List of Abstracts

 

 

 

 

 

Iranian National Observatory; past, present and vision

 

Habib Khosroshahi

 

The INO project is now approaching the final stage of its development, passing major milestones including the completion of the civil construction, installation of the dome structure, and the 3.4m optical telescope. The telescope has been installed on Mt Gargash, 3600m, and is going through various tests which will be followed by full integration of all subsystems in 2022 and the first light before the scientific commissioning begins. I will review the past, describe the current status, elaborate on the future steps.


INO340 Instrumentation plan and instrument adapter

 

Habib Khosroshahi

 

To take advantage of the unique location of the INO amongst northern hemisphere modern mid-size telescope, the INO340 instrument adapter has been designed and developed in a fashion that reduces instrument change overhead and offers a platform for the development and commissioning of new instruments. As such the adapter can hold 2 or 3 lightweight instruments and 1 large and heavy instrument on the main Cassegrain focus. The instrument switch time is less than 1 minute which makes it suitable to respond to transients. The adapter also hosts common services, such as the auto-guiding subsystem as well as the wavefront sensing unit to control the mirrors.


Galaxy groups and clusters

 

Habib Khosroshahi

 

Galaxy clusters are the largest gravitationally bound systems in the universe. Their masses range from 10^14‐10^15 solar masses. Galaxy groups have a smaller mass around 10^12‐10^14. There is, however, no clear boundary between galaxy groups and clusters. The real difference is in the physical mechanisms that are taking place in each of these systems driven by galaxy velocity, IGM properties, and AGN activities. Galaxy groups are complex and rapidly evolving systems. In the most popular structure formation model they stand between the most massive gravitationally bound systems and galaxies, the building block of the Universe. Thus, they are host to physical mechanisms which are not efficient in galaxy clusters or in the field. Mid-size telescopes have contributed to the largest development in our understanding of galaxy systems. IPM School of astronomy has contributed significantly to the development of science in this subject. I will review how INO340 can help further achieve science goals.


مکان یابی رصد خانه ملی ایران

Sadollah Nasiri

 

 

 

 

 

 

 


مکانیک تلسکوپ ۳٫۴ متری (سازه، سامانه حرکتی و یاتاقانها)

 

Masoud Bidar

 

تلسکوپ ملی ایران با آرایش سمتی-ارتفاعی، دارای سازه 90 تنی به ابعاد تقریبی قطر 7.5 متر و ارتفاع 11 متر است که بر بالای ستون بتونی به ارتفاع 7 متر از سطح زمین نصب شده است.  تلسکوپ شامل حدود 8150 قطعه است که توسط جوش و دهها هزار پیچ و مهره سازه به هم متصل شده اند. سامانه حرکتی تلسکوپ در هر یک از سه محور اصلی از دو الکترو سروو موتور بعلاوه یک چرخدنده است که با به صفر رساندن لقی و به کمک انکودر بسیار دقیق در هر محور منجر به حرکت بسیار دقیق (با دقت حدود 0.2 ثانیه قوسی) در حرکت تلسکوپ می گردد.  وزن قسمت متحرک تلسکوپ (73 تن) نوسط چهار عدد یاتاقان هیدرواستاتیکی به صورت شناور در می آید. سایر محور ها توسط یاتاقاتهای ساچمه ای مهار می شوند. در بهینه سازی طراحی سازه تلسکوپ از آنالیزهای اجزاء محدود ایستا، ارتعاشی، زلزله و باد استفاده شده است. طراحی سازه تلسکوپ حدود 70000 نفرساعت نیروی مهندسی بکارگرفته شده است.


INO340 meter Telescope Control System: Philosophy, Architecture, Design and Development

 

Reza Ravanmehr

 

