium burning for HD 206893c, parameterized by cloudy atmosphere models as well as a hybrid sequence (encompassing a transition from cloudy to cloud-free), provide a good simultaneous fit to the luminosity of both HD 206893B and c. Thus, accounting for both deuterium burning and clouds is crucial to understanding the luminosity evolution of HD 206893c. Conclusions. In addition to using long-Term RV information, this effort is an early example of a direct imaging discovery of a bona fide exoplanet that was guided in part by Gaia astrometry. Utilizing Gaia astrometry is expected to be one of the primary techniques going forward for identifying and characterizing additional directly imaged planets. In addition, HD 206893c is an example of an object narrowly straddling the deuterium-burning limit but unambiguously undergoing deuterium burning. Additional discoveries like this may therefore help clarify the discrimination between a brown dwarf and an extrasolar planet. Lastly, this discovery is another example of the power of optical interferometry to directly detect and characterize extrasolar planets where they form, at ice-line orbital separations of 2-4 au
Episode 11: Susannah Howe, DC Director
Get PDFThis episode features an interview with Susannah Howe, the Design Clinic Director at Smith College. The interviewers are recent graduates Harriet Wright and Sophie Yates from the Zipline-DC2122 team
Annulled: Marriage, Sex, and Violence in the Archives of the Ottoman East
Get PDFOn October 2, 1878, Narduhi Magarian and Sahag Ağa Tevrizian were wed in the Ottoman border town of Erzurum. Soon afterwards, both of them sought freedom from this union, one foisted upon them by Narduhi’s wealthy, violent, and alcohol-addled father, Garabed Efendi Magarian. The toxic fallout of this failed marriage prompted the Armenian Patriarchate of Constantinople to order an investigation. The resulting witness testimonies, held in a fragment of the Patriarchate’s records in Paris, describe the beginnings of this coerced marriage, the domestic violence it involved, and the anxieties about sex and potency that it stoked. These letters also have much to say about national and gendered silences imposed by the indefinite inaccessibility of the Armenian Patriarchate’s archive in Istanbul. This marriage highlights an aftereffect of national violence: how the apprehensions swirling around it serve to stifle history-writing about gendered violence. Through a single episode in the life of an Armenian woman, it also offers a view onto domestic abuse, marriage, and sex in a crisis-ridden Ottoman borderland. Although there may be an urge to recover Narduhi’s voice, avoiding that temptation shows how her story is important less for what it recovers than for two historical narratives that it disrupts: one that circumscribes women’s history with ideals of self-sacrifice and moral rectitude and another that attempts to construct a singular national past in the wake of catastrophe
Will Artificial Superintelligence Kill Us?
No full textThrough advancements in machine learning, we are progressing towards the development of artificial superintelligence (ASI). As machine learning often yields opaque results, our predictions about ASI behavior in novel situations are uncertain. Alarmingly, some theories suggest that ASI might eliminate humans to secure resources for its own use.
Even if ASI doesn\u27t intentionally harm us, our existence could be endangered if our fundamental necessities, like clean air, water, and a stable climate, interfere with the ASI\u27s optimal functioning. Additionally, intense conflicts among ASIs could render the Earth uninhabitable for humans.
Market forces drive companies to chase ASI development, even if they believe that ASI could cause human extinction. This mainly occurs as every company understands that halting ASI research could give their competitors an edge. Stopping the global pursuit of ever more powerful AI seems unlikely, given the growing financial and military advantages attached to it. In addition, older political leaders, who might benefit from the potential life-extending effects of ASI, could push for rapid ASI development, despite the substantial risk of human extinction.
I believe our best chance at survival depends on the possibility that even unaligned ASIs might see a practical benefit of preserving humanity and sharing a small part of the universe\u27s resources with us. Predicting our survival chances is challenging, but I cautiously estimate them to be between ten and forty percent.
This paper explores the important issues related to ASI risk, evaluates potential differences in expert opinions on each subject, and points out areas for future research to improve our comprehension of this complicated scenario
Beyond Myopia in Communications and the Sociology of Media
No full textThis special issue of Information, Communication, and Society (ICS) is edited by the Communication, Information Technologies, and Media Sociology (CITAMS) section of the American Sociological Association and includes papers that were first presented at either the 2021 or 2022 ASA meetings or Media Sociology Symposia. For this special issue, an innovative editorial approach was taken that brought the editing process into a graduate classroom. That process is described below along with a brief introduction to themes of the selected articles. Key themes for this special issue include content analysis, ethics, privacy, new economy, and digital inequality
Reduced Growth Mindset as a Mechanism Linking Childhood Trauma with Academic Performance and Internalizing Psychopathology
Get PDFBackground
Despite the high prevalence of childhood adversity and well-documented associations with poor academic achievement and psychopathology, effective, scalable interventions remain largely unavailable. Existing interventions targeting growth mindset—the belief that personal characteristics are malleable—have been shown to improve academic achievement and symptoms of psychopathology in youth.
Objective
The present study examines growth mindset as a potential modifiable mechanism underlying the associations of two dimensions of childhood adversity—threat and deprivation—with academic achievement and internalizing psychopathology. Participants and setting Participants were 408 youth aged 10–18 years drawn from one timepoint of two longitudinal studies of community-based samples recruited to have diverse experiences of childhood adversity.
Method
Experiences of threat and deprivation were assessed using a multi-informant, multi-method approach. Youth reported on growth mindset of intelligence and symptoms of anxiety and depression. Parents provided information about youths\u27 academic performance.
Results
Both threat and deprivation were independently associated with lower growth mindset, but when accounting for co-occurring adversities, only the association between threat and lower growth mindset remained significant. Lower growth mindset was associated with worse academic performance and greater symptoms of both anxiety and depression. Finally, there was a significant indirect effect of experiences of threat on both lower academic performance and greater symptoms of anxiety through lower growth mindset.
Conclusions
Findings suggest that growth mindset could be a promising target for efforts aimed at mitigating the impact of childhood adversity on academic achievement and psychopathology given the efficacy of existing brief, scalable growth mindset interventions
Narratives Reflecting Theory of Mind among Bilingual Lyuli Children of Uzbekistan
Get PDFThis is the first known study of the socio-cognitive development of Lyuli children, a Roma-type group living in Bukhara in Uzbekistan. The research was conducted in schools in Bukhara serving both Lyuli children and Uzbek children, both of whom are multi-lingual but whose sociolinguistic circumstances are somewhat different. There has been less cross-cultural work on later stages of Theory of Mind development, in which children have to make inferences about the mental states of characters in a complex narrative. The research here shows that the children from both groups do remarkably well on these tasks, and their multilingualism is hypothesized to be the source of their success relative to other children studied with similar narratives