تلسکوپ INO340 یک مجموعه بسیار پیچیده از سیستم‌های مختلف است که شامل تعداد زیادی قطعات اپتیکی ومکانیکی، مکانیزم های الکترومکانیکی و یک سامانه کنترلی (INOCS1) منحصر بفرد می باشد. تلسکوپ با بخش های مختلفی از رصدخانه مثل محفظه یا ابزارگان در ارتباط مستقیم است. از این رو لازم است که سامانه کنترلی تلسکوپ برای مدیریت مناسب فعالیت‌های مورد نیاز به سامانه های کوچکتری تقسیم شود. از جمله آن ها می توان به سامانه کنترلی سطح بالا، سامانه کنترل تلسکوپ، سامانه اپتیک فعال، سامانه کنترل محفظه، سامانه مانیتورینگ عوامل محیطی و غیره اشاره کرد. سامانه کنترل تلسکوپ اصلی رصدخانه ملی مسئول رساندن نور از شیئ سماوی به ابزار علمی نصب شده بر روی تلسکوپ است. این کار با کنترل تمام مکانیزم های موجود و المانهای نوری و مطابق با الزامات مشخص شده در حضور اختلالات معین انجام خواهد شد. فلسفه INOCS به‌گونه ای تدوین شده است که کلیه سامانه های کنترلی ، سامانه ایمنی، سامانه های رصدی و کاربری و سامانه های ابزار دقیق را شامل شده و مشخصات مورد نیاز و ارتباطات بین آنها را تعریف نماید. این فلسفه دربردارنده زوایا و ابعاد مختلفی در راستای هر چه کاراتر شدن طراحی و توسعه سامانه کنترل نظیر فرآیند تدریجی توسعه و تجمیع، استراتژیهای مناسب سامانه های کنترلی توزیعی بی درنگ، بررسی و تحلیل الزامات برای شناسایی صحیح و به موقع پارامترهای مختلف سیستم و …میباشد. پایبندی به این فلسفه تضمین کننده یکپارچگی و همنوایی سامانه های مختلف INOCS در بستر سالهای متمادی طراحی و توسعه این سیستم توسط مهندسین مختلف بوده است. مطالعات انجام شده در فلسفه موجود در INOCS به عنوان پیش زمینه دانش به تیم مهندسی  کنترل رصدخانه  کمک می کند تا هرچه بیشتر بتوانند فرایند های تدوین شده را پیگیری کرده، مشخصات و نیازمندیهای هر زیرسامانه را به درستی شناسایی نموده و از آنها در طراحی و پیاده سازی موثر آن ها استفاده کنند. برای طراحی و توسعه سامانه کنترل تلسکوپ رصدخانه ملی ایران اولین گام ارائه یک معماری متناسب با نیازمندیهای عملکردی و غیر عملکردی تلسکوپ است. در این راستا معماری این سامانه با توجه به مفاهیم و استراتژیهای سیستمهای توزیع شده بی درنگ طراحی شده است به گونه ای که بتواند بهترین عملکرد با بالاترین سطح قابلیت اطمینان را ارائه کند. INOCS باید بتواند مسائلی نظیر طراحی ماجولار، استفاده از اینترفیس های مناسب، تفکیک وظایف و نگرانیها، مقیاس‌پذیری، کنترل ترافیک و ازدحام و …را در اختیار بگذارد.

 


INO340 meter Enclosure Building and Rotating Dome

 

Seyed Mohamad Mohajer

 

To take advantage of the unique location of the INO amongst northern hemisphere modern mid-size telescope, the INO340 instrument adapter has been designed and developed in a fashion that reduces instrument change overhead and offers a platform for the development and commissioning of new instruments. As such the adapter can hold 2 or 3 lightweight instruments and 1 large and heavy instrument on the main Cassegrain focus. The instrument switch time is less than 1 minute which makes it suitable to respond to transients. The adapter also hosts common services, such as the auto-guiding subsystem as well as the wavefront sensing unit to control the mirrors.

 

 


 

Description of the INO340 Coating Plant

 

Hooshdad Jenab

 

این سامانه بزرگترین سامانه لایه نشانی با روش کندو پاش  (Sputtering) در کشور است. این سامانه شامل ۳ نوع پمپ خلا و یک مخزن خلا به قطر 4 متر و طول 2.7 متر است. دقت لایه نشانی این مجموعه 5 درصد تغییرات ضخامت در کل سطح (سطح آینه به قطر 3.4 متر) می‌باشد تا بتواند آینه را با ضخامت 100 نانومتر لایه‌نشانی کند. در این سامانه خلاء حدود 5e-7  میلی بار ایجاد می شود. برای لایه نشانی از آلومینیوم با درصد خلوص 99.999  (5N) استفاده می شود. این سامانه که برای اولین بار در ایران با این ابعاد ساخته می‌شود، با در نظر گرفتن سیستم‌های حرکتی و فیکسچرهای آینه  در حدود 19 تن وزن دارد. کل حجم داخلی این محفظه حدود 28 متر مکعب است. همچنین کل مساحت داخلی این محفظه (شامل بستر آینه ، غرفه ها و درخت سوت زدن ، دستگاه پاشش ، ماسک ، الکترودهای تخلیه درخشش ، فلنج های مختلف و لوله های متصل به محفظه اصلی) حدود 90 متر مربع تخمین زده می شود.  محفظه از جنس استنلس استیل درجه 304 ساخته شده که با فرآیند جوشکاری TIG ساخته شده است. فلنج های مختلف همه مطابق با استانداردهای بین المللی ساخته شده و پس از طی مراحل ساخت و پولیش سطوح داخلی، کل محفظه با استفاده از ردیاب نشت هلیوم با حساسیت بالا نشتیابی شده است.

این سیستم شامل سیستم پمپاژ، دستگاه‌های اندازه‌گیری فشار، شیرهای خلاء و سایر مکانیسم‌های نصب شده است. برای رسیدن به فشار در محدوده 10-7 ميلی بار، سیستم پمپاژ پیشنهادی شامل پمپ های زیر است: پمپ اسکرو با سرعت پمپاژ  m3 / h600، پمپ روتز با سرعت پمپاژ m3 / h 2000 ، پمپ توربومولکولار با سرعت کامل پمپ 6400 لیتر در ثانیه.

روند خلاء با تخلیه محفظه با استفاده از پمپ اسکرو شروع می شود. تخلیه محفظه با فشار 10 mbar برای شروع پمپ روتز انجام می شود. بعد از این مدت، پمپ روتز در چند دقیقه محفظه را تا 0.1 mbar تخلیه می‌نماید. در این مرحله پمپ های توربو آماده شروع هستند، آنها محفظه را به طور عمده در رژیم جریان مولکولی تخلیه می‌کنند، که در آن حجم داخلی اهمیتی ندارد و مساحت کل داخلی تعیین کننده است. فشار مخزن به محدوده  3×10-6  می‌رسد. این دامنه فشار برای شروع فرآیند Glow Discharge با تزریق گازهای فرآیندی (اکسیژن و آرگون) در داخل محفظه مناسب است. پس از حدود 30-45 دقیقه فرآیند Glow Discharge خاتمه می یابد. سپس با تزریق گاز فرآیند (Ar) ، لايه‌نشانی آغاز شود.

روش کندوپاش نیز شامل سه مرحله تبخیر ماده منبع، انتقال بخار از منبع به جسم و تشکیل لایه نازک روی جسم با انباشت بخار منبع مورد نظر است. در روش کندوپاش، برای این‌که ماده منبع به فاز بخار درآید، از بر هم کنش فیزیکی ذره‌هایی که به ماده منبع برخورد می‌کنند، استفاده می‌شود. ماده منبع که به ولتاژ منفی متصل است، نقش کاتد را دارد. با بمباران و برخورد ذرات پر انرژی به سطح منبع، اتم‌ها یا مولکول‌های آن از سطح جدا شده و به بیرون پرتاب می‌شوند و درمیدان ایجادکننده پلاسما شتاب می‌گیرند. جسم مورد نظر به ولتاژ مثبت متصل است و در واقع نقش آند را دارد، بنابراین لایه‌ای از جنس منبع روی آن انباشته می‌شود. این روش برای ایجاد پوشش و ساخت لایه‌ نازک آلومینیم بر روی آینه استفاده می‌شود.


INO 3.4 meter telescope: Active Optics System and Algorithm

 

Mehdi Saeidifar

 

An active optics algorithm and the system are being developed for the Iranian National Observatory 3.4 m telescope (INO340). The telescope primary mirror (M1) is flexible and the secondary mirror (M2) is rigid. M1 support consists of 60 active axial actuators (AAC), 32 passive lateral actuators (LAC), 3 axial fixed-points, and 3 lateral fixed-points; and M2 is supported by an accurate hexapod. M1 surface shape and M2 positions will be actively controlled using an active optics system, to reach the best image quality. Correction can be done using either a look-up table in open-loop control or the wavefront error in closed-loop control. There are three levels of the control loop in AOS: 1- A proportional controller using two input/output valves to regulate every single actuator, 2- Inner-loop using the feedback of the axial fixed-points’ load cell and the axial actuators to equilibrate M1 within the bandwidth of 1 [Hz], 3- Outer-loop using a Shack-Hartman wavefront sensor (SHWFS) and the axial actuators to remove optical aberrations within the bandwidth of 0.01 [Hz]. A test setup for the axial actuator is provided to design and optimize proportional controller hardware and software. The axial pneumatic actuators deliver a compressive force with an amplitude between 150 and 900 [N]. The actuators’ accuracy is 0.2 [N] within the stroke of ±10 [N] which is achievable in 0.8 [s].

 

 


طراحی و ساخت حسگر جبهه موج تلسکوپ ۳٫۴ متری

 

Ramin Shomali

 

In this talk, the INO’s Shack- Hartmann wavefront sensor (SHWFS) will be described. The INO’s Shack-Hartmann Wavefront Sensor is installed in the probe system.  It receives the light from the same star used for the autoguiding system. A pickup mirror scans the technical field radially and tangentially guides the light to a beam splitter. The wavefront sensor optics consist of a 46.7 mm focal length 7×7 square geometry lenslet array, each lenslet has a 500-micrometer pitch with a spherical lens profile, and a 40 mm focal length collimator lens as well as a CCD with  0.06 arcsec pixel scale. Each lenslet has a size of 48.5 cm x 48.5 cm referred to as the telescope entrance pupil. Software for SHWFS measures the slopes of the wavefront at 36 positions and using the slopes calculates the annular Zernike modes of the wavefront. Also, the performance of the wavefront sensor in terms of the altitude angle of the mirror, the magnitude of the guide star, and the Fried parameters will be discussed.


Formation and Evolution of Nearby Galaxies

 

Atefeh Javadi

 

The evolution of galaxies is driven by the birth and death of stars.  The evolved stars are excellent tracers, not just of the feedback processes, but also of the underlying populations that were formed from millions to billions of years prior to their appearance.  These stars can be resolved in all of the nearby galaxies. Therefore, the Local Group of galaxies offers us a superb near-field cosmology site. Here we can reconstruct the formation histories, and probe the structure and dynamics, of spiral galaxies, of the many dwarf satellite galaxies surrounding the Milky Way and Andromeda, and of isolated dwarf galaxies. It also offers a variety of environments in which to study the detailed processes of galaxy evolution through studying the mass-loss mechanism and dust production by cool evolved stars. I have recently pioneered the monitoring observation of the majority of dwarf galaxies in the Local Group. This research will gather independent diagnostics of the star formation histories of different types of dwarf galaxies found in different environments, which help build a comprehensive picture of galaxy formation and evolution in the nearby galaxies. In this talk, I will first review our recent efforts to identify mass-losing Asymptotic Giant Branch (AGB) stars and red supergiants (RSGs) in Local Group galaxies and to correlate spatial distributions of the AGB stars of different mass with galactic structures. Then, I will outline our methodology to reconstruct the star formation histories using variable pulsating AGB stars and RSGs and present the results for rates of mass–loss and dust production by pulsating AGB stars and their analysis in terms of stellar evolution and galaxy evolution. I will also review INO’s capabilities in achieving science goals regarding the formation and evolution of nearby galaxies. In the end, I will talk about our future observations with the James Webb Space Telescope in order to characterize dust formation in a primitive environment.

 


Iranian National Observatory Science Cases

Atefeh Javadi

 

 

 

 


طیف سنج نسل اول تلسکوپ ۳٫۴ متری

 

Ayatollah Karimzadeh

 

Many astronomy studies are based on spectral measurements of the stars and heavenly bodies. In this paper, the design of medium-resolution for an astronomical 3.4 m telescope is reported. By adding this system, the best use of a 3.4 m telescope can be done. A spectrograph slit can be placed in the focal plane of the telescope.

Keywords: Spectrograph; Telescope; grating; resolution power


An Introduction to Iranian National Observatory’s Lens Array Observing Facility

 

Hamed Altafi

 

«سامانه رصدی آرایه لنز یکی از تلسکوپ های برنامه ریزی شده رصدخانه ملی ایران است که به منظور رصد اجرامی با درخشندگی سطحی بسیار پایین در نور مرئی طراحی و ساخته شده است. این سامانه از سه لنز 400 میلیمتر با ویژگی های اپتیکی خاص تشکیل شده هست و هر لنز به یک سی.سی.دی جداگانه متصل است. به این ترتیب امکان رصد همزمان در سه فیلتر مختلف وجود دارد. ویژگی اصلی این سامانه، رصد بلند مدت با میدان دید باز است تا امکان دریافت تصاویری عمیق از اجرام کم نور و گسترده فراهم شود. علاوه بر این امکان رصد ستاره های متغیر و پدیده های گذرا نیز فراهم است. سامانه آرایه لنز در سال 1398 در محل پایشگاه رصدخانه ملی ایران نصب شده و هم اکنون در حال بهره برداری است.

در این سخنرانی به معرفی فنی و جنبه های رصدی سامانه آرایه لنز می پردازیم»

 

 


The first generation cryostat at INO

 

Reza Rezaei

 

Using a cryostat decreases the dark current by several orders of magnitude, so it is widely used in astrophysics as well as other disciplines of physics. I present the design concept and structure of the first generation cryostat at INO. Cryostats are vacuum flasks containing cryogen-like liquid nitrogen to provide a cold link to the target (here the detector). The first generation INO cryostat is a liquid nitrogen (LN2) cryostat with a single vacuum flask, radiation shield, and thermodynamic accessories. The cryostat hosts the imaging or the spectrograph detectors. The existing gates at the INO adapter as well as the heat load will determine the duty cycle.

 


A visionary national solar telescope

 

Reza Rezaei

 

What kind of solar telescope is appropriate for Iran? After a brief review of modern solar telescopes, I present a few solar telescopes which can be realized as the national solar telescopes of Iran. Modern solar telescopes have either a compact structure and a hot focus or a large structure with a cold focus. All current operating solar telescopes fall in these two categories and each one has its own positive and negative issues. I would argue that for Iran in the new century, the best option would be to have a moderate size ground facility as well as a small orbital telescope. While the former is a semi-automatic instrument and delivers high-spatial resolution observations, the latter performs solar observations at diverse wavelengths which are not accessible on the ground.

 

 


Prospect of spectroscopic facilities for mid-size (2-4m) telescopes

 

Alireza Molaeinejad

 

The mid-size class telescopes (2-4 m) can be deployed in a wide range of research topics if equipped with state-of-the-art instruments. In this talk, I will focus on the astronomical spectroscopy and spectroscopic surveys that could be considered as the main realm of operation of the mid-size telescopes in the forthcoming years. I will review the most novel spectroscopy techniques and methods, including massive-multiplex spectroscopy, Integral Field Units (IFUs), high resolution (R>20’000) stable spectrographs, and will introduce some of the existing facilities, developed/is developing for mid-size telescopes similar to INO340. I will briefly point to the desired science goals of the ongoing/future spectroscopic surveys that could be delivered by 2-4m-class optical telescopes. I hope this talk to be followed by a discussion panel to draw a realistic and flexible instrumentation plan for INO340 that could react to changes in the direction of science over the coming years.

 

 


Uncovering the thermal and non-thermal processes in the ISM using optical observations of hydrogen recombination lines

 

Fatemeh Tabatabaei

 

Studying the thermal and non-thermal processes in the ISM is vital to address the role of the ISM in the evolution of galaxies. This can be best studied by combining the emission observed in the optical and radio regimes in galaxies. The optical hydrogen recombination lines trace the thermal processes in the ionized gas. The radio continuum emission provides a dust-unbiased tracer of both the thermal and nonthermal processes through its free-free and synchrotron components. However, separating these two components has been a historically technical challenge in radio astronomy. I developed a separation technique for galaxies that is based on the hydrogen recombination lines emission to trace the free-free continuum emission at radio frequencies. The nonthermal emission is then obtained by subtracting the thermal emission from the observed radio continuum maps. To de-redden the optical line emission, different methods are used depending on the data available. The Balmer-line-ratio method can be ideally used to correct the optical lines for extinction. Although mapping these nebular lines in galaxies is of fundamental importance, unfortunately, not many successful efforts have been made mapping them in galaxies, except for the Halpha line, thanks to its brightness. I will discuss how the 3.4m can be at the forefront of the ISM studies in galaxies near and far with these observations.

 


3D structures of the local molecular clouds and their implications for star formation

 

Sara Rezaei Khoshbakht

 

The unprecedented astrometry from the Gaia mission has opened a new door to studying the solar neighborhood in great detail. In order to get the wealth of information in this data, we have developed a state-of-the-art, three-dimensional dust mapping technique using the Gaussian process, that provides detailed 3D maps of the Milky Way. We obtain the 3D positions of stars from Gaia, and their individual extinction using multi-band photometry, which is then used as the input for our model. Taking into account both distance and extinction uncertainties, together with the 3D spatial correlation between neighboring points, we produce 3D maps of the local molecular clouds, revealing the 3D structures of individual clouds in fine detail.

In this talk, I will start by introducing dust and why it is an important component of the interstellar medium. Then I will briefly explain our Gaussian-process-based technique and its application to mapping the star-forming regions in the Milky Way. I will finish by showing some of our latest results on the important role of the 3D shape in star formation properties of molecular clouds.

 

 


جستجوی نشانه هایی از مولکول های ارگانیک در ابرهای پخشی

 

Amin Farhang

 

 

 


Magnetic and flare activity of K-type dwarf binaries

 

Hadis Goudarzi

 

We analyze the light curve of 199 dwarf binary stars from the Kepler mission. All of them are K-type active stars in binary systems which their flare activity has been confirmed before. From the light-curve modulation, we can infer stability, relative coverage, and contrast of the magnetic structures. In addition, we extract flare components from the light-curve fluctuations and study the flare characteristics such as total time duration, power, and magnitude. These magnetic activity indicators show the same increase with Rossby number such as single stars and have the same saturation behavior in high rotation periods. Also, the activity level of binary stars is slightly higher than the single main-sequence stars but lower than the Sub-giant branch. So, we conclude that the production of the magnetic field through the dynamo procedure is more affected by the convective depth rather than the rotation period.

 

 


Galaxy formation in the L-Galaxies semi-analytical model and the IllustrisTNG hydrodynamical simulations

 

Mohammadreza Ayromlou

 

In this talk, I will present an updated version of the Munich semi-analytical model of galaxy formation, L-Galaxies. The correlation between galaxy evolution and environment has been known for years, with one of the well-known examples being the higher fraction of quenched satellite galaxies within the virial radius of galaxy clusters. Current studies in the literature are usually limited to satellite galaxies within the halo boundary, while satellite galaxies beyond the halo boundary and central galaxies are less investigated. In recent work, we updated the Munich model of galaxy formation, L-Galaxies, and employed several observations, including SDSS and HSC, to discover the correlations between galaxy properties (e.g. star formation rate) and their environment up to large scales. We introduce a local background environment (LBE) estimator to quantify the environment locally for all galaxies within cosmological simulations. We then use the time-evolving local environment of galaxies to develop a method to better account for environmental processes for all galaxies within the L-Galaxies model. We recalibrate the updated model using an MCMC method and a few observational constraints. By comparing our results to data on galaxy properties in different environments from different surveys (e.g. SDSS, HSC), we find strong environmental dependencies, both in the updated model and in the observations, up to several virial radii of massive dark matter haloes. This is likely to influence the correlations between galaxies up to tens of Megaparsecs.

 

 


تحول کهکشان ها در شبکه کیهانی

 

Bahram Mobasher

 

 

 


ابزارگان برای رصد سیارات فراخورشیدی

 

Sohrab Rahvar

 

 

 


gravitational microlensing and detecting habitable and free-floating exoplanets

 

Sedigheh Sajadian

 

ریزهمگرایی گرانشی، تقویت نور یک ستاره در اثر عبور از میدان گرانشی یک جسم سنگین، یک روش برای آشکارسازی سیارات فراخورشیدی می باشد. در این روش اغلب اثرات گرانشی سیارات فراخورشیدی که حول جسم زمینه ای (عدسی) می چرخند،  برروی مسیر حرکت نور باعث  ایجاد اختلالی کوچک در منحنی نوری ستاره های پس زمینه می شود.  یکی از انواع سیارات فراخورشیدی،  سیارات قابل سکونت است که در ناحیه زیست پذیر اطراف ستاره مادر قرار دارند.  کشف این دسته از سیارات زیست پذیر، گام مهمی در راستای کشف حیات فرازمینی است.  در این سمینار،  جنبه های مختلف کشف این نوع از سیارت فراخورشیدی به کمک ریزهمگرایی گرانشی را توضیح خواهیم  داد.  همچنین آشکارسازی آنها به کمک تلسکوپ فضایی  رومان بررسی خواهد شد.  در ادامه در مورد آشکارسازی سیارات فراخورشیدی سرگردان  در راستای ابر های ماژلانی به کمک ریزهمگرایی گرانشی و تلسکوپ رومان توضیح خواهم داد.

 

 


Measuring the stellar atmosphere parameters using follow-up polarimetry

microlensing observations

 

Elaheh Khalouei

 

 

 


Comprehensive analysis of TESS Full Orbital Phase Curve of WASP-121b

 

Mohammad Eftekhar

 

We present the full phase curve analysis of the ultrahot Jupiter WASP-121b ($R_p \simeq 1.865 R_J, M_p \simeq 1.184 M_J $) using observations from the Transiting Exoplanet Survey Satellite (TESS). Our comprehensive phase curve model includes primary transit, secondary eclipse, thermal emission, reflection, and ellipsoidal tidal distortion, which are jointly fit to extract the information of all parameters simultaneously from the data sets. We also evaluated and calculated the amplitude of Doppler beaming to be $\sim 2$ ppm, but given the precision of the photometric data, we found it to be insignificant. After removing the instrumental systematic noise, we reliably detect the secondary eclipse with a depth of $489_{-10}^{+16}$ parts-per-million (ppm), dominated by thermal emission. Using the TESS bandpass, we measure the dayside $2941_{-150}^{+61} K$ and nightside $2236_{-97}^{+38} K $ temperatures of WASP-121b. We find that a hotspot is well aligned with the substellar point, leading to the conclusion that there is an inefficient heat distribution from the dayside to the nightside. Our estimated geometric albedo, $A_g = 0.069_{-0.02}^{+0.06}$, suggest that WASP-121b has a low geometric albedo. Finally, our estimated amplitude of the ellipsoidal variation signal is in agreement with the predictions of the theoretical expectations.

 

 


HD207897 b: A dense sub-Neptune transiting a nearby and bright K-type star

 

Neda Heidari

 

We present the discovery and characterization of a transiting sub-Neptune orbiting with a 16.20-day period around a nearby (28 pc) and bright (V=8.37) K0V star HD207897 (TOI-1611). This discovery is based on photometric measurements from the Transiting Exoplanet Survey Satellite (TESS) mission and radial velocity (RV) observations from the SOPHIE, Automated Planet Finder (APF) and HIRES high precision spectrographs. We used EXOFASTv2 for simultaneously modeling the parameters of the planet and its host star, combining photometric and RV data to determine the planetary system parameters. We show that the planet has a radius of 2.50±0.08 RE and a mass of either 14.4±1.6 ME or 15.9±1.6 ME with nearly equal probability; the two solutions correspond to two possibilities for the stellar activity period. Hence, the density is either 5.1±0.7g cm−3 or 5.5 0.8−0.7g cm−3, making it one of the relatively rare dense sub-Neptunes. The existence of such a dense planet at only 0.12 AU from its host star is unusual in the currently observed sub-Neptune (2<RE<4) population. The most likely scenario is that this planet has migrated to its current position.

 


تابع جرم اولیه ستاره ای: از خوشه های ستاره ای تا کهکشانها

 

Hosein Haghi

 

 

 


Kinematical Asymmetry in the Dwarf Irregular Galaxy WLM and a Perturbed Halo Potential.

 

Maryam Khademi

 

WLM is a dwarf irregular that is seen almost edge-on that has prompted a number of kinematical studies investigating its rotation curve and its dark matter content.

In this paper, we investigate the origin of the strong asymmetry of the rotation curve, which shows a significant discrepancy between the approaching and the receding side. We first examine whether an $m = 1$ perturbation (lopsidedness) in the halo potential could be a mechanism creating such kinematical asymmetry. To do so, we fit a theoretical rotational velocity associated with an $m = 1$ perturbation in the halo potential model to the observed data via a $\chi-$squared minimization method. We show that a lopsided halo potential model can explain the asymmetry in the kinematic data reasonably well. We then verify that the kinematical classification of WLM shows that its velocity field is significantly perturbed due to both its asymmetrical rotation curve and also its peculiar velocity dispersion map. In addition, based on a kinemetry analysis, we find that it is possible for WLM to lie in the transition region, where the disk and merger coexist. In conclusion, it appears that the rotation curve of WLM diverges significantly from that of an ideal rotating disk, which may significantly affect investigations of its dark matter content.”

 

 


Tracing the role of AGB stars in the Galactic Fluorine budget    

 

Maryam Saberi

 

The cosmic origin of fluorine is still uncertain. AGB  stars are among the few candidates to synthesize F in our Galaxy, however, their contribution is not clear. In this talk, I will present first the detection of AlF line emission, one of the two main carriers of F in the gas-phase in the outflow of AGB stars, towards a sample of five oxygen-rich AGB stars with ALMA. I will present the results of the population diagram method of estimating the AlF column density and fractional abundance in our sample and compare it with the Solar F budget. I will show that the AlF fractional abundance which gives a lower limit to the total F budget in the gas phase in the CSE is consistent with the Solar F budget in all observed sources in our sample. Finally, I will discuss the ongoing work of observationally tracing the role of AGB stars in the total F budget in our galaxy.

 


Formation and Evolution of LG Dwarf Galaxies with Monitoring Survey of Long Period Variable Stars

 

Elham Saremi

Dwarf galaxies in the Local Group (LG) represent a distinct as well as a diverse family of tracers of the earliest phases of galaxy assembly and the processing resulting from galactic harassment. Their stellar populations can be resolved and used as probes of the evolution of their host galaxy. In this regard, we conducted an optical monitoring survey in nearby dwarf galaxies with the 2.5 m Isaac Newton Telescope. Fifty-five dwarf galaxies and four isolated globular clusters in the Local Group were observed with the Wide Field Camera. The main aims of this survey are to identify the most evolved asymptotic giant branch (AGB) stars and red supergiants at the end-point of their evolution based on their pulsational instability, use their distribution over luminosity to reconstruct the star formation history, quantify the dust production and mass loss from modeling the multiwavelength spectral energy distributions (SEDs), and relate this to luminosity and radius variations.

 


The star formation history of Andromeda VII derived from long-period variable stars

 

Mahdieh Navabi

 

We have examined the star formation history (SFH) of Andromeda VII (And VII), the brightest and most massive dwarf spheroidal (dSph) satellite of the Andromeda galaxy (M 31). Although M 31 is surrounded by several dSph companions with old stellar populations and low metallicity, it has a metal-rich stellar halo with an age of 6−8 Gyr. This indicates that any evolutionary association between the stellar halo of M 31 and its dSph system is frail. Therefore, the question is whether And VII (a high-metallicity dSph located ∼220 kpc from M 31), can be associated with M 31’s young, metal-rich halo. Here, we perform the first reconstruction of the SFH of And VII employing long-period variable (LPV) stars. As the most-evolved asymptotic giant branch (AGB) and red supergiant (RSG) stars, the birth mass of LPVs can be determined by connecting their near-infrared photometry to theoretical evolutionary tracks. We found 55 LPV candidates within two half-light radii, using multi-epoch imaging with the Isaac Newton Telescope in the i and V bands. Based on their birth mass function, the star-formation rate (SFR) of And VII was obtained as a function of cosmic time. The main epoch of star formation occurred ≃6.2 Gyr ago with a SFR of 0.006±0.002 M⊙ yr−1.

 

 


The low surface brightness universe

 

Mohammad Akhlaghi

 

Except for the solar system planets, resolved stars or cosmic rays, most objects in astronomical images don’t have a sharp edge! For example, comets in the solar system, galactic cirri or planetary nebula in the interstellar medium of the Milky Way, galaxy stellar halos, the intra-cluster medium, or the cosmic web filaments. Due to the vast physical size of these diffuse low surface brightness features, and the weak forces that affect at such large distances, it is very hard to define a “border” or “edge”! As we observe more (deeper data), they just become larger! But what makes them even more intriguing is that the physical processes underlying the dynamics (or shape), content, chemistry, and star formation history of such regions are, by their nature, weakly affected by the internal properties of the object itself, and helps put it in the larger context. For example, the previous minor merger orbits that are visible through the beautiful stellar streams of the local universe galaxies when digging below the 27th or 28th magnitude/arcsec^2 surface brightness limit. However, because of their low signal-to-noise ratio in individual exposures, such diffuse photons are mostly lost in the default reduction pipelines of most instruments/surveys (resulting in the loss of almost 1 mag/arcsec^2 sensitivity!). Our methods (NoiseChisel as part of GNU Astronomy Utilities or Gnuastro), have also been shown to solve many systematic biases for the central, high signal-to-noise ratio, regions. We have already implemented most of the core concepts presented here to the first scientific commissioning data from Mount Gargash (the Sherkarchi array; presented separately by Zahra Sharbaf). Besides, our methods are now also being tested for the future pipelines of the European Space Agency’s Euclid mission, as well as the Javalambre Physics of the Accelerating Universe (J-PAS) survey. J-PAS will be using a 2.5-meter telescope (like SDSS) to observe the northern sky (like SDSS), BUT in 54 filters (unlike SDSS; which only had 5 filters!). The J-PAS filters are spectrally-contiguous narrow-bands, providing blind photo-spectra of all objects over thousands of degrees squared. This opens up a whole new discovery dimension to the universe (spectral: recall that all bona fide spectrometers need pre-selection and cannot be blind). This includes exciting potentials in the low surface brightness regime.


Scientific commissioning of the Iranian national observatory lens array (Shekarchi): a stellar halo of M33

 

Zahra Sharbaf

 

There is a large, irregular, low surface brightness substructure around M33. Deep, wide-field observations at the distance of M33 will provide insight into its evolution (whether accretion events dominate these structures or are there tidal distortion between them). The PAndAS survey explored the stellar populations and this feature’s structure (M33 halo) but with resolved stars. The field of view of the Iranian National Observatory Lens Array (Shekarchi) is more than 2.5 of the M33 size, so it is possible to observe M33’s halo for many hours through the low surface brightness signal of those stars.